Stephanie Clark, Ph.D.Stephanie Clark, Ph.D.Iowa State UniversityIowa State University

Department of Food Science and Human NutritionDepartment of Food Science and Human Nutrition

ContentsContents

�� Cheesemaking terminologyCheesemaking terminology

�� Chemistry and microbiology of cheese milkChemistry and microbiology of cheese milk

�� Steps in cheesemakingSteps in cheesemaking

�� Sheep milk chemistrySheep milk chemistry

�� Cheesemaking with sheep milkCheesemaking with sheep milk

�� QuestionsQuestions

Cheesemaking terminologyCheesemaking terminology

�� AshAsh

�� Culture/starter cultureCulture/starter culture

�� ChymosinChymosin

�� CaseinCasein

�� WheyWhey

�� TATA

�� pHpH

Culture/starter cultureCulture/starter culture

�� Starter cultures Starter cultures are lactic acid bacteria that are lactic acid bacteria that

�� ““startstart”” the fermentationthe fermentation

�� convert lactose to lactic acid and other productsconvert lactose to lactic acid and other products

�� contribute to flavor, body and texture of cheesecontribute to flavor, body and texture of cheese

�� MesophilesMesophiles

�� ““likelike”” middle temperatures (68middle temperatures (68--111111°°F)F)

�� used for Cheddar, Jack, Cottage, Gouda and Blueused for Cheddar, Jack, Cottage, Gouda and Blue

�� ThermophilesThermophiles

�� ““likelike”” high temperatures (111high temperatures (111--140140°°F)F)

�� used for Italian style cheesesused for Italian style cheeses

Culture/starter cultureCulture/starter culture

�� Adjunct culturesAdjunct cultures

�� are added intentionally to cheese milkare added intentionally to cheese milk

�� work later in the processwork later in the process

�� contribute to flavor, body and texture of cheesecontribute to flavor, body and texture of cheese

�� Adventitious bacteria Adventitious bacteria (nonstarter lactic acid (nonstarter lactic acid bacteria)bacteria)

�� enter the cheesemaking process at various points and enter the cheesemaking process at various points and contribute to (positively or negatively) cheese qualitycontribute to (positively or negatively) cheese quality

Cheesemaking terminologyCheesemaking terminology

�� Titratable acidity (TA)Titratable acidity (TA) measures the measures the AMOUNT AMOUNT of of acid in a volumeacid in a volume

�� A base (NaOH) is used to titrate to an end point (pink A base (NaOH) is used to titrate to an end point (pink color change)color change)

�� Apparent acidity measures fresh milk citrates, Apparent acidity measures fresh milk citrates, phosphates, proteinsphosphates, proteins

�� Developed acidity measures lactic acid (fermentation)Developed acidity measures lactic acid (fermentation)

�� pHpH measures the measures the CONCENTRATION CONCENTRATION of hydrogen of hydrogen ions (H+) in a solutionions (H+) in a solution

�� Acid/acidic conditions are below 7Acid/acidic conditions are below 7

�� 7 = neutral7 = neutral

�� Base/basic conditions are above 7Base/basic conditions are above 7

Milk proteinsMilk proteins

Kappa-casein

Caseins Whey Proteins

αs1-caseinαs2-caseinβ-casein

Make up ~ 80% of protein About 20% of milk protein

Sensitive to acid/stable to heat Sensitive to heat/stable to acid

β−lactoglobulinα−lactalbumin

Other more minor ones

“sensitive” to Ca++

stable to Ca++

During cheesemaking >>>>> Whey

High quality cheese makingHigh quality cheese making

�� Begins with high quality milkBegins with high quality milk�� From healthy animalsFrom healthy animals

�� No inhibitory substances (antibiotics)No inhibitory substances (antibiotics)

�� Cooled to less than 45Cooled to less than 45°°F (7F (7°°C) within 2 h of collectionC) within 2 h of collection

�� Fresh (stored < 48 h)Fresh (stored < 48 h)

�� Low bacteria levels Low bacteria levels

�� Normal somatic cell counts Normal somatic cell counts

�� Stainless steel equipment, pipes and fittingsStainless steel equipment, pipes and fittings

�� Heat treatment??Heat treatment??

Heat treatment of cheese milk?Heat treatment of cheese milk?

�� Raw? Raw?

�� Cheeses will likely have native flavorsCheeses will likely have native flavors

�� Native microflora may include pathogensNative microflora may include pathogens

�� Must be aged a minimum of 60 days at or above 35Must be aged a minimum of 60 days at or above 35°°FF

�� Heat treated?Heat treated?

