Handbook of Fruits andFruit ProcessingHandbook of Fruits andFruit ProcessingEditorY. H. HuiAssociate EditorsJ ozsef Barta, M. Pilar Cano, Todd W. Gusek,Jiwan S. Sidhu, and Nirmal K. SinhaC 2006 Blackwell PublishingAll rights reservedBlackwell Publishing Professional2121 State Avenue, Ames, Iowa 50014, USAOrders: 1-800-862-6657Ofce: 1-515-292-0140Fax: 1-515-292-3348Web site: www.blackwellprofessional.comBlackwell Publishing Ltd9600 Garsington Road, Oxford OX4 2DQ, UKTel.: +44 (0)1865 776868Blackwell Publishing Asia550 Swanston Street, Carlton, Victoria 3053, AustraliaTel.: +61 (0)3 8359 1011Authorization to photocopy items for internal or per-sonal use, or the internal or personal use of specicclients, is granted by Blackwell Publishing, providedthat the base fee of $.10 per copy is paid directly tothe Copyright Clearance Center, 222 Rosewood Drive,Danvers, MA 01923. For those organizations that havebeen granted a photocopy license by CCC, a sepa-rate system of payments has been arranged. The feecodes for users of the Transactional Reporting Serviceare ISBN-13: 978-0-8138-1981-5; ISBN-10: 0-8138-1981-4/2006 $.10.First edition, 2006Library of Congress Cataloging-in-Publication DataHandbook of fruits and fruit processing / editor, Y.H.Hui; associate editors, J ozsef Barta . . .[et al.]. 1st ed.p. cm.Includes index.ISBN-13: 978-0-8138-1981-5 (alk. paper)ISBN-10: 0-8138-1981-4 (alk. paper)1. Food industry and trade. 2. FruitProcessing.I. Hui, Y. H. (Yiu H.) II. Barta, J ozsef.TP370.H264 2006664

.8dc222005013055The last digit is the print number: 9 8 7 6 5 4 3 2 1ContentsContributors, viiPreface, xiPart I Processing Technology1. Fruit Microbiology, 3A. Kalia and R. P. Gupta2. Nutritional Values of Fruits, 29C. S anchez-Moreno, S. De Pascual-Teresa, B. De Ancos, and M. P. Cano3. Fruit Processing: Principles of Heat Treatment, 45I. K ormendy4. Fruit Freezing Principles, 59B. De Ancos, C. S anchez-Moreno, S. De Pascual-Teresa, and M. P. Cano5. Fruit Drying Principles, 81J. Barta6. Non-Thermal Pasteurization of Fruit Juice Using High Voltage Pulsed Electric Fields, 95Zs. Cserhalmi7. Minimally Processed Fruits and Fruit Products and Their Microbiological Safety, 115Cs. Balla and J. Farkas8. Fresh-Cut Fruits, 129O. Martn-Belloso, R. Soliva-Fortuny, and G. Oms-Oliu9. Food Additives in Fruit Processing, 145P. S. Raju and A. S. Bawa10. Fruit Processing Waste Management, 171J. Monspart-S enyiPart II Products Manufacturing11. Manufacturing Jams and Jellies, 189H. S. Vibhakara and A. S. Bawa12. Manufacturing Fruit Beverages, 205E. Horv ath-Kerkai13. Fruit as an Ingredient in a Fruit Product, 217Gy. P atkai14. Fruit Processing Plant, 231J. Barta15. Fruits: Sanitation and Safety, 245S. Al-Zenki and H. Al-Omariahvvi ContentsPart III Commodity Processing16. Apples, 265N. K. Sinha17. Apricots, 279M. Siddiq18. Horticultural and Quality Aspects of Citrus Fruits, 293M. J. Rodrigo and L. Zacaras19. Oranges and Citrus Juices, 309K. S. Sandhu and K. S. Minhas20. Sweet Cherries, 359J. Alonso and R. Alique21. Cranberry, Blueberry, Currant, and Gooseberry, 369K. K. Girard and N. K. Sinha22. Date Fruits Production and Processing, 391J. S. Sidhu23. Grape Juice, 421O. Martn-Belloso and A. R. Marsell es-Fontanet24. Grapes and Raisins, 439N. R. Bhat, B. B. Desai, and M. K. Suleiman25. Grape and Wine Biotechnology: Setting New Goals for the Design ofImproved Grapevines, Wine Yeast, and Malolactic Bacteria, 453I. S. Pretorius26. Olive Processing, 491B. Gandul-Rojas and M. I. Mnguez-Mosquera27. Peach and Nectarine, 519M. Siddiq28. Pear Drying, 533R. de Pinho Ferreira Guin e29. Plums and Prunes, 553M. Siddiq30. Processing of Red Pepper Fruits (Capsicum annuum L.) for Productionof Paprika and Paprika Oleoresin, 565A. P erez-G alvez, M. Jar en-Gal an, and M. I. Mnguez-Mosquera31. Strawberries and Raspberries, 581N. K. Sinha32. Tropical Fruits: Guava, Lychee, Papaya, 597J. S. Sidhu33. Banana, Mango, and Passion Fruit, 635L. G. Occe na-Po34. Nutritional and Medicinal Uses of Prickly Pear Cladodes and Fruits:Processing Technology Experiences and Constraints, 651M. Hamdi35. Speciality Fruits Unique to Hungary, 665M. St eger-M at eIndex, 679ContributorsRafael Alique (Chapter 20)Instituto del Fro (CSIC)C/Jos Antonio Novais n 1028040 Madrid, SpainPhone: +34915492300Jess Alonso (Chapter 20)Instituto del Fro (CSIC)C/Jos Antonio Novais n 1028040 Madrid, SpainPhone: +34915492300E-mail: jalonso@if.csic.esHusam Al-Omariah (Chapter 15)Biotechnology DepartmentKuwait Institute for Scientic ResearchP.O. Box 24885, 13109-Safat, KuwaitSameer Al-Zenki (Chapter 15)Biotechnology DepartmentKuwait Institute for Scientic ResearchP.O. Box 24885, 13109-Safat, KuwaitPhone: (965)-483-6100Fax: (965)-483-4670E-mail: szenki@kisr.edu.kwBegoa De Ancos (Chapters 2, 4)Department of Plant Foods Scienceand Technology, Instituto del FroConsejo Superior de InvestigacionesCientcas (CSIC) Ciudad UniversitariaE-28040 Madrid, SpainE-mail: ancos@if.csic.esCsaba Balla (Chapter 7)Corvinus University of Budapest, Faculty ofFood Science, Department of Refrigerationand Livestock Products TechnologyHungary 1118, Budapest, Mnesi t 45Phone: 36-1-482-6064Fax: 36-1-482-6321E-mail: csaba.balla@uni-corvinus.huJ ozsef Barta, Ph.D. (Chapters 5, 14)Head of the DepartmentCorvinus University of BudapestFaculty of Food ScienceDepartment of Food PreservationBudapest, Mnesi t 45Hungary 1118Phone: 36-1-482-6212Fax: 36-1-482-6327E-mail: jozsef.barta@uni-corvinus.huA.S. Bawa (Chapters 9, 11)Fruits and Vegetables TechnologyDefence Food Research LaboratorySiddarthanagar, Mysore-570 011, IndiaPhone: 0821-247-3783Fax: 0821-247-3468E-mail: dfoodlab@sancharnet.inN. R. Bhat (Chapter 24)Arid Land Agriculture DepartmentKuwait Institute for Scientic ResearchP.O. Box 24885, 13109-Safat, KuwaitE-mail: nbhat@safat.kisr.edu.kwviiviii ContributorsM. Pilar Cano, Ph.D. (Chapters 2, 4)DirectorInstituto del Fro-CSICC/Jose Antonio Novais, 10Ciudad Universitaria28040-Madrid, SpainPhone: 34-91-5492300Fax: 34-91-5493627E-mail: pcano@if.csic.esZsuzsanna Cserhalmi (Chapter 6)Central Food Research InstituteHungary 1022 Budapest, Hermann O. u. 15Phone: 36-1-214-1248Fax: 36-1-355-8928E-mail: zs.cserhalmi@cfri.huSonia De Pascual-Teresa (Chapters 2, 4)Department of Plant Foods Scienceand Technology, Instituto del FroConsejo Superior de InvestigacionesCientcas (CSIC) Ciudad UniversitariaE-28040 Madrid, SpainE-mail: soniapt@if.csic.esB. B. Desai (Chapter 24)Arid Land Agriculture DepartmentKuwait Institute for Scientic ResearchP.O. Box 24885, 13109-Safat, KuwaitJ ozsef Farkas (Chapter 7)Corvinus University of BudapestFaculty of Food Science, Departmentof Refrigeration and Livestock ProductsTechnology and Central Food Research InstituteHungary 1118, Budapest, Mnesi t 45and, 1022, Budapest, Hermann O. u. 15Phone: 36-1-482-6303Fax: 36-1-482-6321E-mail: j.farkas@cfri.huRaquel de Pinho Ferreira Guin e (Chapter 28)Associate ProfessorDepartment of Food EngineeringESAV, Polytechnic Institute of ViseuCampus Politcnico, Repeses3504-510 Viseu, PortugalE-mail: raquelguine@esav.ipv.ptBeatriz Gandul-Rojas (Chapter 26)Group of Chemistry and Biochemistryof Pigments. Food Biotechnology DepartmentInstituto de la Grasa (CSIC).Av. Padre Garca Tejero 4, 41012Sevilla, SpainKristen K. Girard (Chapter 21)Principal ScientistOcean Spray Cranberries, Inc.Ingredients1 Ocean Spray Dr.Middleboro MA 02349, USAE-mail: kgirard@oceanspray.comRajinder P. Gupta (Chapter 1)Department of Microbiology,College of Basic Sciences and HumanitiesPunjab Agricultural UniversityLudhiana-141004, Indiarpguptag@rediffmail.comTodd W. Gusek, Ph.D.Principal Scientist, Central ResearchCargill, Inc.PO Box 5699Minneapolis, MN 55440, USAPhone: (952)742-6523Fax: (952)742-4925E-mail: todd gusek@cargill.comM. Hamdi (Chapter 34)Director, Department of Biochemical and ChemicalEngineering Microbial and Food ProcessesHigher School of Food IndustriesNational Institute of Applied Sciencesand Technology. BP: 676. 1080 TunisiaPhone: 216-98-326675Fax: 216-71-704-329E-mail: moktar.hamdi@insat.rnu.tnEmoke Horvth-Kerkai (Chapter 12)Corvinus University of Budapest, Facultyof Food Science, Department ofFood Preservation Hungary 1118Budapest, Mnesi t 45.Phone: 36-1-482-6035Fax: 36-1-482-6327E-mail: emoke.kerkai@uni-corvinus.huContributors ixY. H. Hui, Ph.D.Senior ScientistScience Technology SystemP.O. Box 1374West Sacramento, CA 95691, USAPhone: 916-372-2655Fax: 916-372-2690E-mail: yhhui@aol.comManuel Jarn-Galn (Chapter 30)Group of Chemistry and Biochemistryof Pigments. Food Biotechnology DepartmentInstituto de la Grasa (CSIC)Av. Padre Garca Tejero 4, 41012Sevilla, SpainAnu Kalia (Chapter 1)Department of Microbiology,College of Basic Sciences and HumanitiesPunjab Agricultural UniversityLudhiana-141004, Indiakaliaanu@rediffmail.comImre Krmendy (Chapter 3)Corvinus University of Budapest,Faculty of Food Science, Departmentof Food Preservation Hungary 1118Budapest, Mnesi t 45Phone: 36-1-482-6212Fax: 36-1-482-6327E-mail: imre.kormendy@uni-corvinus.huOlga Martn-Belloso (Chapters 8, 23)Department of Food Technology, Universityof Lleida Av. Alcalde Rovira Roure, 191. 25198Lleida, SpainPhone: +34-973-702-593Fax: +34-973-702-596E-mail: omartin@tecal.udl.esAngel Robert Marsells-Fontanet (Chapter 23)Department of Food Technology, Universityof Lleida Av. Alcalde Rovira Roure, 191. 25198Lleida, SpainPhone: +34 973 702 593Fax: +34 973 702 596E-mail: rmarselles@tecal.udl.esM. Isabel Mnguez-Mosquera (Chapters 26, 30)Group of Chemistry and Biochemistryof Pigments. Food Biotechnology DepartmentInstituto de la Grasa (CSIC)Av. Padre Garca Tejero 4, 41012Sevilla, SpainPhone: +34954691054Fax: +34954691262E-mail: minguez@cica.es.Kuldip Singh Minhas (Chapter 19)ProfessorFood Science and TechnologyPunjab Agricultural UniversityLudhiana, Punjab, IndiaPhone: 0161-2401960 Extn. 305Judit Monspart-Snyi (Chapter 10)Corvinus University of Budapest, Facultyof Food Science, Department of Food PreservationHungary 1118, Budapest, Mnesi t 45Phone: 36-1-482-6037Fax: 36-1-482-6327E-mail: judit.senyi@uni-corvinus.huLillian G. Occea-Po (Chapter 33)Department of Food Science and Human NutritionMichigan State UniversityEast Lansing, MI 48824, USAPhone: 517-432-7022Fax: 517-353-8963E-mail: occena@msu.eduGemma Oms-Oliu (Chapter 8)Department of Food Technology, University ofLleida Av. Alcalde Rovira Roure, 191. 