freeze concentration review

http://fst.sagepub.com/International

Food Science and Technology

http://fst.sagepub.com/content/15/4/303The online version of this article can be found at:

DOI: 10.1177/1082013209344267 2009 15: 303 originally published online 15 October 2009Food Science and Technology International

J. Snchez, Y. Ruiz, J.M. Auleda, E. Hernndez and M. RaventsReview. Freeze Concentration in the Fruit Juices Industry

Published by:

http://www.sagepublications.com

On behalf of:

Consejo Superior de Investigaciones Cientficas (Spanish Council for Scientific Research)

can be found at:Food Science and Technology InternationalAdditional services and information for

http://fst.sagepub.com/cgi/alertsEmail Alerts:

http://fst.sagepub.com/subscriptionsSubscriptions:

http://www.sagepub.com/journalsReprints.navReprints:

http://www.sagepub.com/journalsPermissions.navPermissions:

http://fst.sagepub.com/content/15/4/303.refs.htmlCitations:

What is This?

- Oct 15, 2009 OnlineFirst Version of Record

- Nov 4, 2009Version of Record >>

at UNIV ESTDL DE PONTA GROSSA on November 3, 2013fst.sagepub.comDownloaded from at UNIV ESTDL DE PONTA GROSSA on November 3, 2013fst.sagepub.comDownloaded from at UNIV ESTDL DE PONTA GROSSA on November 3, 2013fst.sagepub.comDownloaded from at UNIV ESTDL DE PONTA GROSSA on November 3, 2013fst.sagepub.comDownloaded from at UNIV ESTDL DE PONTA GROSSA on November 3, 2013fst.sagepub.comDownloaded from at UNIV ESTDL DE PONTA GROSSA on November 3, 2013fst.sagepub.comDownloaded from at UNIV ESTDL DE PONTA GROSSA on November 3, 2013fst.sagepub.comDownloaded from at UNIV ESTDL DE PONTA GROSSA on November 3, 2013fst.sagepub.comDownloaded from at UNIV ESTDL DE PONTA GROSSA on November 3, 2013fst.sagepub.comDownloaded from at UNIV ESTDL DE PONTA GROSSA on November 3, 2013fst.sagepub.comDownloaded from at UNIV ESTDL DE PONTA GROSSA on November 3, 2013fst.sagepub.comDownloaded from at UNIV ESTDL DE PONTA GROSSA on November 3, 2013fst.sagepub.comDownloaded from at UNIV ESTDL DE PONTA GROSSA on November 3, 2013fst.sagepub.comDownloaded from at UNIV ESTDL DE PONTA GROSSA on November 3, 2013fst.sagepub.comDownloaded from

Review. Freeze Concentration in the Fruit Juices Industry

J. Sanchez,1 Y. Ruiz,2 J.M. Auleda,1 E. Hernandez1 and M. Raventos1,*

1Agri-Food Engineering and Biotechnology Department, Technical University of Catalonia (UPC)Avda, Canal Olmpic, 15, 08860 Castelldefels, Barcelona, Spain

2Chemical Engineering Department, Faculty of Engineering, National University of ColombiaCiudad Universitaria Cra, 30 No 45 26, Bogota, Colombia

In conventional processes, such as evaporation, higher levels of concentration can be reached comparedwith freeze concentration or membrane techniques. However, the advantage of the freeze concentrationtechnique is based on the quality of the product obtained due to the low temperatures used in the

process, which makes it a very suitable technology for the processing of fruit juices. There are two basicmethods for concentrating solutions by freezing: suspension and film freeze concentration. Suspensionfreeze concentration systems (FCS) already have operating equipment in the food industry, while filmFCSs, also called layer crystallization, is still at an experimental stage. This review summarizes the most

important studies relating to the suspension and film freeze concentration in fruit juices and sugarsolutions, illustrating the different possibilities that freeze concentration has in the fruit juices industry;it also presents trends and suggests improvements for the future development of this technology. It is noted

that most recent publications refer to the film FCS. The technology used to design, build and maintainlayer crystallization equipment is simple and it can be available to any operator in the food industry, layersystems will be used in the future if their results can be improved in terms of ice purity and degree of fluid

concentration.

Key Words: freeze concentration, suspension system, layer concentrators, fruit juices, sugar solutions

INTRODUCTION

The growing demand for fruit juices of high sensory

and nutritional quality has led to the search for new or

improved food processing technologies. Among the

techniques for concentration of liquid foodstuffs,

freeze concentration is of particular interest due to the

low temperatures used in the process.Freeze concentration is a technology that can be used

in the food processing industry to concentrate fruit

juices (Rahman et al., 2006). This process allows

removal of water from a solution by cooling or freezing

it until high-purity ice crystals are formed and separated

to leave a concentrated fluid. The nutritional and sen-

sory quality of freeze-concentrated fruit juices is higher

than those concentrated conventionally by means of

evaporation due to the low processing temperatures,

which avoid undesirable chemical and biochemical

changes, and minimize the loss of sensory properties.

Some authors have summarized the studies referring tothe concentration of fruit juices as cryoconcentration,however the subject is treated in general, making com-parisons with other methods for the concentration ofjuice (Ramteke et al., 1993) and with emphasis on thedescription and operation of equipment involved in theprocess (Deshpande et al., 1984).The objectives of this paper are to summarize the

most important studies relating to the suspension andfilm freeze concentration in fruit juices and sugar solu-tions, present trends and suggest improvements for thefuture development of this technology.

FREEZE CONCENTRATIONMETHODS

According to various researchers (Muller andSekoulov, 1992; Flesland, 1995; Chen et al., 1998;Miyawaki, 2001; Wakisaka et al., 2001), there are twobasic methods for ice crystal formation in solutions. Thefirst is known as suspension crystallization (Huige andThijssen, 1972; Hartel and Espinel, 1993), consisting ofan initial phase of ice nuclei formation (nucleation), alsocalled crystallization, followed by a second phase whichinvolves the growth of ice nuclei in the solution(Figure 1(a)). The second method is the crystallization

*To whom correspondence should be sent(e-mail: [email protected]).Received 23 March 2009; revised 3 June 2009.

Food Sci Tech Int 2009;15(4):0303315 SAGE Publications 2009Los Angeles, London, New Delhi and SingaporeISSN: 1082-0132DOI: 10.1177/1082013209344267

303

of water present in the solution in form of an ice layer on a

cold surface (Muller and Sekoulov, 1992; Flesland, 1995;Figure 1(b)).In the industry, suspension freeze concentration con-

sists of three stages: crystallization, growth and separa-tion of ice crystals, performed with specially designedequipment for each purpose. The system comprises thefollowing equipment (Lemmer et al., 2001; Jansenet al., 2001; Verschuur et al., 2002; van Nistelrooij,2005): a scraped-surface heat exchanger (SSHE;Figure 2) and a recrystallizer. The SSHE forms ice

nuclei at high supercooling and low residence times,where ice nuclei are formed on the inner surface of theheat exchanger and then are scraped off by rotatingblades. The ice nuclei go to the recrystallizer (Figure 2)for ice crystal growth based on the Gibbs Thomsoneffect and then a separation of ice crystals from the con-centrate occurs normally in a pressurized wash column(Figure 2). In this system, ice crystals of high purity can

be attained (Thijssen, 1986).

