MilkMilk

TrendsTrendsFluid milk and cream consumption has declined Fluid milk and cream consumption has declined steadily reaching a record low of 200.5 lb in steadily reaching a record low of 200.5 lb in 2005. In 1970, fluid milk and cream 2005. In 1970, fluid milk and cream consumption was 275 lb. There has been a consumption was 275 lb. There has been a trend to less consumption of whole milk trend to less consumption of whole milk products to more consumption of lower fat milk products to more consumption of lower fat milk products. products.

Frozen dairy products, such as ice cream have Frozen dairy products, such as ice cream have been declining since about 1994. been declining since about 1994.

Gross CompositionGross Composition

Component Cow

Water 87.3

Lactose 4.8

Fat 3.7

Protein 3.4

Salts(minerals) 0.7

% by weight

NutrientsNutrients

Milk contains many nutrients: protein, Milk contains many nutrients: protein, lactose, fats, vitamins, minerals, and lactose, fats, vitamins, minerals, and enzymesenzymes

Milk is a complex physiochemical system. Milk is a complex physiochemical system. It has particles in:It has particles in:

1. True solution - sugar and salt1. True solution - sugar and salt

2. Colloidal dispersion - protein2. Colloidal dispersion - protein

3. Globules - fat3. Globules - fat

ProteinProteinCasein - 80% of total milk protein. Casein - 80% of total milk protein. Casein is a phosphoprotein containing Casein is a phosphoprotein containing phosphoric acid. phosphoric acid. – Coagulates to form a gelCoagulates to form a gel– Coagulates at pH 4.6Coagulates at pH 4.6– Coagulates at high pH (6.5) with rennetCoagulates at high pH (6.5) with rennet– Several types of casein - alpha, beta, gamma, Several types of casein - alpha, beta, gamma,

kappakappa

Whey protein – 20% of total milk proteinWhey protein – 20% of total milk protein– Do not coagulate at pH 4.6Do not coagulate at pH 4.6– Do not coagulate with rennetDo not coagulate with rennet

ProteinsProteins

– Lactalbumin - 8% of protein (N) Lactalbumin - 8% of protein (N) Water soluble and forms flucculent Water soluble and forms flucculent precipitate that settles on bottom and sides precipitate that settles on bottom and sides of pan when heated. of pan when heated.

– Lactoglobulin - 3.5% of protein (N) Lactoglobulin - 3.5% of protein (N) Insoluble in water but soluble in dilute Insoluble in water but soluble in dilute neutral salts. Precipitated by heat.neutral salts. Precipitated by heat.

– Serum albumin and immunoglobulinSerum albumin and immunoglobulin

FatFatExists as large globules varying in size from Exists as large globules varying in size from 0.1-10um in diameter.0.1-10um in diameter.

Mostly (>95% triglycerides)Mostly (>95% triglycerides)

Triglycerides = glycerol + fatty acidsTriglycerides = glycerol + fatty acids

Milkfat contains high proportion of short Milkfat contains high proportion of short chain fatty acids (Cchain fatty acids (C44-C-C1010))

Butyric acid (CButyric acid (C44) is unique to milkfat) is unique to milkfat

Responsible for flavors and aroma when Responsible for flavors and aroma when acted by enzyme lipase.acted by enzyme lipase.

Carbohydrate (Lactose)Carbohydrate (Lactose)

Milk contains lactose or milk sugar.Milk contains lactose or milk sugar.Lactose = glucose + galactoseLactose = glucose + galactoseSome people exhibit lactose intolerance Some people exhibit lactose intolerance and thus milk may give cramping and and thus milk may give cramping and diarrheadiarrheaPrinciple source of energy for lactic acid Principle source of energy for lactic acid bacteria.bacteria.Bacteria converts lactose to lactic acid Bacteria converts lactose to lactic acid (cheese, yogurt, cultured milk, sour cream)(cheese, yogurt, cultured milk, sour cream)

VitaminsVitamins

B1 - thiamine B1 - thiamine B2 - riboflavin B2 - riboflavin B6 - pyridoxine B6 - pyridoxine B12 - cyanocobalamin B12 - cyanocobalamin niacin niacin pantothenic acid pantothenic acid Vitamin A, D, E and K (Fat soluble Vitamin A, D, E and K (Fat soluble vitamins)vitamins)

Minerals and EnzymesMinerals and EnzymesCalciumCalcium

PhosphorusPhosphorus

Low in copper and ironLow in copper and iron

Low levels of sodium, chloride, MagnesiumLow levels of sodium, chloride, Magnesium

Plasmin Plasmin

LipaseLipase

Milk is well buffered by protein and salts Milk is well buffered by protein and salts especially phosphatesespecially phosphates

PasteurizationPasteurization

Low temperature holding (LTH) - 63 C or Low temperature holding (LTH) - 63 C or 145 F for 30 min.145 F for 30 min.

High temperature short time (HTST) 72 C High temperature short time (HTST) 72 C or 162 F for 15 sec.or 162 F for 15 sec.