25198Lleida, SpainPhone: +34-973-702-593Fax: +34-973-702-596E-mail: goms@tecal.udl.esGyrgyi Ptkai (Chapter 13)Corvinus University of Budapest, Facultyof Food Science, Department of Food PreservationHungary 1118, Budapest, Mnesi t 45Phone: 36-1-482-6212Fax: 36-1-482-6327E-mail: gyorgyi.patkai@uni-corvinus.huAntonio Prez-Glvez (Chapter 30)Group of Chemistry and Biochemistryof Pigments, Food Biotechnology DepartmentInstituto de la Grasa (CSIC).Av. Padre Garca Tejero 4, 41012,Sevilla, Spainx ContributorsIsak S. Pretorius (Chapter 25)The Australian Wine Research InstitutePO Box 197, Glen OsmondAdelaide, SA 5064AustraliaPhone: +61-8-83036835Fax: +61-8-83036601E-mail: Sakkie.Pretorius@awri.com.auP.S. Raju (Chapter 9)Fruits and Vegetables TechnologyDefence Food Research LaboratorySiddarthanagar, Mysore-570 011, IndiaPhone: 0821-247-3783Fax: 0821-247-3468E-mail: dfoodlab@sancharnet.inMara Jess Rodrigo (Chapter 18)Instituto de Agroqumica y Tecnologade Alimentos (CSIC). Apartado Postal 7346100 Burjasot, Valencia, SpainConcepcin Snchez-Moreno (Chapters 2, 4)Department of Plant Foods Science andTechnology, Instituto del Fro, Consejo Superiorde Investigaciones Cientcas (CSIC)Ciudad Universitaria, E-28040 Madrid, SpainE-mail: csanchezm@if.csic.esKulwant S. Sandhu (Chapter 19)Sr. Veg. Technologist (KSS)Department of Food Science and TechnologyPunjab Agricultural UniversityLudhiana - 141 004, Punjab, IndiaPhone: 0161-2405257, 2401960 extn. 8478(KSS)E-mail: ptc@satyam.net.inJiwan S. Sidhu, Ph.D. (Chapters 22, 32)Professor, Department of Family ScienceCollege for Women, Kuwait UniversityP.O. Box 5969, Safat-13060, KuwaitPhone: (965)-254-0100 extn. 3307Fax: (965)-251-3929E-mails: jsidhu@cfw.kuniv.edu;jiwansidhu2001@yahoo.comMuhammad Siddiq (Chapters 17, 27, 29)Food Processing SpecialistDepartment of Food Science & Human NutritionMichigan State UniversityEast Lansing, MI 48824, USAPhone: 517-355-8474Fax: 517-353-8963E-mail: siddiq@msu.eduNirmal K. Sinha, Ph.D. (Chapters 16, 21, 31)VP, Research and DevelopmentGraceland Fruit, Inc.1123 Main StreetFrankfort, MI 49635, USAPhone: 231-352-7181Fax: 231-352-4711E-mail: nsinha@gracelandfruit.comRobert Soliva-Fortuny (Chapter 8)Department of Food Technology, Universityof Lleida Av. Alcalde Rovira Roure, 191. 25198Lleida, SpainPhone: +34-973-702-593Fax: +34-973-702-596E-mail: rsoliva@tecal.udl.esMnika Stger-Mt (Chapter 35)Corvinus University of Budapest, Facultyof Food Science, Department of Food PreservationHungary 1118, Budapest, Mnesi t 45Phone: 36-1-482-6034Fax: 36-1-482-6327E-mail: monika.stegernemate@uni-corvinus.huM. K. Suleiman (Chapter 24)Arid Land Agriculture DepartmentKuwait Institute for Scientic ResearchP.O. Box 24885, 13109-Safat, KuwaitH.S. Vibhakara (Chapter 11)Fruits and Vegetables TechnologyDefence Food Research LaboratorySiddarthanagar, Mysore-570 011, IndiaPhone: 0821-247-3949Fax: 0821-247-3468Lorenzo Zacaras (Chapter 18)Instituto de Agroqumica y Tecnologade Alimentos (CSIC). Apartado Postal 7346100 Burjasot, Valencia, SpainPhone: 34 963900022Fax: 34 963636301E-mail: lzacarias@iata.csic.es orcielor@iata.csic.esPrefaceIn the past 30 years, several professional referencebooks on fruits and fruit processing have been pub-lished. The senior editor of this volume was part ofan editorial teamthat published a two-volume text onthe subject in the mid-nineties.It may not be appropriate for us to state the ad-vantages of our book over the others available in themarket, especially in contents; however, each profes-sional reference treatise has its strengths. The deci-sion is left to the readers to determine which title bestsuits their requirement.This book presents the processing of fruits fromfour perspectives: scientic basis; manufacturing andengineering principles; production techniques; andprocessing of individual fruits.Part I presents up-to-date informationonthe funda-mental aspects and processing technology for fruitsand fruit products, covering:r Microbiologyr Nutritionr Heat treatmentr Freezingr Dryingr New technology: pulsed electric eldsr Minimal processingr Fresh-cut fruitsr Additivesr Waste managementPart II covers the manufacturing aspects of processedfruit products:r Jams and jelliesr Fruit beveragesr Fruit as an ingredientr A fruit processing plantr Sanitation and safety in a fruit processing plantPart III is from the commodity processing perspec-tive, covering important groups of fruits such as:r Applesr Apricotsr Citrus fruits and juicesr Sweet cherriesr Cranberries, blueberries, currants, andgooseberriesr Date fruitsr Grapes and raisins, including juices and winer Olivesr Peaches and nectarinesr Pearsr Plums and Prunesr Red pepper fruitsr Strawberries and raspberriesr Tropical fruits (guava, lychee, papaya, banana,mango, and passion fruit)Although many topical subjects are included in ourtext, we do not claimthat the coverage is comprehen-sive. This work is the result of the combined effortsof nearly fty professionals from industry, govern-ment, and academia. They represent eight countrieswith diverse expertise and backgrounds in the disci-pline of fruit science andtechnology. Aninternationaleditorial team of six members from four countriesled these experts. Each contributor or editor was re-sponsible for researching and reviewing subjects ofimmense depth, breadth, and complexity. Care andattention were paramount to ensure technical accu-racy for each topic. In sum, this volume is unique inmany respects. It is our sincere hope and belief that itwill serve as an essential reference on fruits and fruitprocessing for professionals in government, industry,and academia.xixii PrefaceWe wish to thank all the contributors for sharingtheir expertise throughout our journey. We also thankthe reviewers for giving their valuable comments onimproving the contents of each chapter. All these pro-fessionals are the ones who made this book possible.We trust that you will benet from the fruits of theirlabor.We know rsthand the challenges in developinga book of this scope. What follows are the difcul-ties in producing the book. We thank the editorialand production teams at Blackwell Publishing andTechBooks, Inc. for their time, effort, advice, andexpertise. You are the best judges of the quality ofthis work.Y. H. HuiJ. BartaM. P. CanoT. W. GusekJ. S. SidhuN. SinhaPart IProcessing TechnologyHandbook of Fruits and Fruit ProcessingEdited by Y. H. HuiCopyright 2006 by Blackwell Publishing1Fruit MicrobiologyAnu Kalia and Rajinder P. GuptaIntroductionNormal Microora of Fresh FruitsNormal Microora of Processed Fruit ProductsFactors Affecting Microbial GrowthIntrinsic FactorsExtrinsic FactorImplicit FactorsFactors Affecting Microbial Quality and Fruit SpoilagePreharvest FactorsPostharvest Handling and ProcessingFruit SpoilageTrue PathogensOpportunistic PathogensModes of Fruit SpoilageMethods to Evaluate Microbial QualityConventional TechniquesNew Methods for Rapid AnalysisMaintaining Microbial Quality of FruitsPostharvest and Storage ConsiderationsFruit SafetyAssociated Pathogens and Sources of ContaminationPreharvest Sources of ContaminationContamination During Postharvest ProcessingSafety and SanitationHealth ImplicationsFuture PerspectivesReferencesINTRODUCTIONMicrobiology is the science that deals with the studyof microscopic critters inhabiting planet earth, andof living organisms residing in earth. Microbe as ageneral termfeatures amalgamof a variety of diversemicroorganisms with the range spanning from elec-tronmicroscopical cyrstallizable viruses, nucleoidbearing unicellular prokaryotic bacteria to eukary-otic multicellular fungi and protists. The omnipresentfeature of microbes advocates their unquestionablepresence on external surface of plant and plant prod-ucts, particularly skin of fruits and vegetables.Fruits and vegetables are vital to our health andwell being, as they are furnished with essential vi-tamins, minerals, ber, and other health-promotingphytochemicals. The present health-conscious gen-eration prefers a diet exhibiting low calories andlow fat/sodium contents. A great importance of in-take of fruits everyday has been found to half therisk of developing cancer and may also reduce therisk of heart disease, diabetes, stroke, obesity, birthdefects, cataract, osteoporosis, and many more tocount. Over the past 20 years, the consumption offresh fruits and vegetables in industrialized coun-tries has increased. However, this has also hiked thechances of outbreaks of food poisoning and food in-fections related to consumption of fresh fruits anduncooked vegetable salads. Many workers have de-scribed the changes that may contribute to the in-crease in diseases associated with the consumption ofraw fruits and vegetables in industrialized countriesand foods in general (Hedberg et al., 1994; Altekruseand Swerdlow, 1996; Altekruse et al., 1997; Potteret al., 1997; Bean et al., 1997). A healthy fruit sur-face harbors diverse range of microbes, which maybe the normal microora, or the microbes inoculatedduring the processing of fresh produce (Hanklin andLacy, 1992; Nguyen and Carlin, 1994). However, themicroora could be plant pathogens, opportunisticpathogens, or non-plant pathogenic species. Accord-ing to Center for Disease Control and Prevention(CDCP), among the number of documented out-breaks of human infections associated with con-sumption of rawfruits, vegetables, and unpasteurizedfruit juices, more than 50% of outbreaks occur with3Handbook of Fruits and Fruit ProcessingEdited by Y. H. HuiCopyright 2006 by Blackwell Publishing4 Part I: Processing Technologyunidentied etiological agents. These new outbreaksof fresh-produce-related food poisoning include ma-jor outbreaks by tiny culprits as Escherichia coli0157:H7, Salmonella, Shigella, Cyclospora, Hepati-tis A virus, Norwalk disease virus, on a variety offruits as cantaloupes, apples, raspberries, and otherfruits. Erickson and Kornacki (2003) have even ad-vocated the appearance of Bacillus anthracis as apotential food contaminant. Factors include global-ization of the food supply, inadvertent introduction ofpathogens into new geographical areas (Frost et al.,1995; Kapperud et al., 1995), the development ofnew virulence factors by microorganisms, decreasesin immunity among certain segments of the popula-tion, and changes in eating habits.NORMAL MICROFLORAOF FRESH FRUITSFresh fruits have an external toughness, may be waterproof, wax-coated protective covering, or skin thatfunctions as a barrier for entry of most plantpathogenic microbes. The skin, however, harbors avariety of microbes and so the normal microora offruits is varied and includes both bacteria and fungi(Hanklin and Lacy, 1992). These microbes getassociated with fruits, since a variety of sources suchas the blowing air, composted soil, insects asDrosophila melanogaster or the fruit y inoculatethe skin/outer surface with a variety of Gram-negative bacteria (predominantly Pseudomonas,Erwinia, Lactobacillus). Likewise, hand-pickingthe fresh produce inoculates the fruit surfaceswith Staphylococcus. Contact with soil, especiallypartially processed compost or manure, adds di-verse human pathogenic microbes generally of thefecal-oral type including the Enterobacter, Shigella,Salmonella, E. coli 