The second system, film freeze concentration,

consists of formation of a single crystal, which growslayer by layer from the solution to be concentrated.The crystal growth (dendrites) tends to be paralleland opposite to the direction of heat transfer(Flesland, 1995) The crystal adheres to the cold surfaceduring the process, facilitating separation of the twophases (Figure 3).This concentration system is based on directional

freezing, and the most important crystal form is thedendrite (Flesland, 1995; Chen et al., 1998; Chen

and Chen, 2000; Pardo et al., 2002; Gu et al., 2005;Caretta et al., 2006). Heat transfer rates are normallygreater than mass transfer rates, due to the high ther-mal conductivity of ice and low mass diffusion coeffi-cients. Therefore solute diffusion will be the limitingfactor for ice growth, and supercooling (constitutionalsupercooling) in the tip region will be observed (Rutterand Chalmers, 1953; Ozum and Kirwan, 1976; Teraoka

et al., 2002; Hindmarsh et al., 2005; Ayel et al., 2006).

Ice crystal Ice nuclei

Concentrate

Concentrate

Ice layer

Cold surface

(a) (b)

Figure 1. Two methods for concentration by freezing.

Feeding tank

Nucleation (crystallization)scraped-surface heat exchanger (SSHE)

Concentrate

Growthrecrystallizer Heater

Water

Separationwash column

Figure 2. Schematic suspension freeze concentration system (courtesy of Niro Process Technology).

304 J. SANCHEZ ET AL.

Solute inclusion in ice is difficult to avoid in practical

applications, especially for solute concentrations of

commercial interest for freeze concentration, which

means between 20% and 50% of dissolved solids

(Flesland, 1995). The two methods described for the for-

mation of ice in solutions differ in terms of heat extrac-

tion, ice growth rate, ice purity, equipment, industrial

process, solidliquid contact surface, and necessaryinvestment (Table 1).

SUSPENSION FREEZECONCENTRATION

Research in suspension freeze concentration hasfocused on two issues: control of nucleation andgrowth of ice crystals to obtain large ice crystals, pref-erably of uniform size, and to separate ice crystals selec-

tively from the concentrate. According to Thijssen(1986) and Hartel and Espinel (1993) this systemrequires separate stages for nucleation and growth ofice crystals since the optimal operating condition

requirements for these distinct crystallization phenom-ena can be significantly different.The studies using juices have a wide range of aims,

including examination of the basis of the process(Omran and King, 1974; Stocking and King, 1976;

Thijssen, 1986; Chiampo and Conti, 2002) and determi-nation of the sensory quality of the juices obtained (VanWeelden, 1994; Lee and Lee, 1998). Those studies showthat the final concentrations attained by this method

vary between 45 Bx and 55 Bx.

Crystallization

The study of suspension freeze concentration has

shown that in fruit juices and sucrose solutions themost important category of nucleation is secondaryrather than primary nucleation (Omran and King,1974). For that reason, some researchers have studied

that aspect in greater depth to understand the mechan-isms that give rise to secondary nucleation and manymodels have been generated to represent its kinetics.That is the case with the studies performed by

Stocking and King (1976), who found that the velocityof nucleation and rate of growth depend on the super-cooling of the system and established that a model basedon a power law can be used to represent the relationship

between those variables for sucrose solutions, orangejuice and apple juice. They also found that crystalgrowth at high supercooling occurs dendritically or

with a needle shape, which gives rise to a larger surfacearea and greater difficulty of separation from the con-centrated solution. In highly concentrated sucrose solu-tions the nucleation rate is independent of the

concentration of the solution and as the concentrationof a sucrose solution increase the rate of crystal growthdeclines due to greater viscosity. In studies using sugarssuch as dextrose or fruit juices, Thijssen (1975) found

that the rate of nucleation increases with the concentra-tion of dissolved solids and is proportional to the squareof the supercooling of the sine of the solution, and alsothat the presence of localized supercooling in the crystal-

lizer due to nonuniform mixture gives rise to an increasein the rate of nucleation, so that the presence of such

Refrigerant

Expansion valve

Distribution juice duct

Ice layer

Liquid food falling film

Evaporator

Refrigerant

By-pass

Pump

Tank

Figure 3. Schematic film freeze concentrationsystem (Raventos et al., 2007).

Table 1. Indicative data of film and suspensioncrystallization systems.

Filmcrystallization

Suspensioncrystallization

Heat extraction Through ice layer Through solutionIce growth rate 106107 (m/s)a 107108 (m/s)b

Ice purity Low HighEquipment No moving parts

except pumpingequipment

Moving partsin all theequipmentare needed

Industrial process Discontinuous ContinuousSolidliquidcontact surface

Low High

Percentage of neededinvestmentc

100 150250

aOlowofoyeku et al. (1980); Flesland (1995); Chen et al. (1999); Miyawakiet al. (1998).bHuige and Thijssen (1972); Hartel and Espinel (1993); Chiampo and Conti(2002).cFlesland (1995).

Review. Freeze Concentration in the Fruit Juices Industry 305

points should be avoided in the interest of controllingthe average size of the crystals formed.Huige and Thijssen (1972) developed the basic

knowledge of the suspension freeze concentrationprocess (Table 2) involving supersaturation in a crystal-lizer with continuous seeding of small crystals that dis-solved and promoted the growth of larger crystalsalready present in the crystallizer (Ostwald ripeningmechanism).Another method of increasing the size of ice crystals

has been presented by Shirai et al. (1987) andKobayashi et al. (1996). The authors have used agglom-eration to increase the ice crystal size in order toimprove the solidliquid separation. Kobayashi et al.(1996) concluded from storage experiments (Table 2)that agglomeration of ice crystals mainly depends onthe seed crystals, the initial crystal size distributionand the concentration of solute. Extensive agglomera-tion of ice crystals was observed in glucose solutionswith concentrations of 10% and lower, but not in solu-tions with concentrations of 20 and 30%.More recently, Pronk et al. (2002) confirms that the

Ostwald ripening mechanism in ice suspensions is themost important for crystal size. Agglomeration isobserved in some cases but this mechanism plays aminor role. A computer-based dynamic model ofOstwald ripening in ice suspensions has been conductedto simulate the development of ice crystal size distribu-tions during adiabatic ice slurry storage (Pronk et al.,2005). Validation with experimental results for differenttypes and concentration of solutes (sucrose solutions),different ice fractions and different mixing rates showed

that the model is able to predict the development of theaverage crystal size in time.Bayindirli et al. (1993) carried out studies for formu-

lation of a mathematical model to describe the freezeconcentration of apple juice (Table 3), concluding thatthe kinetic of the cryoconcentration process fits to asigmoidal curve. A similar behavior of the concentrationkinetics can be found in the work of Nonthanum andTansakul (2008) during the process of cryoconcentrationwith lime juice. Chiampo and Conti (2002) presented theresults obtained in a freeze concentration pilot plant ofNiro Process Technology (Table 3), using strawberryjuice and other kinds of sugar solutions (sucrose solu-tions at different initial concentrations). It was foundthat for an optimal functioning of the equipment, themaximum amount of ice in the re-crystallizer must notexceed 40% and secondly that the average speed of icegrowth is lower in the strawberry juice than in the sugarsolutions. The ice productivity of the equipment is lowerwith strawberry juice than with the sugar solutions, witha maximum of 150 kg /h/m3.