�� Inactivates some pathogens, enzymes and spoilage Inactivates some pathogens, enzymes and spoilage microorganismsmicroorganisms

�� Treated the same way (legally) as raw milk Treated the same way (legally) as raw milk

Heat treatment of cheese milk?Heat treatment of cheese milk?

�� Pasteurized?Pasteurized?�� Flavors result from starter cultures and adventitious bacteriaFlavors result from starter cultures and adventitious bacteria

�� Not required for aged cheesesNot required for aged cheeses

�� Required by law for sale of fresh cheesesRequired by law for sale of fresh cheeses

�� Note: Do not homogenize cheese milkNote: Do not homogenize cheese milk

KEY POINT: KEY POINT:

Every step of the process, from animal to consumer, Every step of the process, from animal to consumer, influences the safety and quality of the end productinfluences the safety and quality of the end product

High quality cheese makingHigh quality cheese making

�� Requires hygiene and sanitationRequires hygiene and sanitation�� Properly trained employeesProperly trained employees

�� Hair nets and beard netsHair nets and beard nets

�� Clean and sanitized hands (gloves)Clean and sanitized hands (gloves)

�� Foot bathsFoot baths

�� Appropriate chemicals and usageAppropriate chemicals and usage

�� Chlorinated alkaline cleansersChlorinated alkaline cleansers

�� Acid cleansers Acid cleansers

�� Sanitizers (sodium hypochlorite, etc.)Sanitizers (sodium hypochlorite, etc.)

�� Time, temperature, concentration and agitationTime, temperature, concentration and agitation

High quality cheese makingHigh quality cheese making

�� Proceeds with high quality ingredients and suppliesProceeds with high quality ingredients and supplies

�� Starter cultureStarter culture

�� Coagulating enzyme (chymosin)Coagulating enzyme (chymosin)

�� Molds (both microbial and physical)Molds (both microbial and physical)

�� SaltSalt

�� Other inclusions (herbs, fruits, nuts)Other inclusions (herbs, fruits, nuts)

�� Involves good recordInvolves good record--keepingkeeping

�� Keep track of failures along with successesKeep track of failures along with successes

The steps in cheese makingThe steps in cheese making

�� Place high quality milk into recently cleaned Place high quality milk into recently cleaned and sanitized vatand sanitized vat

�� Gradually raise temperature to target for cultureGradually raise temperature to target for culture

�� Gently agitate and add culture Gently agitate and add culture

�� Note time and pH or TANote time and pH or TA

�� Ripen (for recommended time)Ripen (for recommended time)

The steps in cheese makingThe steps in cheese making

WhatWhat’’s happening, s happening, chemically, in the cheese chemically, in the cheese

vat?vat?

Milk Protein ChemistryMilk Protein Chemistry

Casein sub-micelle

Calcium phosphate

Kappa casein

Casein Micelle

αs1-caseinαs2-caseinβ-casein

Milk Protein ChemistryMilk Protein Chemistry

Casein Micelle

Native pH of milk(~6.7)

Lactose Fermentation ChemistryLactose Fermentation Chemistry

pH 4.6

Coagulation ChemistryCoagulation Chemistry

The steps in cheese makingThe steps in cheese making

�� Add coagulating enzyme and stop agitation Add coagulating enzyme and stop agitation

�� Note timeNote time

�� Check curdCheck curd

�� Cut curd (size depends on cheese type)Cut curd (size depends on cheese type)

�� note timenote time

�� Heal (rest recommended time) Heal (rest recommended time)

But cheese makers are But cheese makers are sometimes impatientsometimes impatient……

Lactose Fermentation Lactose Fermentation PLUS PLUS

Coagulating Enzyme ChemistryCoagulating Enzyme Chemistry

pH 6.5Chymosin

Coagulation Enzyme ChemistryCoagulation Enzyme Chemistry

The steps in cheese makingThe steps in cheese making

�� Begin gentle agitation of curd Begin gentle agitation of curd �� Note time and pH/TANote time and pH/TA

�� Heat/cook/stir curd (depends on cheese type)Heat/cook/stir curd (depends on cheese type)

�� Turn off heat at target temperature and agitate until target Turn off heat at target temperature and agitate until target time (note time and pH/TA)time (note time and pH/TA)