0157:H7, Bacillus cereus, aswell as certain viruses such as Hepatitis A Virus,Rotavirus, and Norwalk disease viruses that aretransmitted by consumption of raw fruits. Normalfungal microora of fruits includes molds suchas Rhizopus, Aspergillus, Penicillum, Eurotium,Wallemia, while the yeasts such as Saccharomyces,Zygosaccharomyces, Hanseniaspora, Candida,Debaryomyces, and Pichia sp. are predominant.These microbes are restrained to remain outside onfruit surfaces as long as the skins are healthy andintact. Any cuts or bruises that appear during thepostharvest processing operations allow their entryto the less protected internal soft tissue.NORMAL MICROFLORA OFPROCESSED FRUIT PRODUCTSPostharvest processing methods include diverserange of physical and chemical treatments to enhancethe shelf life of fresh produce. The minimally pro-cessed fresh-cut fruits remain in a raw fresh statewithout freezing or thermal processing, or additionof preservatives or food additives, and may be eatenraw or conveniently cooked and consumed. Theseminimally processed fruits are washed, diced, peeled,trimmed, and packed, which lead to the removal offruits natural cuticle, letting easy access by outertrue or opportunistic normal microora to the internaldisrupted tissues abrassed during processing. Gornyand Kader (1996) observed that pear slices cut with afreshly sharpened knife retained visual quality longerthan the fruits cut with a dull hand-slicer.Rinsing of fresh produce with contaminated wa-ter or reusing processed water adds E. coli 0157:H7,Enterobacter, Shigella, Salmonella sp., Vibrio chlo-reae, Cryptosporidiumparvum, Giardia lamblia, Cy-clospora caytanensis, Toxiplasma gondii, and othercausative agents of foodborne illnesses in humans,thus increasing the microbial load of the fresh pro-duce that undergo further processing including addi-tion of undesirable pathogens from the crop.Fruits processed as fruit concentrates, jellies, jams,preserves, and syrups have reduced water activ-ity (aw) achieved by sufcient sugar addition andheating at 6082C, that kills most of xerotolerantfungi as well as restrains the growth of bacteria.Thus, the normal microora of such diligently pro-cessed fruit products may include highly osmophilicyeasts and certain endospore-forming Clostridium,Bacillus sp. that withstand canning procedures. Sim-ilar ora may appear for processed and pasteurizedfruit juices andnectars that loose most vegetative bac-teria, yeasts, and molds while retaining heat-resistantascospores or sclerotia producing Paecilomyces sp.,Aspergillus sp., and Penicillum sp. (Splittstoesser,1991). Recently, Walls and Chuyate (2000) reportedthe occurrence of Alicyclobacillus acidoterrestris,an endospore-forming bacteria in pasteurized orangeand apple juices.FACTORS AFFECTINGMICROBIAL GROWTHFruits are composed of polysaccharides, sugars, or-ganic acids, vitamins, minerals which function as em-inent food reservoirs or substrates dictating the kind1 Fruit Microbiology 5of microorganisms that will ourish and perpetuatein the presence of specic microora and specicenvironmental prevailing conditions. Hence, one canpredict the development of microora on the basisof substrate characteristics. Fresh fruits exhibit thepresence of mixed populations, and growth rate ofeach microbial type depends upon an array of factorsthat govern/inuence the appearance of dominatingpopulation, which include the following.Intrinsic FactorsThese imply the parameters that are an inherent partof the plant tissues (Mossel and Ingram, 1955) andthus are characteristics of the growth substrates thatinclude the following.Hydrogen Ion Concentration (pH)Microbial cells lack the ability to adjust their inter-nal pH, hence are affected by change in pH, so couldgrow best at pH values around neutral. Bacteria ex-hibit a narrow pH range with pathogenic bacteria be-ing the most fastidious; however, yeasts and moldsare more acid-tolerant than bacteria. Fruits possessmore acidic pH (55 g/day) include citrus fruits and juices.Table 2.3 shows the range of concentrations(amount per 100 g of edible portion) of thiamin, ri-boavin, niacin, pyridoxine, and folate fromselectedfruits.MineralsAn adequate intake of minerals is essential for a highnutritional quality of the diet, and it also contributesto the prevention of chronic nutrition related dis-eases. However, even in Western societies, intake ofsome minerals such as calcium, iron, and zinc is oftenmarginal in particular population groups e.g., smallchildren or female adolescents, while the intake ofsodium or magnesium, reach or exceed the recom-mendations.Table 2.4 shows the mineral content (amount per100 g of edible portion) from certain fruits.IronIron (Fe) is an essential nutrient that carries oxy-gen and forms part of the oxygen-carrying proteins,hemoglobin in red blood cells and myoglobin inmuscle. It is also a necessary component of variousenzymes. Body iron is concentrated in the storageforms, ferritin and hemosiderin, in bone marrow,liver, and spleen. Body iron stores can usually beestimated from the amount of ferritin protein inserum. Transferrin protein in the blood transports anddelivers iron to cells (Lukaski, 2004).The body normally regulates iron absorption inorder to replace the obligatory iron losses of about11.5 mg/day. The RDAs for iron are 10 mg for menover 10years andfor womenover 50years, and15mgfor 11- 50-year-old females (ASNS, 2004).Non-heme iron is the source of iron in the dietfrom plant foods. The absorption of non-heme ironis strongly inuenced by dietary components, whichbind iron in the intestinal lumen. Non-heme ironabsorption is usually from 1% to 20%. The maininhibitory substances are phytic acid from cerealgrains and legumes such as soy, and polyphenol com-pounds from beverages such as tea and coffee. Themain enhancers of iron absorption are ascorbic acidfrom fruits and vegetables, and the partially digestedpeptides from muscle tissues (Frossard et al., 2000;Lukaski, 2004).36 Part I: Processing TechnologyTable 2.4. Mineral Content of Fruits (Value per 100 g of Edible Portion)Fruit Fe (mg) Ca (mg) P (mg) Mg (mg) K (mg) Na (mg) Zn (mg) Cu (mg) Se (g)Apple 0.12 6 11 5 107 1 0.04 0.027 0.0Apricot 0.39 13 23 10 259 1 0.20 0.078 0.1Avocado 0.55 12 52 29 485 7 0.64 0.190 0.4Banana 0.26 5 22 27 358 1 0.15 0.078 1.0Cherry 0.36 13 21 11 222 0 0.07 0.060 0.0Grape 0.36 10 20 7 191 2 0.07 0.127 0.1Guava 0.31 20 25 10 284 3 0.23 0.103 0.6Kiwi fruit 0.41 26 40 30 332 5 Orange 0.10 40 14 10 181 0 0.07 0.045 0.5Papaya 0.10 24 5 10 257 3 0.07 0.016 0.6Passion fruit 1.60 12 68 29 348 28 0.10 0.086 0.6Peach 0.25 6 20 9 190 0 0.17 0.068 0.11Pear 0.17 9 11 7 119 1 0.10 0.082 0.1Pineapple 0.28 13 8 12 115 1 0.10 0.099 0.1Plum 0.17 6 16 7 157 0 0.10 0.057 0.0Raspberry 0.69 25 29 22 151 1 0.42 0.090 0.2Strawberry 0.42 16 24 13 153 1 0.14 0.048 0.4Source: USDA (2004).CalciumCalcium (Ca) is the most common mineral in the hu-man body. Calcium is a nutrient in the news becauseadequate intakes are an important determinant ofbone health and reduced risk of fracture or osteo-porosis (Frossard et al., 2000).Approximately 99%of total body calciumis in theskeleton and teeth, and 1% is in the blood and softtissues. Calcium has the following major biologicalfunctions: (a) structural as stores in the skeleton,(b) electrophysiologicalcarries a charge during anaction potential across membranes, (c) intracellularregulator, and (d) as a cofactor for extracellular en-zymes and regulatory proteins (Frossard et al., 2000;ASNS, 2004).The dietary recommendations vary with age.An amount of 1300 mg/day for individuals aged918 years, 1000 mg/day for individuals aged 1950 years, and 1200 mg/day for individuals over theage of 51 years. The recommended upper level ofcalcium is 2500 mg/day (IM, 1997; ASNS, 2004).Calcium is present in variable amounts in all thefoods and water we consume, although vegetables areone of the main sources. Of course, dairy products areexcellent sources of calcium.PhosphorusPhosphorus (P) is an essential mineral that is foundin all cells within the body. The body of the humanadult contains about 400500 g. The greatest amountof body phosphorus can be found primarily in bone(85%) and muscle (14%). Phosphorus is primarilyfound as phosphate (PO42). The nucleic acidsdeoxyribonucleic acid (DNA) and ribonucleic acid(RNA)are polymers based on phosphate estermonomers. The high-energy phosphate bond of ATPis the major energy currency of living organisms. Cellmembranes are composed largely of phospholipids.The inorganic constituents of bone are primarily acalcium phosphate salt. The metabolism of all ma-jor metabolic substrates depends on the functioningof phosphorus as a cofactor in a variety of enzymesand as the principal reservoir for metabolic energy(ASNS, 2004).The RDAs for phosphorus (mg/day) are basedon life stage groups. Among others, for youth918 years, the RDA is 1250 mg, which indicatesthe higher need for phosphorus during the adoles-cent growth. Adults 19 years and older have a RDAof 700 mg (IM, 1997; ASNS, 2004).MagnesiumMagnesium (Mg) is the fourth most abundant cationin the body, with 60% in the bone and 40% dis-tributed equally between muscle and non-muscularsoft tissue. Only 1% of magnesium is extracellular.Magnesium has an important role in at least 300 fun-damental enzymatic reactions, including the transferof phosphate groups, the acylation of coenzyme A in2 Nutritional Values of Fruits 37the initiation of fatty acid oxidation, and the hydrol-ysis of phosphate and pyrophosphate. In addition,it has a key role in neurotransmission and immunefunction. Magnesium acts as a calcium antagonistand interacts with nutrients, such as potassium, vita-min B-6, and boron (Lukaski, 2004; ASNS, 2004).The RDA, from the US Food and Nutrition Board,vary according to age and sex. The RDAs for mag-nesium are 320 and 420 mg/day for women and men(adults over 30years), respectively(IM, 1997; ASNS,2004).PotassiumPotassium (K) in the form of K+ is the most essen-tial cation of the cells. Its high intracellular concen-tration is regulated by the cell membrane throughthe sodiumpotassium pump. Most of the total bodypotassium is found in muscle tissue (ASNS, 2004).The estimated minimum requirement for potas-sium for adolescents and adults is 2000 mg or50 mEq/day. The usual dietary intake for adults isabout 100 mEq/day. Most foods contain potassium.The best food sources are fruits, vegetables, andjuices (IM, 2004; ASNS, 2004).SodiumSodium (Na) is the predominant cation in extracel-lular uid and its concentration is under tight home-ostatic control. Excess dietary sodium is excreted inthe urine. Sodium acts in consort with potassium tomaintain proper body water distribution and bloodpressure. Sodium is also important in maintainingthe proper acidbase