Separation of Ice Crystals

The separation of ice crystals from concentrated fruitjuices can be performed using presses, centrifuges, andwash columns, operating either in batch or in continu-ous mode. Both presses and centrifuges present pro-blems with carry-over of the product, whereas washcolumns have been developed to the point where thesolute inclusions have been reduced to less than100 ppm. Several types of wash columns have been

Table 2. Some studies including suspension freeze concentration of sugars.

Fluid, author andyear of publication Aim of study Equipment Results

Sucrose solutions(Huige andThijssen, 1972)

To describe (by means of amathematical model) a newbulk crystallization processstudied experimentally for thegrowth of ice crystals fromaqueous sucrose solutions.

Crystallizer (SSHE) The model predicts an increase of the meansize of the product crystals with a decreaseof feed crystal size for small feed crystals.The size of the product crystals alsoincreases with an increase in crystal con-centration in the crystalliser.

Glucose solution(Kobayashiet al., 1996)

To develop an easier methodto produce large ice crystalsagglomerated in a commonbatch crystallizer with aninner heat exchanger.

Experimental apparatusbased on that proposedby Shirai et al. (1987)

To make large agglomerated ice crystals: Keepthe initial supercooling, i.e., the temperaturedifference between the lowest temperatureinitially attained and the freezing point of thesolution less than 0.2 K and introduce seedice crystals greater than 6% of the solutionweight to trigger the ice crystallization.

Sugar solutions(Qin et al., 2006)

To measure the heat transfercoefficient and the powerconsumption of a laboratorySSHE used for freezinga sugar solution.

SSHE Heat transfer coefficient with phase change (iceformation) is about three to five times greaterthan that without phase change.Power consumption increased synchro-nously with the ice fraction in the processfluid mainly due to the fluidity reduction(or the apparent viscosity increase) of iceslurry.


developed and put into industrial application and theydiffer in the various crystal bed transport mechanisms(Verdoes et al., 1997), where the crystal can be trans-ported by either gravity, mechanically (piston/screw), orhydraulic pressure. The last two are known as washcolumns with forced transport. For more than two dec-ades the gravity-type units were the only commerciallyavailable ones, since problems with scale-up and theeffect of back mixing on product purities have limitedtheir commercial application. Forced transport washcolumns are smaller and operate with short residencetimes; crystals obtained are relatively pure and strongenough so that a wash column with forced transport

will be preferred over a gravity wash column. (Scholzet al., 2002).The most commonly used wash column for freeze

concentration systems (FCS) in the fruit juices industryis the piston-type wash column in countercurrent wash-ing (van Nistelrooij, 2005; Morison and Hartel, 2006).

Quality

Studies performed in the 1980s and early 1990s focusedon assessment of the quality of the products obtained,such as in the studies with pineapple and orangejuice carried out by Braddock and Marcy (1985; 1987).

Table 3. Studies that include suspension freeze concentration of fruit juices.


Apple juice, orange juice,sucrose solution, glucosesolution, fructose solution(Omran and King, 1974)

To study secondary nucleationkinetics with fruit juices andsugar solutions.

Crystallizer withcooling bath andglass stirrer.

The nucleation order is independent of sugarconcentration, type of sugar, and stirring rate.

The nucleation rate order is a strong function ofthe sugar concentration.

Apple juice, orange juice,sucrose solution, glucosesolution, fructose solution(Stocking and King, 1976)

To study ice nucleation rates infruit juices, sugar solutions,and distilled water.

Crystallizer cell withcooling bath andglass stirrer.

Nucleation rate in sugar solutions and fruit juicesincreases with approximately the secondpower of subcooling.

Pineapple juice (Braddockand Marcy, 1985)

To examine pilot scaleprocessing parameters andproduct quality aspects offreeze concentration appliedto fresh pineapple juice.

Suspension pilotequipment (ModelW-8, GrencoProcessTechnology).

Flavor of reconstituted freeze concentrated juicewas comparable to single strength juice andpreferable to evaporator concentrated juice.

Orange juice(Braddock andMarcy, 1987)

To determine the effects ofheat inactivation of enzymesand pulp content on quality offreeze concentrated orangejuice.

Suspension pilotequipment (ModelW-8, GrencoProcessTechnology B.V).

Except for considerable pulp reduction of feedstream juices, there were few differencesfrom normal citrus juice recovery proceduresfor freeze concentration (the product retainedmost of the aroma constituents of fresh juice).

Orange juice(Thijssen, 1986)

Grenco freeze concentration iscompared with evaporationand hyperfiltration.

Grenco ProcessTechnology B.V.cryoconcentrator.

Freeze concentration appears an attractivemethod: Conservation of nutritional andorganoleptic characteristics of fresh product,the net added value must be based on thepackaged product (production costs makes arelatively small contribution of the processingcosts to the total costs of the packagedproduct).

Apple juice(Bayindirli et al., 1993)

To study apple juice cryocon-centration in a single-stageprocess and a multi-stageprocess.

Hemispherical por-celain containers.

At the end of the single-stage experiments onlya double concentration could be achieved.With multi-stage experiments higher concen-tration levels could be achieved.

Sugar cane juice, sucrosesolution (Patil, 1993)

To examine freezing points, visc-osities, and changes withconcentration of raw and clearcane juices.

Crystallizer cell with acooling jacket.

The freezing points of raw juices are lower thanthose of sucrose solutions.

The maximum juice concentration was limited toabout 54 Bx.

The decrease in crystal size with increasingconcentration and the high viscositiesobserved would make it impractical to usefreezing to increase the Brix value beyondabout 50 Bx.

Strawberry juice andsugar solutions(Chiampo andConti, 2002)

To present the results obtained infreeze concentration of fruitjuices at a pilot plant.

Pilot plan implemen-ted for NiroProcessTechnology B.V.

Speed of ice growth in strawberry juice islower than the speed obtained for sucrose-water solutions.