Ultrapasteurization - 138 C or 280 F for Ultrapasteurization - 138 C or 280 F for 2 or more sec. 2 or more sec.

Ultra high temperature (UHT) - 138-150C Ultra high temperature (UHT) - 138-150C or 280-302 F for 2-6 sec. or 280-302 F for 2-6 sec.

HomogenizationHomogenization

HomogenizationHomogenization

Mechanical treatment of the fat globules in Mechanical treatment of the fat globules in milk brought about by passing milk under milk brought about by passing milk under high pressure through a tiny orificehigh pressure through a tiny orifice

Decrease in the average diameter and an Decrease in the average diameter and an increase in number and surface areaincrease in number and surface area

Reduced tendency for creaming of fat Reduced tendency for creaming of fat globulesglobules

Enhanced stability of homogenized milkEnhanced stability of homogenized milk

Types of MilkTypes of MilkFluid Fluid

1. Whole - 3.25% butterfat1. Whole - 3.25% butterfat

2. Low-fat - 2% or 1% butterfat2. Low-fat - 2% or 1% butterfat

3. Skim or nonfat - fat-free 3. Skim or nonfat - fat-free

4. Lactose-free-treated with lactase to form glucose 4. Lactose-free-treated with lactase to form glucose and galactose and galactose

CannedCanned

1. Evaporated - 60% water removed by heat1. Evaporated - 60% water removed by heat

2. Sweetened condensed - sugar added and 1/3 2. Sweetened condensed - sugar added and 1/3 water removedwater removed

Dried Dried

1. Spray dried - 2/3 water removed by 1. Spray dried - 2/3 water removed by

vacuum, them sprayed into chamber of vacuum, them sprayed into chamber of

hot air.hot air.

2. Foam spray dried - spraying a jet of hot 2. Foam spray dried - spraying a jet of hot

air into concentrated skim milk.air into concentrated skim milk.

3. Instant - agglomerated, porous particles 3. Instant - agglomerated, porous particles

take up liquid quickly. take up liquid quickly.

Filled milks - fat other than milkfat, water, NFMS, Filled milks - fat other than milkfat, water, NFMS, emulsifiers, coloring, and flavoring.emulsifiers, coloring, and flavoring.

Imitation - no milk products, contain water, corn syrup Imitation - no milk products, contain water, corn syrup solids, sugar, vegetable fat, protein (Na caseinate or solids, sugar, vegetable fat, protein (Na caseinate or soy protein).soy protein).

CulturedCultured

1. Yogurt - culture of 1. Yogurt - culture of Lactobacillus Lactobacillus

bulgaricusbulgaricus and and StreptococcusStreptococcus

thermophilusthermophilus is used. is used.

2. Buttermilk - 2. Buttermilk - Streptococcus lactisStreptococcus lactis..

3. Acidophilus milks - 3. Acidophilus milks - Lactobacillus Lactobacillus

acidophilusacidophilus, balance bacteria in GI tract., balance bacteria in GI tract.

Other dairy products:Other dairy products:

1. Cheese1. Cheese

2. Butter2. Butter

Milk in Food PreparationMilk in Food Preparation

Effects of Heating Effects of Heating Lactoglobulin and lactalbumin are Lactoglobulin and lactalbumin are denatured by heat. Increased with acid or denatured by heat. Increased with acid or salt. Heat causes the decreased salt. Heat causes the decreased dispersion of calcium phosphate. Film or dispersion of calcium phosphate. Film or skim forms-coagulated protein, skim forms-coagulated protein, precipitated salts, and fat globules. precipitated salts, and fat globules. Browning - caramelization Browning - caramelization and Maillard reactionand Maillard reaction

Effects of Acid Effects of Acid

Cause coagulation of casein. As pH decreases Cause coagulation of casein. As pH decreases from 6.6 to 4.6, colloidally dispersed casein from 6.6 to 4.6, colloidally dispersed casein becomes unstable, adheres and forms curds. becomes unstable, adheres and forms curds. Calcium is lost.Calcium is lost.

Effects of Enzymes Effects of Enzymes

Rennin clots milk, requires 40-42Rennin clots milk, requires 40-42°° C or 104-108 C or 104-108°° F F and slightly acid medium.and slightly acid medium.

Effects of Phenolic Compounds and Tannins cause Effects of Phenolic Compounds and Tannins cause increased curdling with heat.increased curdling with heat.