balance and in the transmissionof nerve impulses (ASNS, 2004).The RDAs for sodium ranges from 120 mg/dayfor infants to 500 mg/day for adults and childrenabove 10 years. Recommendations for the maxi-mum amount of sodium that can be incorporatedinto a healthy diet range from 2400 to 3000 mg/day.The current recommendation for the general healthypopulation to reduce sodium intake has been a mat-ter of debate in the scientic community (Kumanyikaand Cutler, 1997; IM, 2004; ASNS, 2004).ZincZinc (Zn) acts as a stabilizer of the structures ofmembranes and cellular components. Its biochemicalfunction is as an essential component of a large num-ber of zinc-dependent enzymes, particularly in thesynthesis and degradation of carbohydrates, lipids,proteins, and nucleic acids. Zinc also plays a ma-jor role in gene expression (Frossard et al., 2000;Lukaski, 2004).The RDAs for zinc are 8 and 11 mg/day for womenand men, respectively (ASNS, 2004).CopperCopper (Cu) is utilized by most cells as a componentof enzymes that are involved in energy production(cytochrome oxidase), and in the protection of cellsfrom free radical damage (superoxide dismutase).Copper is also involved with an enzyme that strength-ens connective tissue (lysyl oxidase) and in brainneurotransmitters (dopamine hydroxylase) (ASNS,2004).The estimated safe and adequate intake for copperis 1.53.0 mg/day (ASNS, 2004).SeleniumSelenium (Se) is an essential trace element thatfunctions as a component of enzymes involvedin antioxidant protection and thyroid hormonemetabolism (ASNS, 2004).The RDAs are 70 g/day for adult males, and55 g/day for adult females. Foods of low proteincontent, including most fruits and vegetables, pro-vide little selenium. Food selenium is absorbed withefciencies of 6080% (ASNS, 2004).BIOACTIVE COMPOUNDSCarotenoidsCarotenoids are lipid-soluble plant pigments com-mon in photosynthetic plants. The term carotenoidsummarizes a class of structurally related pigments,mainly found in plants. At present, more than 600different carotenoids have been identied, althoughonly about two dozens are regularly consumed byhumans. The most prominent member of this groupis -carotene. Most carotenoids are structurally ar-ranged as two substituted or unsubstituted iononerings separated by four isoprene units containing nineconjugated double bonds, such as - and -carotene,lutein, and zeaxanthin, and - and -cryptoxanthin(Goodwin and Merce, 1983; Van den Berg et al.,2000). These carotenoids, along with lycopene, anacylic biosynthetic precursor of -carotene, are mostcommonly consumed and are most prevalent in hu-man plasma (Castenmiller and West, 1998).38 Part I: Processing TechnologyIII234 5 20' 19'16 17 19101112 14 15' 13' 9' 7'1 718 16' 17'6 89 13 15 14' 12'11'10' 8'6'20 18' 5' 4'1'3'2'Figure 2.1. Structure and numbering of the carotenoid carbon skeleton. (Source: Shahidi et al., 1998.)All carotenoids can be derived from an acyclicC40H56 unit by hydrogenation, dehydrogenation,cyclization and/or oxidation reactions (Fig. 2.1). Allspecic names are based on the stem name carotene,which corresponds to the structure and numbering inFigure 2.1 (Shahidi et al., 1998).The systemof conjugated double bonds inuencestheir physical, biochemical, and chemical properties.Based on their composition, carotenoids are subdi-vided into two groups. Those contain only carbonand hydrogen atoms, which are collectively assignedas carotenes, e.g., -carotene, -carotene, and ly-copene. The majority of natural carotenoids containat least one oxygenfunction, suchas keto, hydroxy, orepoxy groups, and are referred to as xanthophylls oroxocarotenoids. In their natural sources, carotenoidsmainly occur in the all-trans conguration (Goodwinand Merce, 1983; Van den Berg et al., 2000).Carotenoid pigments are of physiological interestin human nutrition, since some of them are vita-minAprecursors, especially-carotene. -Carotene,and - and -cryptoxanthin possess provitamin Aactivity, but to a lesser extent than -carotene. Onthe basis of epidemiological studies, diet rich in fruitsand vegetables containing carotenoids is suggested toprotect against degenerative diseases such as cancer,cardiovascular diseases, and macular degeneration.Recent clinical trials on supplemental -carotenehave reported a lack of protection against degener-ative diseases. Much of the evidence has supportedthe hypothesis that lipid oxidation or oxidative stressis the underlying mechanism in such diseases. Todate carotenoids are known to act as antioxidantsin vitro. In addition to quenching of singlet oxygen,carotenoids may react with radical species either byaddition reactions or through electron transfer reac-tions, which results in the formation of the carotenoidradical cation (Caneld et al., 1992; Sies and Krinsky,1995; Van den Berg et al., 2000; S anchez-Moreno etal., 2003c).Carotenoid intake assessment has been shown tobe complicated mainly because of the inconsisten-cies in food composition tables and databases. Thus,there is a need for more information about indi-vidual carotenoids. The estimated dietary intake ofcarotenoids in Western countries is in the range of9.516.1 mg/day. To ensure the intake of a sufcientquantity of antioxidants, the human diet, which real-istically contains 100500 g/day of fruit and vegeta-bles, should contain a high proportion of carotenoid-rich products. No formal diet recommendation forcarotenoids has yet been established, but some ex-perts suggest intake of 56 mg/day, which is abouttwice the average daily U.S. intake. In the case of vi-tamin A, for adult human males, the RDAis 1000 gretinyl Eq/day, and for adult females, 800 g retinylEq/day (ONeill et al., 2001; Trumbo et al., 2003).Citrus fruits are the major source of -cryptoxanthin in the Western diet. The major fruitcontributors to the carotenoid intake in Western dietsare orange (-cryptoxanthin and zeaxanthin), tanger-ine (-cryptoxanthin), peach (-cryptoxanthin andzeaxanthin), watermelon (lycopene), and banana (-carotene). Other relatively minor contributors arekiwi fruit, lemon, apple, pear, apricot, cherry, melon,strawberry, and grape (Granado et al., 1996; ONeillet al., 2001).FlavonoidsFlavonoids are the most common and widely dis-tributed group of plant phenolics. Over 5000 differentavonoids have been described to date and they areclassied into at least 10 chemical groups. Among2 Nutritional Values of Fruits 39A CBHOHOOHOHOOR1OHR1OHOHHOOHOHOHHOOH OR1R2HOOHOHOHR1R1 OR2HOOHFlavonesFlavanonesAnthocyanidinsIsoflavonesFlavonolsFlavanolsR1Apigenin HLuteolin OHR1 R2Kaempferol H HQuercetin OH HMyricetin OH OHR1 R2Catechin H OHEpicatechin OH HR1 R2Naringenin H OHHesperetin OH OCH3R1 R2Cyanidin OH HPelargonidin H HMalvidin OCH3 OCH3R1Daidzein HGenistein OHR1R2R2OOOOOOFigure 2.2. Structures of the mainavonoids in fruits. (Source:Harborne, 1993.)them, avones, avonols, avanols, avanones, an-thocyanins, and isoavones are particularly commonin fruits (Fig. 2.2). The most-studied members ofthese groups are included in Table 2.5, along withsome of their fruit sources (Bravo, 1998).Numerous epidemiological studies support theconcept that regular consumption of foods and bever-ages rich in antioxidant avonoids is associated witha decreased risk of cardiovascular disease mortality.There is also scientic evidence that avonoids may40 Part I: Processing TechnologyTable 2.5. Classication of Flavonoids and Their Presence in FruitsSubclasses Flavonoids FruitsFlavones Apigenin, luteolin Apples, blueberries, grapefruit,grapes, orangesFlavonols Quercetin, kaempferol, myricetin Apples, berries, plumsFlavanols Catechin, epicatechin,epigallocatechin gallateApples, berries, grapes, plumsFlavanones Hesperetin, naringenin Citrus fruitsAnthocyanins Cyanidin, pelargonidin, malvidin Berries, grapesIsoavones Genistein, daidzein Currants, passion fruitSource: De Pascual-Teresa et al. (2000) and Franke et al. (2004).protect against some cancers. It has been shown in thepast that avonoid content and structure may changewith technological processes increasing or decreas-ing their contents and biological activity (Garca-Alonso et al., 2004).Most of the existingavonoids infruits have shownantioxidant activity in in vitro studies, and almost allthe fruits that have been screened for their antioxidantactivity have shown to a lower or higher extent someantioxidant and radical scavenger activity.Other biological activities of avonoids seem tobe independent of their antioxidant activity. This isthe case of the oestrogen-like activity showed byisoavones. Isoavones have also shown an effecton total and HDL cholesterol levels in blood.Anthocyanins have shown to be effective in de-creasing capillary permeability and fragility and alsohave anti-inammatory and anti-oedema activities.Flavonols inhibit COX-2 activity and thus mayplay a role in the prevention of inammatory diseasesand cancer (De Pascual-Teresa et al., 2004).Factors like modication on the avonoid struc-ture or substitution by different sugars or acids maydeeply affect the biological activity of avonoids andinthis sense different processingof the fruits mayalsoinuence their benecial properties for humanhealth.PhytosterolsPlant-based foods contain a large number of plantsterols, also called phytosterols, as minor lipid com-ponents. Plant sterols have been reported to includeover 250different sterols andrelatedcompounds. Themost common sterols in fruits are -sitosterol, and its22-dehydro analogue stigmasterol, campesterol andavenasterol (4-desmethylsterols). Chemical struc-tures of these sterols are similar to cholesterol dif-fering in the side chain (Fig. 2.3). -Sitosterol andstigmasterol have ethyl groups at C-24, and campes-terol has a methyl group at the same position. Plantsterols can exist as free plant sterols, and as boundconjugates: esteried plant sterols (C-16 and C-1821HOA BC D4 6721 191118 20 23 252712161522 2426R2224Rsitosterol campesterolstigmasterol 5-cholestan-3-l 5-avenasterol24R24RFigure 2.3. Structures of cholesterol (5-cholestan-3-ol), sitosterol, campesterol, stigmasterol, and