Maximum specific yield, dependent on the con-centrated product (150 kg/h/m3)


They compared the aroma and flavor of fresh juicewith those of freeze concentrated juice and vacuumevaporation concentrated juice (Table 3), finding thatthe freeze concentrated juice preserved its sensory quali-ties better in comparison with the juice concentrated byevaporation.During the 1990s and the early years of the new cen-

tury, there were references using fruit juices, some aimedat studying the sensory qualities of juices obtainedthrough suspension freeze concentration (VanWeelden, 1994; Lee and Lee, 1998). Lee and Lee(1998) examined changes in quality during the refriger-ated storage of clarified pear juice at 10 Bx obtained byvacuum evaporation, reverse osmosis and cryoconcen-tration. The results indicated that after 10 days of stor-age there are no significant differences in browning andturbidity. Juices obtained by reverse osmosis and cryo-concentration show a similar sensory quality and it issuperior to that obtained by evaporation.

RECENT DEVELOPMENTS ANDPOTENTIALS TRENDS

More recent studies have aimed at improving thestages in commercial equipment of suspensionfreeze concentration (Niro Process Technology,The Netherlands; Figure 2).Very little information is available regarding the ice

crystallization process in scraped surface ice generators(SSHE) and most theories of ice crystallization mechan-isms largely depend on anecdotal evidence and aresomewhat speculative (Hartel, 1992; Stamatiou et al.,2005). Schwartzberg (1990) proposed that dendritesgrow out from the wall into the bulk solution due tothe large temperature gradient present at the wall sur-face by some heterogeneous mechanism and are subse-quently scraped off by the rotating blades. It is possiblethat ice crystal fragments that remain on the wall afterthe scraper blade passes are the source of new crystalsthat form along the wall between scrapes (Drewett andHartel, 2007). Ice fragments that break off provide sec-ondary nuclei and can result in formation of new crys-tals through a contact mechanism.In a recent work, Qin et al. (2009) studied and mod-

eled ice nucleation from aqueous solutions on a sub-cooled solid surface. The most important applicationsin suspension FCSs of the modelling studies are thatthe induction time of ice fouling is correlated with thedegree of supercooling in the cooling wall, and this canbe used to estimate the critical time interval between twoscraping actions in the SSHE in order to optimize theprocess and save energy.Botsaris and Qian (1999) replaced the SSHE by one

with ultrasonic radiation for ice nucleation. The use ofultrasound permits nucleation at low levels of

supercooling (0.40.5 C) and consequently an inexpen-sive plain heat exchanger can be used for minimizing ice

scaling in the heat exchanger, higher coolant tempera-

tures lead to savings of capital and operation costs of

refrigeration. Moreover, better quality crystals are

obtained due to the use of lower supercooling, and forthis reason the use of ultrasound in scraped surface

exchangers should be considered, as suggested in the

work of Zheng and Sun (2006). Also worth noting is

the work of Verschuur et al. (2002) who replaced the

SSHE with a vacuum crystallization system which oper-

ated below the triple point pressure of an aqueous mix-

ture (

FILM FREEZE CONCENTRATION

A wide variety of liquid foods have been studied infilm freeze concentration. In the case of juices, the max-imum concentrations attained are around 30 Bx andwith sugar solutions 54 Bx. There are no references inthe papers examined in the use of this sort of equipmentin the food industry. There are two film freeze concen-tration techniques that have been studied in the papersexamined: Layer freeze concentration and progressivefreeze concentration. The difference between these twotechniques lies in the equipment used for the formationof ice layers.Progressive freeze concentration involves the crystal-

lization at the bottom or sides of a vessel or in a pipe.In film FCSs the crystallization occurs on a plate.

Layer Freeze Concentration

In layer freeze concentration, the solution to be con-centrated is in contact with a cold surface which consistsof a cooled vertical plate on which the fluid descends; iceforms a single layer on the cold surface and the solutionis concentrated continuously throughout the whole pro-cedure. Muller and Sekoulov (1992) suggested that thelayer freezing process is easier to manage, but when thecrystal grows on a cooled surface this induces a rapidrate of crystallization and under these conditions impureice crystals can be produced. In spite of this moderate icepurity, the disadvantages are compensated by the sim-plicity of the operation, because there are no movingparts in the equipment and no slurry handling.Flesland (1995) has been studying the layer crystalli-

zation in laminar falling film (50

Table 4. Studies that include film freeze concentration and other techniques with sugars solutions.


Mixture of water andsucrose(Flesland, 1995)

To study layer crystallization in afalling film of aqueous solutions.

Cooled plate and glassvessel.

Ice removed in each experiment is less than 0.2 (kg)It is difficult to separate pure ice in a step process for

concentrations from 20% to 40%.Glucose solutions,

glucose, andblue dextransolutions (Liuet al., 1997)

To investigate the effect of themoving speed of the freezingfront, the stirring speed at the icesolution interface and kind ofsolute in freeze concentrationratio.

Progressive freezeconcentrator(cylindrical samplevessel of stainlesssteel).

A lower moving speed and a higher stirring speedproduced a better freeze concentration ratio.

The kind of solute affects the concentration ratio.

Glucose solutions(Liu et al., 1998)

To avoid solution accumulation inthe solid phase.

Progressive freezeconcentrator(bottom plate with alarge number ofholes).

The plate with holes turned out to be an effectivemechanism to avoid subcooling.

Use of the plate allowed a 54% purer solid phase tobe obtained.

Sucrose solutions(Chen et al.,1998)

To study solute inclusion levels inice layers formed on a smoothstainless steel plate undersubcooled flow conditions.

Test section with twofluid channels sepa-rated by a 1(mm)thick stainless steelplate.

Distribution of solid inclusion of ice layer for 20wt%sucrose solution: solute inclusion values along thehorizontal directions are approximately the same(width 14 cm)

Aqueous solutionsof: L-phenyl andsucrose(Matsuda et al.,1999)

Freeze concentration of threeaqueous solutions with/withoutsupersonic radiation under aconstant freezing rate(40mm/h).

Stainless steel freezingcolumn.

Stainless steel bottomplate.

Freezing without supersonic radiation could greatlyconcentrate solutes and decreased the averagedistribution factor under 0.4.

The solutes of large molecular weight are more easilyseparated and concentrated than those of smallmolecular weight.

Sucrose solution(Chen et al.,1999)

To investigate effect of potatostarch particles on sucroseinclusion in ice and effect ofsolute (sucrose) on starchparticle inclusion in ice.

Experimental appara-tus (two fluidchannels).

Sucrose in ice layer formed from sucrose solution isnot affected by the addition of potato starch andpotato starch in ice layer formed from suspensionis influenced by sucrose concentration quitesignificantly.

Glucose solutions(Wakisakaet al., 2001)

To examine ice productivity and theeffect of operating on icecrystallization.