The steps in cheese makingThe steps in cheese making

�� Drain wheyDrain whey�� May be incrementalMay be incremental

�� May include wash stepMay include wash step

�� Subsequent steps vary according to cheese typeSubsequent steps vary according to cheese type

Defining steps in cheese Defining steps in cheese makingmaking

�� FetaFeta�� Mold/hoopMold/hoop

�� Salt/brineSalt/brine

�� CottageCottage�� Rinse curds with acidified, chlorinated water 3XRinse curds with acidified, chlorinated water 3X

�� Add cream dressing to curd (about 50:50)Add cream dressing to curd (about 50:50)

Defining steps in cheese Defining steps in cheese makingmaking

�� BlueBlue--veined moldveined mold--ripened varietiesripened varieties�� Inoculate with mold sporesInoculate with mold spores

�� Mold/hoopMold/hoop

�� Aerate with needlesAerate with needles

�� Age in high relative humidity environmentAge in high relative humidity environment

�� CamembertCamembert--style moldstyle mold--ripened varietiesripened varieties�� Mold/hoopMold/hoop

�� Spray surfaces with mold sporesSpray surfaces with mold spores

�� Age in high relative humidity environmentAge in high relative humidity environment

Defining steps in cheese Defining steps in cheese makingmaking

�� Cheddar and Jack typesCheddar and Jack types

�� CheddarCheddar

�� Mill (if cheddared)Mill (if cheddared)

�� SaltSalt

�� Mold/hoopMold/hoop

�� PressPress

�� AgeAge

Defining steps in cheese Defining steps in cheese makingmaking

�� Mozzarella and Provolone stylesMozzarella and Provolone styles

�� StretchStretch

�� BrineBrine

�� PackagePackage�� May include plastic, wax, etc.May include plastic, wax, etc.

�� Age/ripenAge/ripen�� All raw milk cheeses must be aged at least 60 days at All raw milk cheeses must be aged at least 60 days at 3535°°F or greaterF or greater

�� Fresh cheese (pasteurized milk) may be sold right Fresh cheese (pasteurized milk) may be sold right awayaway

The steps in cheese makingThe steps in cheese making

Sheep Milk ChemistrySheep Milk Chemistry

Water (%) Lactose (%) Fat (%) Protein (%) Ash (%)

Cow milk 87.5 4.9 3.6 3.4 0.7

Goat milk 87.0 4.5 4.1 3.6 0.8

Sheep milk 80.9 5.3 7.0 5.9 0.9

Milk chemistry compared among species

Milk Fatty Acid Chemistry of Milk Fatty Acid Chemistry of Species ComparedSpecies Compared

Highertotal fat

Sheep Milk ChemistrySheep Milk Chemistry

�� Compared to cow milk, sheep milk Compared to cow milk, sheep milk

�� Has lower water contentHas lower water content

�� Has higher lactose, fat, protein and ashHas higher lactose, fat, protein and ash

�� Has more overall flavorHas more overall flavor

�� Higher proportion of short chain volatile fatty acidsHigher proportion of short chain volatile fatty acids

�� Yields more cheese per pound of milkYields more cheese per pound of milk

�� Yields less wheyYields less whey

�� Cheese is more whiteCheese is more white

�� BetaBeta--carotene converted to Vitamin Acarotene converted to Vitamin A

Cheese Making Cheese Making with Sheep Milkwith Sheep Milk

�� Just about any cheese made Just about any cheese made out of cow or goat milk can be out of cow or goat milk can be made out of sheep milk.made out of sheep milk.

�� Unique properties of sheep Unique properties of sheep milk will be more pronounced milk will be more pronounced in cheese.in cheese.

Cheese Making Cheese Making with Sheep Milkwith Sheep Milk

�� Always remember the prioritiesAlways remember the priorities�� SanitationSanitation

�� SafetySafety

�� QualityQuality

�� ExperimentExperiment�� Keep recordsKeep records

�� Set yourself apartSet yourself apart

�� Enjoy!Enjoy!

Stephanie Clark, Ph.D.Stephanie Clark, Ph.D.Iowa State UniversityIowa State University

Department of Food Science and Human NutritionDepartment of Food Science and Human Nutrition

milkmade@iastate.edumilkmade@iastate.edu

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Sheep Milk ProductionSheep Milk Production

Rank Breed Average Milk Production, lb.

Milk production relative to E. Friesian

1 East Friesian 658 1.00

2 Lacaune 627 0.95

3 Dorset 409 0.62

Comparative Performance of Breeds for Commercial Milk Production

Unpublished data from the University of Wisconsin-Madison