5-avenasterol. (Source: Piironen et al., 2003.)2 Nutritional Values of Fruits 41fatty acid esters, and phenolic esters), plant sterylglycosides (-D-glucose), and acylated plant sterylglycosides (esteried at the 6-hydroxy group of thesugar moiety). All of these forms are integrated intoplant cell membranes (Piironen et al., 2000, 2003).Plant sterols are not endogenously synthesized inhumans, therefore, are derived from the diet enteringthe body only via intestinal absorption. Since plantsterols competitively inhibit cholesterol intestinal up-take, a major metabolic effect of dietary plant sterolsis the inhibition of absorption and subsequent com-pensatory stimulation of the synthesis of cholesterol.The ultimate effect is the lowering of serum choles-terol owingtothe enhancedeliminationof cholesterolin stools. Consequently, the higher the dietary intakeof plant sterols from the diet, the lower is the choles-terol absorptionandthe lower is the serumcholesterollevel (Ling and Jones, 1995; De Jong et al., 2003;Trautwein et al., 2003).The usual human diet contains currently around145405 mg/day of plant sterols. Dietary intake val-ues depend on type of food intake. Intakes, especiallythat of -sitosterol, are increased two- to threefold invegetarians. For healthy humans, the absorption rateof plant sterols is usually less than 5% of dietarylevels. Serum sterol levels of around 350270 g/dlin non-vegetarians have been observed (Ling andJones, 1995; Piironen et al., 2000).Vegetables and fruits are generally not regardedto be as good a source of sterols as cereals orvegetable oils. The plant sterol content in a foodmay vary depending on many factors, such as geneticbackground, growing conditions, tissue maturity, andpostharvest changes (Piironen et al., 2000). There arescarce data available on the content of plant sterols inthe edible portion of fruits (Wiehrauch and Gardner,1978; Morton et al., 1995). Recently, the fruits morecommonly consumed in Finland have been analyzed.Total sterols ranged from 6 mg/100 g (red currant)to 22 mg/100 g (lingonberry) of fresh weight, in allfruits, except avocado, which contained signicantlymore sterols, 75 mg/100 g. The content on dry weightbasis was above 100 mg/100 g in most products. Peelsand seeds were shown to contain more sterols thanedible parts (Piironen et al., 2003). In Sweden, therange of plant sterol for 14 fruits is 1.344 mg/100g (fresh weight), only passion fruit contains morethan 30 mg/100 g (Normen et al., 1999). Among thefruits found in both reports, orange shows the high-est plant sterol content, and banana the lowest. In allthe items analyzed, -sitosterol occurred at the high-est concentrations, followed by campesterol or stig-masterol. Detectable amounts of ve-saturated plantstanols, sitostanol, and campestanol, were found inspecic fruits such as pineapple.REFERENCESAnsorena-Artieda D. 2000. Frutas y Frutos Secos. In:Astiasar an I, Martinez A (Eds), Alimentos,Composici on y Propiedades. McGraw-HillInternational, New York, pp. 191211.ASNS (American Society for Nutritional Sciences).2004. http://www.nutrition.org (accessed 2004).Belitz HD, Grosch W (Eds). 1997. Qumica de losalimentos. Acribia S.A., Zaragoza.Bramley M, Elmadfa I, Kafatos A, Kelly FJ, Manios Y,Roxborough HE, Schuch W, Sheehy PJA, WagnerKH. 2000. Vitamin E. Journal of the Science ofFood and Agriculture 80:913938.Bravo L. 1998. Polyphenols: chemistry, dietarysources, metabolism, and nutritional signicance.Nutrition Reviews 56:317333.Brigelius-Floh e R, Kelly FJ, Salonen JT, Neuzil J,Zingg JM, Azzi A. 2002. The European perspectiveon vitamin E: current knowledge and futureresearch. The American Journal of ClinicalNutrition 76:703716.Caneld IM, Forage JW, Valenzuela JG. 1992.Carotenoids as cellular antioxidants. Proceeding ofthe Society of Experimental Biology and Medicine200:260265.Castenmiller JJM, West CE. 1998. Bioavailability andbioconversion of carotenoids. Annual Review ofNutrition 18:1938.Davey MW, Montagu MV, Inze D, Sanmartin M,Kanellis A, Smirnoff N, Benzie IJJ, Strain JJ, FavellD, Fletcher J. 2000. Plant L-ascorbic acid:chemistry, function, metabolism, bioavailability andeffects of processing. Journal of the Science of Foodand Agriculture 80:825860.De Jong A, Plat J, Mensink RP. 2003. Metaboliceffects of plant sterols and stanols. The Journal ofNutritional Biochemistry 14:362369.De Pascual-Teresa S, Johnston KL, DuPont MS,OLeary KA, Needs PW, Morgan LM, Clifford MN,Bao YP, Williamson G. 2004. Quercetin metabolitesregulate cyclooxygenase-2 transcription in humanlymphocytes ex vivo but not in vivo. The Journal ofNutrition 134:552557.De Pascual-Teresa S, Santos-Buelga C, Rivas-GonzaloJC. 2000. Quantitative analysis of avan-3-ols inSpanish foodstuffs and beverages. Journal ofAgricultural and Food Chemistry 48:53315337.Franke AA, Custer LJ, Arakaki C, Murphy SP. 2004.Vitamin C and avonoid levels of fruits andvegetables consumed in Hawaii. Journal of FoodComposition and Analysis 17:135.42 Part I: Processing TechnologyFrossard E, Bucher M, Machler F, Mozafar A, HurrellR. 2000. Potential for increasing the content andbioavailability of Fe, Zn and Ca in plants for humannutrition. Journal of the Science of Food andAgriculture 80:861879.Garcia-Alonso M, De Pascual-Teresa S, Santos-BuelgaC, Rivas-Gonzalo JC. 2004. Evaluation of theantioxidant properties of fruits. Food Chemistry84:1318.Goodwin TW, Merce EI. 1983. Introduction to PlantBiochemistry. Pergamon Press Ltd., London.Granado F, Olmedilla B, Blanco I, Rojas-Hidalgo E.1996. Major fruit and vegetables contributors to themain serum carotenoids in Spanish diet. EuropeanJournal of Clinical Nutrition 50:246250.Harborne JB. 1993. The Flavonoids. Advance inResearch Since 1986. Chapman & Hall,London.IM (Institute of Medicine). 1997. Committee on theScientic Evaluation of Dietary Reference Intakes.In: Dietary Reference Intakes for Calcium,Phosphorus, Magnesium, Vitamin D, and Fluoride.National Academy Press, Washington, DC.IM (Institute of Medicine). 1998. Committee on theScientic Evaluation of Dietary Reference Intakes.In: Dietary Reference Intakes for Thiamin,Riboavin, Niacin, Vitamin B6, Folate, VitaminB12, Pantothenic Acid, Biotin, and Choline.National Academy Press, Washington, DC.IM (Institute of Medicine). 2002. Food and NutritionBoard. In: Dietary Reference Intakes for Energy,Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol,Protein, and Amino Acids (Macronutrients).National Academy Press, Washington, DC.IM (Institute of Medicine). 2004. Food and NutritionBoard. In: Dietary Reference Intakes for Water,Potassium, Sodium, Chloride, and Sulfate. NationalAcademy Press, Washington, DC.Kumanyika SK, Cutler JA. 1997. Dietary sodiumreduction. Is there cause for concern? Journal of theAmerican College of Nutrition 16:192203.Li BW, Andrews KW, Pehrsson PR. 2002. Individualsugars, soluble, and insoluble dietary bre contentsof 70 high consumption foods. Journal of FoodComposition and Analysis 15:715723.Ling WH, Jones PJH. 1995. Dietary phytosterols: areview of metabolism, benets, and side effects.Life Sciences 57:195206.Lotito SB, Frei B. 2004. The increase in human plasmaantioxidant capacity after apple consumption is dueto the metabolic effect of fructose on urate, notapple-derived antioxidant avonoids. Free RadicalBiology and Medicine 37:251258.Lukaski HC. 2004. Vitamin and mineral status:effects on physical performance. Nutrition 20:632644.Moreiras O, Carbajal A, Cabrera L, Cuadrado C. 2001.Tablas de Composici on de los alimentos. EdicionesPir amide (Grupo Anaya), Madrid.Morton GM, Lee SM, Buss DH, Lawrence P. 1995.Intakes and major dietary sources of cholesterol andphytosterols in the British diet. Journal of HumanNutrition and Dietetics 8:429440.Normen L, Johnsson M, Andersson H, Van GamerenY, Dutta P. 1999. Plant sterols in vegetables andfruits commonly consumed in Sweden. EuropeanJournal of Clinical Nutrition 38:8489.ONeill ME, Carroll Y, Corridan B, Olmedilla B,Granado F, Blanco I, Berg H, Van-den Hininger I,Rousell AM, Chopra M, Southon S, Thurnham DI.2001. A European carotenoid database to assesscarotenoid intakes and its use in a ve-countrycomparative study. British Journal of Nutrition85:499507.Piironen V, Lindsay DG, Miettinen TA, Toivo J, LampiA-M. 2000. Plant sterols: biosynthesis, biologicalfunction and their importance to human nutrition.Journal of the Science of Food and Agriculture80:939966.Piironen V, Toivo J, Puupponen-Pimia R, Lampi A-M.2003. Plant sterols in vegetables, fruits and berries.Journal of the Science of Food and Agriculture83:330337.S anchez-Moreno C, Cano MP, De Ancos B, Plaza L,Olmedilla B, Granado F, Martn A. 2003a.High-pressurized orange juice consumption affectsplasma vitamin C, antioxidative status andinammatory markers in healthy humans. TheJournal of Nutrition 133:22042209.S anchez-Moreno C, Cano MP, De Ancos B, Plaza L,Olmedilla B, Granado F, Martn A. 2003b. Effect oforange juice intake on vitamin C concentrations andbiomarkers of antioxidant status in humans. TheAmerican Journal of Clinical Nutrition 78:454460.S anchez-Moreno C, Plaza L, De Ancos B, Cano MP.2003c. Quantitative bioactive compoundsassessment and their relative contribution to theantioxidant capacity of commercial orange juices.Journal of the Science of Food and Agriculture83:430439.Sardesai VM. 1998. Introduction to Clinical Nutrition.Marcel Dekker Inc., New York.Saura-Calixto F. 1987. Dietary bre complex in asample rich in condensed tannins and uronic acid.Food Chemistry 23:95106.Shahidi F, Metusalach, Brown JA. 1998. Carotenoidpigment in seafoods and aquaculture. CriticalReviews in Food Science and Nutrition 38:169.2 Nutritional Values of Fruits 43Sies H, Krinsky NI. 1995. Antioxidant vitamins and-carotene in disease prevention. The AmericanJournal of Clinical Nutrition 62S:1299S1540S.Simon JA, Hudes ES, Tice JA. 2001. Relation ofserum ascorbic acid to mortality among US adults.Journal of the American College of Nutrition20:255263.Taylor JS, Hamp JS, Johnston CS. 2000. Low intakesof vegetables and fruits, especially citrus fruits, leadto inadequate vitamin C intakes among adults.European Journal of Clinical Nutrition 54:573578.Torija-Isasa ME, C amara-Hurtado MM. 1999.Hortalizas, verduras y frutas. In:Hern andez-Rodriguez M, Sastre-Gallego A (Eds),Tratado de Nutrici on. Daz de Santos, Madrid,pp. 413423.Trautwein EA, Guus SM, Duchateau JE, Lin Y,Melnikov SM, Molhuizen HOF, Ntanios FY. 2003.Proposed mechanisms of cholesterol-loweringaction of plant sterols. European Journal of LipidScience and Technology 105:171185.Trumbo PR, Yates AA, Schlicker-Renfro S, Suitor C.2003. Dietary reference intakes: revised nutritionalequivalents for folate, vitamin E and provitamin Acarotenoids. Journal of Food Composition andAnalysis 16:379382.USDA. 2004. National Nutrient Database for StandardReference, Release 16-1.Van den Berg H, Faulks R, Granado F, Hirschberg J,Olmedilla B, Sandmann G, Southon S, Stahl W.2000. The potential for the improvement ofcarotenoid levels in foods and the likely systemiceffects. Journal of the Science of Food andAgriculture 80:880912.Villarino-Rodrguez A, Garca-Fern andez MC,Garcia-Arias MT. 2003. In: Garca-Arias MT,Garca-Fern andez MC (Eds), Frutas y Hortalizas enNutrici on y Diet etica. Universidad de Le on.Secretariado de publicaciones y mediosaudiovisuales, Le on, pp. 353366.Wiehrauch JL, Gardner JM. 1978. Sterols content offood of plant origin. Journal of the AmericanDietetic Association 73:3947.3Fruit Processing: Principlesof Heat