Ice maker unit forfreezing wastewater.

Ice production: 578.6 kg/m2 h99% of glucose was rejected during ice growth with

ice seeding.A higher purity of the ice layer was found at a flow

velocity of 1m/s, with initial solution concentrationfrom 2600 to 5800V of glucose.

Sucrose solutionsand three-com-ponent solution(Kawasaki et al.,2006)

To examine the performance offreeze concentration at constantfreezing rate (40mm/ h) with orwithout ultrasonic irradiation.

Referring to Miyawakisapparatus.

The solutes of smaller molecular weight were sepa-rated and concentrated more effectively thansolutes of larger molecular weight.

The concentration efficiency increased with increasingintensity of ultrasonic irradiation.

Glucose, fructose,and sucrosesolutions(Raventos et al.,2007)

To examine the concentration ofaqueous solutions of glucose,fructose and sucrose using amulti-plate cryoconcentrator.

Pilot plant: (multi-platecryoconcentrator).

Maximum concentration was attained with sucrose,taking the shortest process time (32.2 Bx in16.6 h).

The concentration limits attained with glucose andfructose were similar and it increases linearly overthe process time.

As the solution becomes more concentrated, theamount of water removed in the form of ice grad-ually increases.

Sugar solution(Qin et al., 2006)

To measure the heat transfer coef-ficient and power consumptionof a laboratory scraped-surfaceheat exchanger.

Cylindrical vessel. Heat transfer coefficient was found having a step-function jump at the onset time of phase change.

Glucosewater andsucrosewater(Chudotvortsevand Yatsenko,2007)

To determine the concentrationand temperature of eutecticpoints in aqueous systems withglucose and sucrose.

Cylindrical plasticvessel in a freezer.

An anomalous behavior near the eutectic point wasobserved in the sucrose water system: solutionswith concentrations of 5562% behave identicallyboth in fractional melting of ice and in cooling of asolution until the onset of crystallization.

The component distribution in the sucrosewatersystem at other concentrations is similar to that forthe rest of the systems studied.


The results of the studies show that the performance offreeze concentration is strongly influenced by the type ofcompound present in the solution. Liu et al. (1999) andHalde (1979) found that small solutes are retained in theice more easily than the larger ones. Moreover Kawasakiet al. (2006) noted that the solutes of small molecularweight were separated and concentrated more effectivelythan solutes of larger molecular weight, and this corre-sponded well to the magnitude of the diffusion coeffi-cient of each solute.On the subject of rate of growth of the ice, Liu et al.

(1997) found that a slower rate, on the order of 0.5 cm/hgave lower values for the distribution coefficientbetween the ice and liquid phase K (00.1) in solutionsof sucrose. Likewise, Ramos et al. (2005), using similarequipment to that described by Liu et al. (1997)obtained lower purity in the solid phase with an increasein the rate of growth of ice.Vigorous agitation of the ice-solution interface pre-

vents the retention of solutes in the ice due to the elim-ination of the concentration and temperature gradienton the interface. Halde (1979) found that a faster rate ofagitation in the interface resulted in a greater purity ofthe ice formed with aqueous solutions of glucose. This issimilar to the results obtained by Liu et al. (1997) withsolutions of glucose, where a faster rate of agitation inthe interface (1400 rpm) gave lower values for the

distribution coefficient K (00.1) and by Liu et al.(1999) with tomato juice, which showed that a fasterrate of agitation gave lower concentrations of solids inthe ice phase, with the corresponding increase of con-centration in the solution. Matsuda et al. (1999) inves-tigated the effects of supersonic radiation on theefficiency (distribution coefficient) of separation andconcentration of glucose solutions under various freez-ing rates. They found that for equal mass concentration,efficiency was greatly improved using supersonic radia-tion because of the effect of turbulence in the liquidphase by supersonic cavitation. The most recent researchby Kawasaki et al. (2006) concluded that concentrationefficiency improved with increasing intensity of super-sonic irradiation (Table 4).With the aim of reducing the likelihood of dendritic

growth from the outset of the formation of the solidphase, Liu et al. (1998) proposed a plate with smallholes at the bottom of the receptacle for a faster nuclea-tion of the solution trapped in the holes (Table 4). Theresult obtained was that in the freeze concentration of a5% solution of glucose, use of the plate with holes madeit possible to obtain ice with a glucose retention of 57%lower than in the ice obtained without use of the plate.Regarding the effect of progressive freeze concentra-

tion on the characteristics of the fruit juices, Liu et al.(1999) showed that freeze concentrated and reconsti-tuted tomato juice showed no material difference inacidity, vitamin C content or color in comparison withnon concentrated tomato juice. An examination of theeffect of progressive freeze concentration on the reten-tion of compounds in the flavor of raspberry (Rubusglaucus) pulp revealed a 20% loss of volatiles duringthe freeze concentration process (Ramos et al., 2005;Table 5). The sensory analysis, performed by a panelof trained tasters, found that untreated pulp, enzyme-clarified pulp and freeze concentrated and reconstitutedpulp did not show any material difference in appear-ance, color, taste, aroma, or overall quality.

Tubular Progressive Freeze Concentration

To increase the productivity of progressive freeze con-centration, a tube ice system was proposed by Shiraiet al. (1999). In this method, ice crystal grows on theinside surface of a pipe cooled by a coolant. In thiswork, an ice tube was produced in a bubble-flow circu-lator and the effect of seed ice crystals on tube ice for-mation with a high purity was investigated. Withoutseed ice crystals, substantial supercooling occurs anddendritic ice crystals are formed, the solutes are trappedbetween dendritic ice crystals, thus resulting in poorquality. Use of seed ice crystals is effective because itgenerates other ice crystals, resulting in no supercooling.The productivity was easily increased simply by increas-ing the surface area of the cooling plate. Numbers of

Stirrer

Stainless tube

Unfrozenfraction

Power supply

Frozenfraction

Cooling bath

Hot wire

Motor

Figure 4. Apparatus for progressive freeze concen-tration (Miyawaki et al., 1998).


pipes can be bundled together and interconnected toincrease the cooling surface area.A tubular ice systemwith a large cooling surface area is

an effective method for freeze concentration of tomatojuice and sucrose solutions; increased productivity andhigh yield (Miyawaki et al., 2005; Table 5) showed that.The system comprises two connected sleeved tubes, the

solution circulates inside the tube while the coolant cir-culates outside (Figure 5). The solid phase is generated onthe inner walls of the tubes and the concentrated solutionis re-circulated, it flows through the annulus that has notyet frozen. In this system the slower growth rate of ice andthe higher circulation rate gave a lower effective partitionconstant (distribution coefficient).

Table 5. Studies that include film freeze concentration and other techniques with juices.

Fluid, author and yearof publication Aim of study Equipment Results

Apple juice (Nazir andFarid, 2008)

To estimate the erosion rate atdifferent operating conditionswith an empirical model basedon an analogy between ero-sion and heat-transferphenomenon.

4 and 5mm equilateralcylindrical particlesmade of stainless steel(SS304) fluidized in theinside pipe of a verticaldouble pipe heatexchanger.

It is possible to carry out freezeconcentration of fruit juices in fluidized-bed heat exchanger.

The erosion model predicts stableoperating limits for the fluidized bedat different bed porosities, particlesizes, and concentrations ofapple juice.

Andes berry pulp(Rubus glaucusBenth) (Ramos etal., 2005)

To apply progressive freeze con-centration to Andes berry(Rubus glaucus Benth) pulp tostudy its effects on free vola-tiles composition andconcentration.

Progressive freeze con-centrator (Halde, 1979;Liu et al., 1998).

The color of Andes berry (Rubus glaucusBenth) pulp is preserved during theconcentration process.

This treatment does not change the flavorcompounds and even intensifies aroma.

Tomato juice, sucrosesolution, coffeeextract (Miyawaki etal., 2005)

To apply a tubular ice system toconcentrate liquid food. Toexplore the concentration limitby this method.

Tubular ice system (twostraight pipes).

Tubular ice system gave extremely highconcentrations with good yields.

Sugarcane juice (Raneand Jabade, 2005)

To propose a heat pump-basedfreeze concentration system(FCS) to concentrate sugar-cane juice from 20 to 40 Bx.

Heat pump-based FCS(uses layer freezingprocess).

Use of heat pump facilitates rejection of amajor part of the condenser heat atabout 10 C while melting the ice.

Bagasse saving of 1338 kg per day or for1000 kg jaggery can be achieved.

Tomato juice (Liu et al.,1999)

To apply progressive freeze con-centration to tomato juice andevaluate its effect on juicequality.

Progressive freezeconcentrator.

No substantial differences in acidity, vitaminC content, and color quality after recon-stitution of freeze-concentrated tomatojuice compared with unconcentratedjuice.

Kiwifruit juice (Maltiniand Mastrocola,1999)

To propose the use of freezeconcentration to produce aconcentrated juice to bestored in the frozen state readyfor use by simple addition ofwater.

Separation solidliquid(ice-concentrated solu-tion) by means ofcentrifugation.

The quality of the re-constituted juice isideal.

Slight fading of the green color of the frozenjuice is observed after storage for 90days.

Actinidia (kiwi) juice(Maltini et al., 1998)

To propose the use of freezeconcentration to produce aconcentrated juice to bestored in the frozen state readyfor use by simple addition ofwater.

Separation solidliquid(ice-concentrated solu-tion) by means ofcentrifugation.

The concentrated juice shows aslightly non-Newtonian (pseudo plastic)behavior.

It is not necessary to surpass a content of30% solids in the cryoconcentrationphase to prepare juice of sugary kiwi.

The quality of the reconstituted juice is idealafter 4 months storage at 18 C.

Carrot juice(Mahmutogluand Esin, 1996)

A phase distribution coefficientfor the concentration of liquidfoods at the solidliquid inter-face is defined and estimatedfor freezing of carrot juice.

Cylindrical container (insu-lated with polystyrenefoam).

At four freezing temperatures:range6.5 C to 14.2 C, the distri-bution coefficient was found to be prac-tically independent of the freezingtemperature and is about 0.38.

Apple juice(Olowofoyekuet al., 1980)

Freeze concentration of applejuice using a new rotationalfreeze concentrator.

Rotational freezeconcentrator.

The higher initial feed stream concentrationresulted in higher occluded solids in theice melt.

The difference in temperature effects at10 C and 20 C was not significant.


ASPECTS TO CONSIDER IN THEFUTURE DEVELOPMENT OFFREEZE CONCENTRATION

The future development of freeze concentration willbe centered on overcoming its drawbacks, for thatreason, it might involve the following points:

(a) Suspension crystallization attains levels of icepurity that are clearly superior to those attainedwith film crystallization. For this reason, thefuture of film crystallization technology willdepend on the reduction of levels of occlusion inthe solid phase.

(b) The degree of concentration obtained with film crys-tallization is still lower than that obtained with thesuspension system; an increase in final concentrationwill need to be attained.

(c) Reduction of the level of ice impurity and anincrease in the degree of concentration of the fluidwith the film crystallization system requires progressin the following aspects: Transport of the fluid to be concentrated in a hydra-

ulic regime with the greatest possible turbulence(on a plate, Re> 2500 is recommended, and insidecircular conduits Miyawaki et al. (2005) recom-mends working with velocities of over 1m/s).

Application of the characteristic techniques of meltcrystallization: Controlled seeding, nucleationmechanically induced by shock waves, ultrasonicvibration, supersonic radiation or partial melting(sweating) to drain impurities trapped in the ice.

(d) One advantage of the film crystallization system isits simplicity, in terms of both the construction andoperation of its equipment, nevertheless, in order tooptimize operation, a continuous operation systemwill have to be devised.

(e) The design of equipment with the minimum numberof moving parts in the suspension crystallizationsystem would simplify its operation and it wouldmake it more competitive.

FINAL REMARKS

Although industrial equipment exists for suspensionfreeze concentration, a layer system will be used in thefuture if its results can be improved in terms of ice purityand degree of fluid concentration.Film crystallization technology may be an emerging

technology with the potential to overcome the obstaclesof its industrial feasibility due to the simplicity of thissystem in terms of the construction and operation of itsequipment.

ACKNOWLEDGMENTS

The author J. Sanchez thanks the Ministry of PopularPower for Science and Technology for the fellowshipgranted through FONACIT (National Fund forScience and Technology) from Bolivarian Republic ofVenezuela. The author Y. Ruiz thanks Instituto parael Avance de la Ciencia y Tecnologa COLCIENCIAS for its condonable loan for doctoralstudies, national 2004.

REFERENCES

Ayel V., Lottin O., Faucheux M., Sallier D. and Peerhossaini M.(2006). Crystallization of undercooled aqueous solutions: exper-imental study of free dendritic growth in cylindrical geometry.International Journal of Heat and Mass Transfer 49: 18761884.

Bayindirli L., Ozilgen M. and Ungan S. (1993). Mathematical analysisof freeze concentration of apple juice. Journal of FoodEngineering 19: 95107.

Botsaris G. and Qian R. (1999). Process and system for freeze concen-tration using ultrasonic nucleation useful in effluent processing.United States Patent, Number: 5.966.966, October 19.

Braddock R.J. and Marcy J.E. (1985). Freeze concentration of pine-apple juice. Journal of Food Science 50: 16361639.

Braddock R.J. and Marcy J.E. (1987). Quality of freeze concentratedorange juice. Journal of Food Science 52: 159162.

Ice crystal

Coolant

Pump

Figure 5. Tubular ice system for scale-up of progres-sive freeze concentration (Miyawaki et al., 2005).