TreatmentImre K ormendyReviewof Heat Treatment Processes andBasic Ideas of SafetySurvey of Industrial ProcessesBackground of Microbial SafetyHeat Treatment EquipmentClassicationBatch-Type Pasteurizers and Sterilizers for Food inContainer TreatmentContinuous Pasteurizers and Sterilizers for Food inContainer TreatmentStatements for Both Batch-Type and ContinuousApparatusFlow-Through Type Pasteurizers and SterilizersHeat Propagation Under Heat Treatment ConditionsHeat Conduction in Food Holding ContainersNatural and Forced Convection Heating of Food HoldingContainersHeat Transfer in Flow-Through Type Heat TreatmentUnitsLoad and Deformation of Containers Under Heat TreatmentConditionsContainers and Their Characteristic DamagesDeformation Versus Load CalculationsQuality Attribute ChangesAttribute KineticsAttribute Intensity Versus Time-dependent Temperaturein Food Holding ContainersCalculation Methods for Flow-Through Type ApparatusList of symbolsReferencesREVIEW OF HEAT TREATMENTPROCESSES AND BASIC IDEASOF SAFETYSurvey of Industrial ProcessesThe greatest quantity of processed fruit is preservedby heat treatment. A wide range of practical andtheoretical knowledge is needed for an industrialprocess, as Figure 3.1 illustrates. Food processinginvolves the elds of microbiology, plant biology,thermophysics, food rheology and chemistry, pack-aging technique, unit operations, reactor techniques,construction and materials science, machinery, andelectrophysics.The most important factors (besides the nature ofthe rawmaterial and type of product) for constructinga plant are as follows:r type and size of the container (e.g., from smallcans up to large tanks), andr mode of heat treatment (e.g., batch or continuouspasteurization of closed containers; full asepticprocess or some combination; temperatureand pressure above or below 100C and absolutepressure of 100 kPa).Background of Microbial SafetyEarly perceptions (Ball and Olson, 1957) initiatedthe use of rst-order (exponential) inactivation ki-netics for microbes, including constants as D, Dr,Tr, z and calculation of the heat treatment equiv-alent (F-value). These early ideas continue to befollowed. Meanwhile, concepts have been renedwith the availability of computer programs designedto calculate risk analysis for food safety in indus-trial food processing.The two safety aspects are health protection andcontrol of spoilage. The critical (cold) point or zone isthe location in the food, where the maximumconcen-tration of surviving microorganisms is expected. Cal-culating and measuring the concentration of surviv-ing microorganisms in the cold zone is an important45Handbook of Fruits and Fruit ProcessingEdited by Y. H. HuiCopyright 2006 by Blackwell Publishing46 Part I: Processing TechnologyReceptacleApparatusTransport processesin food materials Quality attributechangesContainersCansGlass jarsPouchesBoxesHeat treatment of filledand closed containersBatch processHeat conductionNatural convectionInactivation andmultiplication ofmicrobesChanges of chem.TanksContinuous process Forced convectionFluid mechanicsconcentrations andenzyme activitiesPortableFixedFlow-through type(aseptic and(Newtonian andnon-Newtonian)Sensory and physicalattributesquasi-aseptic processes)Kinetics theoryLoad and deformation Design of Ohmic and dielectricReactor technicsof receptacles heat exchangers heating Extreme values andaverages. H. treatmentequivalentsFigure 3.1. Co-operation between science and technology for achievements in heat treatment processes.part of health protection and food safety. Table 3.1summarizes the cold zones in the food processingindustry. Only surviving pathogens are involved inthe cold point calculations.Control of spoilage means that the number of non-pathogenic survivors which can multiply in the steril-ized food is limited by the process parameters, so thatthe ratio of spoiled cans (s) is very low. For example,if one in 10,000 cans (s = 104) is spoiled, and onecan initially contains N0V = 103harmful microbes(V is the can volume, N0 is the initial concentrationof microbes), then a pasteurization process is neededwhich reduces 103/104= 107microbes to one sur-vivor. Assuming rst-order kinetics [see Eq. 3.5] anddecimal reductiontime D=0.7minat 70Creferencetemperature, the necessary pasteurization equivalent(see later) isP = (log 107) 0.7 = 7 0.7 = 4.9 min.The cold zone is (in most cases) near the center ofa can, but it can shift toward the surface when llingand closing of hot food, because the surface zonecools down rst.Liquid food leaving a ow-through type sterilizeris a mixture of elements (including microbes) havingdifferent residence time periods. No distinction canbe made between maximum and average concentra-tions of surviving pathogens in this case. However,when food pieces are dispersed in a liquid, the max-imum survivor concentration will be expected in thecenter of the greatest piece withthe shortest residencetime.Most fruit products belong to the groups ofmedium- and high-acid foods (pH < 4). Typicalpathogenic bacteria are the Salmonella and Staphy-lococcus species, while lactic acid producing bacte-ria (Lactobacillus, Leuconostoc), though inhibitinggrowth of pathogens, can cause spoilage. Yeasts and3 Fruit Processing 47Table 3.1. Location of the Critical Zone or Critical Sample When Inactivating MicrobesProcess Characteristics Location of the Critical Zone or SampleFood in container: Central zone in the containerHeat conductionNatural convectionForced convectionNatural or forced convection + food pieces Central zone in the container + the core of food pieceFlow-through type, full aseptic:Liquid food or pureeCalculation of the average of survivors concentrationat the exitLiquid food or puree + food pieces Calculation of survivors concentration in the core ofthe largest piece with shortest residence timeFlow-through type heating + hot lledcontainers (quasi-aseptic):Surface zone in the container (after cooling)Liquid food or pureeLiquid food or puree + food pieces Surface zone of liquid food or in the largest piece withshortest residence time at the container wallmolds can also be harmful. The heat-resistant moldByssochlamys fulva cannot be destroyed by tempera-tures under 100C (Stumbo, 1973; Ramaswamy andAbbatemarco, 1996).Contrary to sterilization (pH > 4.5, T > 100C),no generally accepted reference temperature ex-ists for pasteurization, nor agreement on which or-ganisms are dangerous. Even the criteria for safeshelf-life (time, temperature, etc.) may be uncertain.However, pathogenic species must not survive andN/N0 = 108reduction of either pathogenic or otherspecies causing spoilage would do.HEAT TREATMENT EQUIPMENTClassificationThe major factors to consider are:1. Whether the food is pasteurized after llingindividual containers or in bulk before lling (fullaseptic and quasi-aseptic processes).2. Type, size, and material of the container or tank.3. Highest retort temperature under or above 100Cand pressure equal to or above atmosphericpressure.4. Operational character, batch or continuousoperation.5. Physical background of heating and cooling,considering both the equipment and food material.A great variety of applications can be found. Be-sides steam, hot-, and cold-water applications,new methods include combustion heating of cansor ohmic heating in aseptic processes. Steaminjection and infusion into viscous purees andevaporation cooling have also been adopted (aswell as microwave applications).Batch-Type Pasteurizers andSterilizers for Food in ContainerTreatmentOpen pasteurization tanks, lled with water, areheated by steam injection and cooled by cold wa-ter. Racks holding containers are lifted in and outfrom above by a traveling overhead crane. Heatingand cooling in the same tank in one cycle is un-economical. However, steam and water consumptioncan be decreased by modications (e.g., hot waterreservoirs).Horizontal retorts are favored by plants where dif-ferent products are processed in small or mediumvolumes. A wide variety of construction is available,usually with the following features (see Fig. 3.2).Container holding racks are carried into the re-tort and xed to a metal frame, which can be ro-tated at variable speed to increase heat transfer. Theretort door with bayonet-lock cannot be opened un-der inside overpressure. An insulated upper reservoirserves as storage for hot water at the endof the heatingperiod. Automatic control provides for uniform rep-etition of sterilization cycles. Temperatures and heattreatment equivalent are registered. Heating is pro-vided by steam(injection or heat exchanger), coolingby water.Vertical retorts had been used up to the second halfof the last century.48 Part I: Processing TechnologyFigure 3.2. A horizontal retort with hot water reservoir and mechanism for the rotation of containers.Continuous Pasteurizers andSterilizers for Food in ContainerTreatmentContinuous operation is advantageous in those plantswhere large volumes are processed for a long period.The specic energy and water consumption of a con-tinuous apparatus would be less than in its batch-typeequivalent.In tunnel pasteurizers horizontal conveyors carrycontainers through insulated heating and cooling sec-tions. Hot- and cold-water spray, sometimes com-bined with water baths, would be applied in counter-current ow to container travel. Atmospheric steamis also used (see Fig. 3.3).In combustion heated pasteurizers, cylindricalcans are rolled above gas-burners along guide-paths(Rao and Anantheswaran, 1988).1 23 48 7 6 594050 C 8095 C 5060 C 4050 C3040 C20 C 11 10Figure 3.3. Tunnel pasteurizer with hot- and cold-water spray: (1) container feed, (2) section for preheating,(3) maximum temperature zone, (4) zone of counter-current cooling, (5) container discharge, (6) cold-water section,(7) tepid water section, (8) medium hot water cooling section, (9) spray-nozzles, (10) water pump, and (11) lter tothe pump (altogether six units).3 Fruit Processing 49987654321HFigure 3.4. Hydrostatic sterilizer: (1) container feed,(2) container holding shell, (3) conveyor, (4) watercolumn for heating, (5) room under steamoverpressure, (6) water column for cooling atdecreasing pressure, (7) U-shaped cooling bath, and(8) discharge section of the conveyor.Hydrostatic sterilizers are the best energy and wa-ter saving devices with safe operational characteris-tics. Containers enter and leave the heating chamberthrough hydrostatic columns (see Fig. 3.4).The hydrostatic pressure at the bottom level of acolumn balances the chambers overpressure:p = Hg. (3.1)For example, if column height (H = 24 m) bal-ances a chamber pressure ( p = 230 kPa), thenthe saturated steam temperature is T = 125C. Suchsterilizers protrude from the plant building as a (in-sulated) tower.It is possible to reduce