Burton J.A., Prim R. and Slichter W.P. (1953). The distribution ofsolute in crystals grown from the melt. The Journal of ChemicalPhysics 21: 19871996.

Caretta O., Courtot F. and Davies T. (2006). Measurement ofsalt entrapment during the directional solidification of brineunder forced mass convection. Journal of Crystal Growth 294:151155.

Chen P., Chen X.D. and Free K.W. (1998). Solute inclusion in iceformed from sucrose solutions on a sub-cooled surface - anexperimental study. Journal of Food Engineering 38: 113.

Chen P., Chen X.D. and Free K.W. (1999). An experimental study onthe spatial uniformity of solute inclusion in ice formed from fall-ing film flows on a sub-cooled surface. Journal of FoodEngineering 39: 101105.

Chen P. and Chen X.D. (2000). A generalized correlation of soluteinclusion in ice formed from aqueous solutions and food liquidson sub-cooled surface. The Canadian Journal of ChemicalEngineering 78: 312319.

Cheftel J.C., Levy J. and Dumay E. (2000). Pressure-assisted freezingand thawing: principles and potentials applications. Food ReviewsInternational 16: 453483.

Chiampo F. and Conti R. (2002). Crioconcentrazione di succhi difrutta in un impianto pilota. Industrie delle Bevande 31: 550554.

Chudotvortsev I.G. and Yatsenko O.B. (2007). Concentration andtemperature of eutectic points in glucose-water and saccharose-water systems, determined by the method of fractional melting ofice. Russian Journal of Applied Chemistry 80: 201205.

Drewett E.M. and Hartel R.W. (2007). Ice crystallization in a scrapedsurface freezer. Journal of Food Engineering 78: 10601066.

Deshpande S.S., Sathe S.K. and Salunkhe D.K. (1984).Freeze concentration of fruit Juices. Food Science and Nutrition20: 173248.

Flesland O. (1995). Freeze concentration by layer crystallization.Drying Technology 13: 17131739.

Gu X., Suzuki T. and Miyawaki O. (2005). Limiting partition coeffi-cient in progressive freeze-concentration. Journal of Food Science70: 546551.

Habib B. and Farid M. (2006). Heat transfer and operating conditionsfor freeze concentration in a liquidsolid fluidized bed heatexchanger. Chemical Engineering and Processing 45: 698710.

Halde R. (1979). Concentration of impurities by progressive freezing.Water Research 14: 575580.

Hartel R.W. (1992). Evaporation and freeze concentration.In: Heldman D.R. and Lund D.B. (eds), Handbook of FoodEngineering. 2nd edn, New York: Marcel Dekker, pp. 341392.

Hartel R.W. and Espinel L.A. (1993). Freeze concentration of skimmilk. Journal of Food Engineering 20: 101120.

Hernandez E., Raventos M., Auleda J.M. and Ibarz A. (2009).Concentration of apple and pear juices in a multi-plate freezeconcentrator. Innovative Food Science and EmergingTechnologies 10: 348355.

Hindmarsh J.P., Russell A.B. and Chen X.D. (2005). Measuring den-dritic growth in undercooled sucrose solution droplets. Journal ofCrystal Growth 285: 236248.

Huige N.J.J. and Thijssen H.A.C. (1972). Production of large crystalsby continuous ripening in a stirred tank. Journal of CrystalGrowth 13: 483487.

Jansen H., Hernandez M.A. and Martnez A. (2001). Concentracionpor congelacion de disoluciones acuosas: un nuevo metodo paraobtener productos innovadores de alta calidad. CTCAlimentacion 10: 1315.

Kawasaki K., Matsuda A. and Kadota H. (2006). Freeze concentra-tion of equal molarity solutions with ultrasonic irradiation underconstant freezing rate: effect of solute. Chemical EngineeringResearch and Design 84: 107112.

Kobayashi A., Shirai Y., Nakanishi K. and Matsuno R. (1996). Amethod for making large agglomerated ice crystals for freezeconcentration. Journal of Food Engineering 27: 115.

Kramer A., Wani K. and Sulli J.H. (1971). Freeze concentration bydirectional freezing. Journal of Food Science 36: 320322.

Lee Y.C. and Lee S.W. (1998). Quality changes during storage inKorean cloudy pear juice concentrated by different methods.Food Sciences and Biotechnology 7: 127130.

Lemmer S., Klomp R., Ruemekorf R. and Scholz R. (2001).Preconcentration of wastewater through the Niro freeze concen-tration process. Chemical Engineering and Technology 24:485488.

Liu L., Miyawaki O. and Nakamura K. (1997). Progressive freeze-concentration of model liquid food. Food Science TechnologyInternational 3: 348352.

Liu L., Tomoyuki F., Hayakawa K. and Miyawaki O. (1998). Preven-tion of initial supercooling in progressive freeze-concentration.Bioscience, Biotechnology, and Biochemistry 62: 24672469.

Liu L., Miyawaki O. and Hayakawa K. (1999). Progressive freeze-concentration of tomato juice. Food Science and TechnologyResearch 5: 108112.

Mahmutoglu T. and Esin A. (1996). Distribution coefficients at theinterface for carrot juice at slow freezing rates. Journal of FoodEngineering 27: 291295.

Maltini E., Mastrocola D., Pittia P., Dalla Rosa M. and Tonizzo A.(1998). Preparazione e conservazione di succo crioconcentrato diactinidia. Rivista di Frutticoltura 10: 5356.

Maltini E. and Mastrocola D. (1999). Preparazione di succo integralecrioconcentrato di kiwifruit. Industrie delle Bevande 28: 69.

Matsuda A., Kawasaki K. and Kadota H. (1999). Freeze concentra-tion with supersonic radiation under constant freezing rate -effect of kind and concentration of solutes. Journal of ChemicalEngineering 32: 569572.

Miyawaki O., Liu L. and Nakamura K. (1998). Effective partitionconstant of solute between ice and liquid phases in progressivefreeze-concentration. Journal of Food Science 63: 756758.

Miyawaki O., Liu L., Shirai Y., Sakashita S. and Kagitani K. (2005).Tubular ice system for scale-up of progressive freeze-concentration. Journal of Food Engineering 69: 107113.

Miyawaki O. (2001). Analysis and control of ice crystal structure infrozen food and their application to food processing. FoodScience and Technology Research 7: 17.

Morison K.R. and Hartel R.W. (2006). Evaporation and freezeconcentration. In: Heldman D.R. and Lund D.B. (eds),Handbook of Food Engineering. 2nd edn, Boca Raton: CRCPress, pp. 496550.

Muller M. and Sekoulov I. (1992). Waste water reuse by freeze con-centration with a falling film reactor. Water Science andTechnology 26: 14751482.

Nazir M. and Farid M.M. (2008). Modeling ice removal in fluidized-bed freeze concentration of apple juice. AIChE Journal 54:29993006.

Nonthanum P. and Tansakul A. (2008). Freeze concentration of limejuice. Maejo International Journal on Science and Technology 1:2737.

Norton T., Delgado A., Hogan E., Grace P. and Da-Wen S. (2009).Simulation of high pressure freezing processes by enthalpymethod. Journal of Food Engineering 91: 260268.

Okawa S., Ito T. and Saito A. (2009). Effect of crystal orientation onfreeze concentration of solutions. International Journal ofRefrigeration 32: 246252.

Olowofoyeku A.K., Gil D. and Kramer A. (1980). Freeze concentra-tion of apple juice by rotational unidirectional cooling.International Journal of Refrigeration 3: 9397.

Omran A.M. and King C.J. (1974). Kinetics of ice crystallization insugar solutions and fruit juices. AIChE Journal 20: 795803.

Otero L. and Sanz P.D. (2000). High pressure shift freezing. Part 1.Amount of ice instantaneously formed in the process.Biotechnology Progress 16: 10301036.

Otero L. and Sanz P.D. (2006). High pressure shift: main factorsimplied in the phase transition time. Journal of FoodEngineering 72: 354363.

Ozum B. and Kirwan D.J. (1976). Impurities in ice crystals grownfrom stierred solutions. Analysis and design of crystallizationprocesses. AIChE Symposium Series 153: 16.


Pardo J.M., Suess F. and Niranjan K. (2002). An investigation into therelationship between freezing rate and mean ice crystal size forcoffee extracts. Trans IchemE 80: 176182.

Patil A.G. (1993). Freeze concentration: an attractive alternative.International Sugar Journal 95: 349355.

Pronk P., Infante C.A. and Witkamp G.J. (2002). Effects of long-termice slurry storage on crystal size distribution. In: Melinder A.(ed.), Proceedings of 5th Workshop on Ice Slurries of the IIR.Stockholm, pp. 151160, 3031 May.

Pronk P., Infante C.A. and Witkamp G.J. (2005). A dynamic model ofOstwald ripening in ice suspensions. Journal of Crystal Growth275: 355361.

Qin F., Che X.D., Ramachandra S. and Free K. (2006). Heat transferand power consumption in a scraped-surface heat exchangerwhile freezing aqueous solutions. Separation and PurificationTechnology 48: 150158.

Qin F.G.F., Chen X.D. and Free K. (2009). Freezing on subcooledsurfaces, phenomena, modeling and applications. InternationalJournal of Heat and Mass Transfer 52: 12451253.

Rahman M.S., Ahmed A. and Chen X.D. (2006). Freezing-meltingprocess and desalination: I. review of the state-of-the-art.Separation and Purification Reviews 35: 5996.

Ramos F.A., Delgado J.L., Bautista E., Morales A.L. and Duque C.(2005). Changes in volatiles with the application of progressivefreeze-concentration to Andes berry (Rubus glaucus Benth).Journal of Food Engineering 69: 291297.

Ramteke R.S., Singh N.I., Rekha M.N. and Eipeson W.E. (1993).Methods for concentration of fruit juices: A critical evaluation.Journal of Food Science and Technology 30: 391402.

Rane M.V. and Jabade S.K. (2005). Freeze concentration of sugarcanejuice in a jiggery making process. Applied Thermal Engineering25: 21222137.

Raventos M., Hernandez A., Auleda J. and Ibarz A. (2007).Concentration of aqueous sugar solutions in a multi-plate cryo-concentrator. Journal of Food Engineering 79: 577585.

Rutter J.W. and Chalmers B. (1953). A prismatic structure formedduring solidification metals. Canadian Journal of Physics 31:1539.

Scholz R., Ruemekorf R., Verdoes D. and Nienoord M. (2002).Wash columns state of the art and further developments.In: Chianese A. (ed.), Proceedings of 15th InternationalSymposium on Industrial Crystallization, Chemical EngineeringTransactions, Vol. I, AIDIC Servizi S.r.l, Sorrento, Italy,pp. 14251430.

Schwartzberg H.G. (1990). Food freeze concentration.In: Schwartzberg H.G. and Rao M.A. (eds), Biotechnology andFood Process Engineering. New York: Marcel Dekker,pp. 127202.

Shirai Y., Sugimoto T., Hasnimoto M., Nakanishi K. and Matsuno R.(1987). Mechanism of ice growth in a batch crystallizer with anexternal cooler for freeze concentration. Agricultural andBiological Chemistry 51: 23592366.

Shirai Y., Wakisaka M., Miyawaki O. and Sakashita S. (1999). Effectof seed on formation of tube ice whit high purity for a freezewastewater treatment system with a bubble-flow circulator.Water Research 33: 13251329.

Stamatiou E., Meewisse J.W. and Kawaji M. (2005). Ice slurry gener-ation involving moving parts. International Journal ofRefrigeration 28: 6072.

Stocking H.J. and King C.J. (1976). Secondary nucleation of ice sugarsolutions and fruit juices. AIChE Journal 22: 131140.

Teraoka Y., Saito A. and Okawa S. (2002). Ice crystal growth insupercooled solution. International Journal of Refrigeration 25:218225.

Thijssen H.A.C. (1975). Current developments in the freeze concen-tration of liquid foods. In: Goldblith S.A., Rey L. and RothmayrW.W. (eds), Freeze Drying and Advanced Food Technology.London: Academic Press, p. 481.

Thijssen H.A.C. (1986). The economics and potentials of freeze con-centration for fruit juices. In: International Federation of FruitJuice Producers, XIX Scientific Technical Commission,Symposium Den Haag, pp. 97103.

Van Nistelrooij M. (2005). Bridging the cost barrier to freeze concen-tration. Food and Beverage Asia, April/May.

Van Weelden. (1994). Freeze concentration: the alternative for singlestrength juices. Fruit Processing 4: 140143.

Verdoes D., Arkenbout G.J., Bruinsma O.S.L., Koutsoukos P.G. andUlrich J. (1997). Improved procedures for separating crystalsfrom the melt. Applied Thermal Engineering 17: 879888.

Verschuur R.J., Scholz R., Van Nistelrooj M. and Scheurs B. (2002).Innovations in freeze concentration technology. 15th InternationalSymposium on Industrial Crystallization. Sorrento, Italy, September.

Wakisaka M., Shirai Y. and Sakashita S. (2001). Ice crystallization ina pilot-scale freeze wastewater treatment system. ChemicalEngineering and Processing 40: 201208.

Zheng L. and Sun D. (2006). Innovative applications of power ultra-sound during food freezing processes a review. Trends in FoodScience & Technology 17: 1623.


freeze concentration review

Documents

univ estdl

ponta grossa

technology http

freeze concentrationtechnique

agrifood engineering

higher levels of concentration

suitable technology

technology internationalj