the height of the sterilizer byapplying serially connected lower columns on boththe inlet and outlet sides. Such construction needsspecial control systems on both sides. Hungarianconstruction with the commercial name Hunisterworks with six 4 m high columns (equivalent to a24 m high unit) and can be placed into a processinghall of about 8 m inner height (Schmied et al., 1968;P atkai et al., 1990).Pasteurizers and sterilizers with a helical pathand can-moving reel (commercial name: Steril-matic) are popular in the United States. Heatingand cooling units are serially connected in the nec-essary number. Cans rotate or glide along the heli-cal path. Cylindrical units are equipped with feedingand discharge devices, and special rotating valvesserve for units under inside overpressure. The hor-izontal arrangement is favorable. The long produc-tion and maintenance praxis of machinery coun-terbalance the drawbacks of somewhat complicatedmechanisms.Statements for Both Batch-Typeand Continuous ApparatusThe output of an apparatus, i.e., the number of con-tainers pasteurized in unit time (Q) can be calculatedby the formula:Q = WVtm, (3.2)W is the inside volume lled with containers, heattransfer mediums, and the transport mechanism. Thesymbol tm denotes the total treatment time, i.e., cy-cle period for batch type and total residence time forcontinuous operation. Vis the volume of a single con-tainer. is the compactness ratio, i.e., the volume ofall containers per inside volume. Greater and shorttm are advantageous and mean better compactnessand heat transfer intensity (including the use of ele-vated temperatures).The process diagram (see Fig. 3.5) presents ambi-ent and container temperatures and pressures depend-ing on treatment time (0 t tm) for a sterilizer.Treatment time is the time needed for the progress ofthe container in a continuous unit. Instrumentationenables quick creation of such diagrams.50 Part I: Processing Technologyt, min 10 20 30 40 050100TTK'CCPPK'bar332211B A C D4Figure 3.5. Process diagram of a hydrostaticsterilizer: (1) ambient temperature (TK), (2) centraltemperature in the food (TC), (3) ambientpressure (pK), and (4) pressure in the container (p).(AD) Heating (rising temperature), constanttemperature, rst cooling section, and second coolingsection, respectively.Table 3.2 presents specic energy and water re-quirements of a heat treatment apparatus, as thesemake a considerable contribution to the total con-sumption of a plant. Reduction can be achieved byheat recuperation and water reuse (ltration, disin-fection, etc.).Flow-Through Type Pasteurizersand SterilizersTypical ow-through type equipment consists of apump which propels liquid food through heating,constant high temperature, and cooling units for(aseptic) lling and sealing (see Fig. 3.6).Low viscosity liquids are apt to be moved throughtubular or plate heat exchangers. Fruit pulps, purees,and other comminuted fruits (containing occasion-ally dispersed particles) would be processed in unitsprovided with mixers and forwarding devices likescraped surface heat exchangers.Well-designed equipment consumes energy andwater with the same lowspecic values as hydrostaticsterilizers (see Table 3.2). Pulpy, brous juices andconcentrates belong to the pseudoplastic or plasticcategory of non-Newtonian uids. In addition to owresistance and heat transfer calculations, the resultsof (chemical) reactor techniques should be adoptedfor quality attribute change calculations, includingthe inactivation of enzymes and microbes. Such con-cepts as residence time distribution of food elements,macro- and micro-mixing, etc., are involved here.Special problems arise fromundesirable deposits andburning on the food side of heat transmission walls.Table 3.2. Specic Consumption of Steam (400 kPa, Saturated) and Water (About 20C) of HeatTreatment ProcessesPasteurization orSterilizationProcess (Notes)Specic Consumption (kg/kg)Equipment (Notes) Steam WaterFood in container treatment Tank pasteurizer 0.400.55 48(values are related to the Vertical retort (without heat 0.200.36 24mass of food + container) recuperation); horizontal retort(with heat recuperation)Tunnel pasteurizer 0.150.20 1.52Hydrostatic sterilizer 0.080.12 1.22Flow-through type treatment(values are related to theTubular and plate apparatus (withoutheat recuperation)0.120.18 mass of food) Tubular and plate apparatus (with heatrecuperation)0.060.12 3 Fruit Processing 51123456Figure 3.6. Flow-through type pasteurization: (1) feed tank, (2) pump, (3) scarped surface heat exchangers,(4) isolated tube for keeping the food at constant temperature, (5) scarped surface cooling units, and (6) aseptictank for pasteurized food.HEAT PROPAGATION UNDERHEAT TREATMENT CONDITIONSHeat Conduction in Food HoldingContainersExperience has shown that heat propagation in manyfood materials under the circumstance of pasteuriza-tion can be calculated using the principles of conduc-tion. All food products might be treated as conduc-tive, in which no major convective currents developduring heat treatment. Small local movements fromdensity differences or induced vibrations increase theapparent thermal diffusivity. As a consequence, thebest way to measure thermophysical constants is bythe in plant method. Results of in plant measure-ments are often 1020% higher than respective datafrom the literature (P atkai et al., 1990). The calcula-tion of time-dependent temperatures in food is basedon the differential equations of unsteady-state heatconduction with initial and boundary conditions. Theapplication of the Duhamel theory is also needed incase of time-dependent variation of the retort temper-ature (Geankoplis, 1978; Carslaw and Jaeger, 1980).While analytical solutions are limited to a fewsim-plied tasks, a wide range of industrial problems canbe solved using methods of nite differences and -nite elements. Figure 3.7 illustrates the elementaryannuli (and cylinders) of a cylindrical can. Figure 3.8illustrates a time-dependent change in ambient tem-perature and the approximation using step-wise vari-ation. Both gures explain a nite difference method,where differential quotients have been substituted byquotients of suitably small differences (K ormendy,1987).52 Part I: Processing TechnologyFigure 3.7. Geometry belonging to anite difference method. (AI)Elementary annuli and cylinders. Bia,Bib, Bip: Biot numbers (bottom, cover,and jacket, respectively).t1 tjtjtj+1t'jTR,1TR,jTR, j+1TR Ct, minFigure 3.8. Retort temperature (TR)and its step-wise approximation in anite difference calculating system.Hollow circles illustrate input data(temperature vs time). Time intervals(tj) are divided into sufciently smallequal time steps (t

j).3 Fruit Processing 53Natural and Forced ConvectionHeating of Food Holding ContainersNatural convection heat transfer inside containers isbased on uid circulation induced by temperatureand density differences. The phenomenon is typi-cal for lowviscosity liquids. Temperature differencesare the greatest at the container wall, while the cen-tral bulk is of near uniform temperature. Practicalcalculations are based on a heat balance includingthe mean temperature of food and ambient temper-ature. The relation Nu = C (Gr Pr)mbetween di-mensionless terms (groups) can be applied for thefrom wall to food heat transfer. Treatment time isdivided into consecutive intervals to enable the use oftemperature-dependent physical constants for com-puter analysis. The result is the time-dependent aver-age temperature in the container (K ormendy, 1987).The expression of forced convection would be ap-plied to all those achievements, where the effect ofmixing is gained by mechanical energy input into auid, slurry, or paste. The rate of heat ow may beincreased considerably by mixing the food in a con-tainer. Actual accomplishment of mixing is done byrotating or tilting the containers. Machines often ro-tate the containers as a consequence of conveyance.Some hydrostatic sterilizers incorporate periodic tilt-ing. The rotational speed or tilting rhythm dependson the conveyance speed in this equipment.Anumber of rotational speeds are available in hor-izontal retorts. Frictional, gravitational, and inertialforces and their (periodic) variation acting on ro-tating food elements jointly inuence mixing. Thevolume of the headspace also inuences the mixingeffect (K ormendy, 1991). An optimum speed exists,because at high rotational speed the mixing effect de-creases as the food reaches a new equilibrium stateunder the overwhelming centrifugal (inertial) force(Eisner, 1970).Many products contain fruit pieces in a syrup orjuice. Heat is transferred from the container wall intothe uid constituent by convection, while the fruitpieces are heated by conduction. Time-dependenttemperatures are obtained by using equations for con-vection and conduction, including initial and bound-ary conditions (Bimbenet and Duquenoy, 1974).Heat transfer coefcients have been developedthrough extensive research. Results are heat trans-fer coefcients from container wall to liquid foodand from liquid food to pieces of food, depending oncontainer geometry, rotational speed, product, andheating and cooling programs. Coefcients take intoconsideration the relationship between dimension-less terms (Bi, Gr, Nu, Pr, Re, St, We), geometri-cal proportions, and temperature and viscosity ratios(Rao and Anantheswaran, 1988; Rao et al., 1985;Sablani and Ramaswamy, 1995; Akterian, 1995).The usual methods based on the determinationof the values: fh, jh, fc, jc (Ramaswamy andAbbatemarco, 1996) are adequate for convective heattransfer calculations (if proper simulation has beenused in case of forced convection). For conductiveheating, however, it seems advisable to use the pre-vious values for the evaluation of the relevant ther-mophysical constants and enter the latter values intoa computer program that calculates with the help ofnite differences.Heat Transfer in Flow-Through TypeHeat Treatment UnitsWhen liquid food (including non-Newtonian slurriesand purees) is pumped through channels (tubular, an-nular, and plate-type heat exchangers), three majorow types would form: sliding (peristaltic), laminar,or turbulent. Heat transfer calculations are availablefor all three types of publications from the unit oper-ations eld (Geankoplis, 1978; Gr ober et al., 1963).Relationships between dimensionless terms are ap-plied as previously described.A number of publications are available on scrapedsurface heat exchangers, including heat transfer char-acteristics (Geankoplis, 1978).LOAD AND DEFORMATION OFCONTAINERS UNDER HEATTREATMENT CONDITIONSContainers and TheirCharacteristic DamagesThe main load on containers under heat treatmentconditions originate from the difference in ambientand inside pressure. The deformation or damage thatoccurs from this load depends on the geometry andmaterial of the container, the design of closure, andthe headspace volume.Metallic containers display reversible deforma-tion at small loads and permanent deformations athigher loads (see Fig. 3.9). Excess inside overpres-sure causes permanent bulging at the end plates ofa cylindrical can, while outside overpressure mightindent the jacket.54 Part I: Processing Technology51015200.1 0.3 0.4 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9p(bar)515202530354045505560V(cm3)Figure 3.9. Volume change (V)versus pressure difference (p) relationof a tinplate can.Rigid containers like glass jars and bottles undergovery small (and resilient) deformation. Excess insideoverpressure can open or cast down the cover. Thetemporary opening of the cover effects air exhaustor food loss, depending on the position (vertical orhorizontal) of the jar.Plastic bags are susceptible to large deforma-tions, while inside overpressure easily rips the bags.Table 3.3 includes critical loads for some types ofcontainers.Deformation Versus LoadCalculationsTwo basic equations are used to calculate the insidepressure of a container, the respective pressure dif-ference, and container volume:p = pf+ RTGVGn

i =1mGiMi= pf+ TGVGTG0( p0 pf0) , (3.3)andVG = VC0 [1 +VC (TC TC0)] +V Vf0[1 +Vf (Tf Tf0)] . (3.4)Additional relationships and data are needed astime-dependent variations of ambient pressure andtemperature, temperatures of the container wall,headspace, and food (average). Initial values (at themoment of closing) include volumes, pressures, andtemperatures. According to Equation 3.3, the insidepressure of the container is the sum of the vaporpressure of food and of the partial pressure of gascomponents. According to Equation 3.4, the actualheadspace volume (VG) can be calculated by addingthe container volume (increased exclusively by heatexpansion) to the pressure difference induced volu-metric container deformation (V), and subtractingthe volume of food expanded by heat. The measuredrelationship between V and the pressure difference(p, e.g., see Fig. 3.9) is also required for the formula(K ormendy and Ferenczy, 1989; K ormendy et al.,1994, 1995).3 Fruit Processing 55Table 3.3. Critical Loads of Tinplate Cans and Glass JarsContainer Critical load (kPa)Material V0 d j ep p1 p2 NotesTinplate can 860 99 0.180.220.240.180.220.24103138159526067p1: bulgingof end plates32004760153 0.280.300.30.3275954353p2:indentationat the jacket6830 160 0.28 0.3 78 51Glass jar +twist-off lidof tinplate 79 0.24 107 p1: openingof the lidNote: V0volume (cm3); jjacket thickness (mm); dcan diameter or lid diameter for jars (mm); epend plate thickness orlid plate thickness (mm).QUALITY ATTRIBUTE CHANGESAttribute KineticsBesides the concentration of favorable and unfavor-able constituents, enzyme activity, sensory attributes,related physical properties, etc., the concentration ofsurviving microbes can also be regarded as a qualityattribute. Namely, similar descriptive kinetic meth-ods, concepts of extreme values andaverages are usedfor changes in microbial concentration.The typical method to measure variations of time-dependent attributes in food is by laboratory testing ata number of different constant temperatures, provid-ing for all major conditions of (industrial) heat treat-ment. The next step is the tting of expertly chosenrelationships to data, and the simultaneous evaluationof kinetic constants.Heat inactivation of microbes belongs to the popu-lationchange dynamics eld. Since earlyyears (about1920), rst-order equations had been used, mean-while, a number of other equations were also tted toexperimental results (Casolari, 1988; K ormendy andK ormendy, 1997). The method that shows promiseis based on the distribution of lethal time of the in-dividual microbes combined with the two paramet-ric Weibull distribution (Peleg and Penchina, 2000;K ormendy and M esz aros, 1998). The Weibull distri-bution is useful for tting to diverse types of time-dependent inactivation courses by selecting appro-priate constants.The generally used rst-order (exponential)equations areN = N010t /D, (3.5)andD = Dr10(TTr)/z. (3.6)The rst equation is valid for constant temperature,the second one describes the variation of the deci-mal reduction time (D) versus temperature (T). Dr,Tr are arbitrary (though expedient) reference values.Time-dependent variationof the logarithmof the con-centration of surviving microbes is linear. The valueof z is the temperature increment effecting the deci-mal reduction of D. Naturally, D is not the decimalreduction time in non-exponential relationships.Reaction theory principles should be used to deter-mine changes in time-dependent chemical concen-trations (Levenspiel, 1972; Froment and Bischoff,1990). However, mostly tted relationships are usedinstead of more exact calculations. Kinetic constantsare: rate constant (k, or rate constants), energy of acti-vation (Ea), reference temperature (Tr), and referencerate constant (kr). The rate constant is independentof the initial concentration if the kinetic equation isbased on a sound chemical background, otherwise atted rate constant might only be valid for a xed ini-tial concentration (see more details in the publicationof K ormendy and M esz aros, 1998).Empirical (i.e., tted) equations describe the time-dependent variation of sensory attributes and of re-lated physical properties (color, consistency, etc.).Concentration based attributes follow a linear mix-ing law, i.e., the attribute intensity of a mixture of dif-ferent volumes and intensities is the weighted meanof component intensities. This evident rule is notvalid for sensory attributes (see K ormendy, 1994; forfood color measurements).56 Part I: Processing TechnologyAttribute Intensity VersusTime-dependent Temperaturein Food Holding ContainersTemperature always varies during a heat treatmentprocess (see Fig. 3.5). No general procedure existsfor calculating time-dependent attribute intensity atvariable temperature from constant temperature ex-periments. Notwithstanding, a few useful methodshave been developed since about 1920 and more areexpected in the future.The equivalent sterilization time (F) at constantreference temperature (Tr) induces the same lethaleffect as the actual time-dependent temperaturevariation:F =tm

010T(t )Trz dt. (3.7)The previous integral was used later for pasteuriza-tion (P), enzyme inactivation (E), chemical and sen-sory attribute variation (C), replacing the symbol Fby P, E, C(cooking value), respectively. Equation 3.7had been derived originally for rst-order (i.e., ex-ponential) destruction. It could be proved later thatEquation 3.7 is applicable in all those cases, where at-tribute intensity at constant temperature depends onlyon t/Dor kt. There are methods for other variable tem-perature changes (K ormendy and K ormendy, 1997;Peleg and Penchina, 2000). Equations 3.6 and 3.7undergo modications, when the z-value is replacedby the energy of activation (Hendrickx et al., 1995).The attribute intensity at the end of a process is eas-ily available by substituting Tr, Dr (or kr) and theequivalent time (F, P, E, C) into the constant temper-ature intensity versus time relation [e.g., into Eq. 3.5].Computerizedcalculationshouldprovide three inten-sities in a container: the maximum, the minimum, andthe average (see Background of Microbial Safetyand Table 3.1). The cold point of a vertically posi-tioned container is near the bottom, at a distance lessthan 25% of the container height, in case of naturalconvection.Calculation Methods forFlow-Through Type ApparatusThe residence time is uniform for all food elementsin case of in-container pasteurization. As a contrast,4.1023.1022.1021.10200.10.20.3E (t)min1E (t)exp (kt).E (t)exp (kt).E (t)exp (kt).E (t) dttp5 10 t, min0Figure 3.10. Average attributeintensity at the discharge valve of aow-through type unit. E(t ) =time-dependent density (frequency)function of the residence timedistribution, k = rst-order rateconstant, exp(kt ) = time-dependentintensity variation per initial intensity.The denite integral gives the averagedischarge intensity per initial intensity,illustrated by the hatched area. tp, :dead time and expectation value ofE(t), respectively.3 Fruit Processing 57food elements reside for different time intervals in aunit of a ow-through type apparatus, and a distribu-tion function characterizes residence time. A sampleat the discharge port of a unit is a mixture of foodelements of different residence time intervals. It hasbeen proved for liquid food that the average of theconcentration of surviving microbes at the exit canbe calculated according to the equation:N = N

0E(t ) 10t /Ddt , (3.8)if food temperature is constant (suspended parti-cles are small enough too) and exponential inac-tivation law exists [see Eq. 3.5]. Equation 3.8 isbased on macromixing principles (Levenspiel, 1972)and can be easily converted for other inactiva-tion kinetics. Figure 3.10 demonstrates the essenceof calculation useful for a constant temperatureunit.No denite solution exists for a variable tempera-ture unit, presumably the approximation of Bateson(1971) will be useful in the future. As a consequenceof his idea, an average temperature (T) can be as-sessed for a variable temperature unit and the per-taining value: D substituted into Equation 3.8. Theheat treatment equivalent for average attribute inten-sity (F) is now:F = log NN0. (3.9)The overall equivalent of an apparatus with seriallyconnected units (e.g., heating, constant temperature,and cooling) is the sum of the individual units equiv-alents (K ormendy, 1994, 1996).LIST OF SYMBOLSBi Biot numberC dimensionless constantC cooking value (min)D decimal reduction time or time constant(min)D average of D (min)E enzyme inactivation value (min)Ea energy of activation (kJ/kmol)E(t) density function of the residence timedistribution (earlier: frequencydistribution, min1)fc, fh cooling and heating rate indexes: timeneeded for the decimal reduction of thedifference between outside and insidetemperatures (min)F sterilization or lethality value (equivalent,min)F average of Fg gravitational constant (m/s2)Gr Grashof numberH water column height (m)jc, jh cooling rate and heating rate lag factorsk rate constant (for rst-order kinetics,min1)m dimensionless exponentmG mass of a gas component (kg)M molar weight of a gas component(kg/kmol)n number of gas componentsN concentration of living or survivingmicrobes (cm3)N average of N (cm3)Nu Nusselt numberp absolute pressure in a container (kPa)P pasteurization value (equivalent, min)Pr Prandtl numberQ number of containers pasteurized in unittime (min1)R universal gas constant [kJ/(kmol K)]Re Reynolds numbers spoilage ratioSt Stanton numbert