Effects of Salts Salts Effects of Salts Salts and NaCl in foods may cause coagulation of and NaCl in foods may cause coagulation of proteinsproteins

CreamsCreamsHalf & Half - 10.5 to 18 % creamHalf & Half - 10.5 to 18 % cream

Light or coffee cream - 18 to 30% creamLight or coffee cream - 18 to 30% cream

Light whipping cream - 30 to 36% creamLight whipping cream - 30 to 36% cream

Heavy whipping cream - 36% or more creamHeavy whipping cream - 36% or more cream

Sour cream - Sour cream - Streptococcus lactisStreptococcus lactis

Dried creamDried cream

Nondairy creamer - corn syrup solids, vegetable Nondairy creamer - corn syrup solids, vegetable fat, protein (Na caseinate or soy), emulsifier, saltfat, protein (Na caseinate or soy), emulsifier, salt

Nondairy whipped topping - sugar, vegetable oil Nondairy whipped topping - sugar, vegetable oil (hydrogenated), Na caseinate, emulsifiers(hydrogenated), Na caseinate, emulsifiers

Whipped CreamWhipped Cream

Foam is a dispersion of gas in a liquid. Foam is a dispersion of gas in a liquid. Foaming agent lowers surface tension Foaming agent lowers surface tension allowing liquid to surround gas. Stabilizing allowing liquid to surround gas. Stabilizing agent keeps gas separated. In cream, agent keeps gas separated. In cream, liquid is the water in cream, gas is air liquid is the water in cream, gas is air beaten in, foaming agent is protein where beaten in, foaming agent is protein where film of protein surrounds air bubbles, and film of protein surrounds air bubbles, and fat acts as the stabilizer.fat acts as the stabilizer.

Effects on Whipping CreamEffects on Whipping Cream

Temperature - coldTemperature - cold

Percent of fatPercent of fat

ViscosityViscosity

SugarSugar

Whipped evaporated milk - less fat thus Whipped evaporated milk - less fat thus less stableless stable

Whipped NFDM - less fat thus less stability, Whipped NFDM - less fat thus less stability, more protein thus more foam formation or more protein thus more foam formation or bigger volumebigger volume

CheeseCheese

TrendsTrends

In 2005, Americans consumed 31.4 In 2005, Americans consumed 31.4 pounds of cheese per person, 8 times pounds of cheese per person, 8 times more than they did in 1909 and more than more than they did in 1909 and more than twice as much as they did in 1975twice as much as they did in 1975

More that half (55-65%) of this comes in More that half (55-65%) of this comes in commercially manufactured and prepared commercially manufactured and prepared foods, such as fast food sandwiches and foods, such as fast food sandwiches and packaged snack foodspackaged snack foods

Pasteurized cows’ milk

Starter (1-2%, v/v): 310C

Rennet (1:15,000) (CaCl2, 0.02%, w/v)

. Coagulum

Cut the coagulum ~6mm cubes

Raise temperature : 300C to 37-390 over ~ 30 min

Cook Cook at 37-390C for ~ 1h

Whey drainage

Cheddaring of the curd

Milling of the curd pH ~ 5.2

NaCl, (~ 2%, w/w)

Dry salting

Moulding and pressing

Ripening 0.5- 2 years at 6-80C

Cheddar cheese

Cheese MakingCheese MakingSeparation of protein in milk begins with acid, Separation of protein in milk begins with acid, rennin or both which coagulates casein- forms rennin or both which coagulates casein- forms curdscurds

Acid - added or from souringAcid - added or from souring

Rennin - proteolytic enzymeRennin - proteolytic enzyme

Curds are cut, heated, drained of whey, salted, Curds are cut, heated, drained of whey, salted, formed, ripened by molds or bacteria under formed, ripened by molds or bacteria under temperature and humidity control.temperature and humidity control.

Clear liquid left called whey and contains proteins, Clear liquid left called whey and contains proteins, lactose, water soluble vitamins and some mineralslactose, water soluble vitamins and some minerals

Nutritive ValueNutritive Value

ProteinProtein

FatFat

Vitamin AVitamin A

Minerals (Calcium and Phosphorus)Minerals (Calcium and Phosphorus)

Cheese is high in Na or saltCheese is high in Na or salt

Types of CheeseTypes of CheeseSoft, semihard, hard - moisture contentSoft, semihard, hard - moisture content

Unripened or Ripened - physical and chemical Unripened or Ripened - physical and chemical changes in aroma, flavor, texture, and composition. changes in aroma, flavor, texture, and composition. Sharp or mild. Mold or bacteria ripened.Sharp or mild. Mold or bacteria ripened.

Cold pack - mixing varieties of cheese with added Cold pack - mixing varieties of cheese with added acid, salt, water, coloring and spice.acid, salt, water, coloring and spice.

Processed cheese - blending cheese with heat and Processed cheese - blending cheese with heat and emulsifier.emulsifier.

Processed cheese food and spread - similar to Processed cheese food and spread - similar to processed cheese with less cheese and more milk processed cheese with less cheese and more milk products plus stabilizers.products plus stabilizers.

Cooking CheeseCooking CheeseHard cheese softens, then melts at low Hard cheese softens, then melts at low temperature. More heat leads to separation of temperature. More heat leads to separation of fat and development of tough rubbery curd fat and development of tough rubbery curd which forms strings and hardens on cooling.which forms strings and hardens on cooling.

Well ripened cheese and processed cheese Well ripened cheese and processed cheese blend better in heated mixtures than mild blend better in heated mixtures than mild natural cheeses and are less likely to produce a natural cheeses and are less likely to produce a grainy texture and stringinessgrainy texture and stringiness

Milk sugar causes browning in cheese which is Milk sugar causes browning in cheese which is exposed to dry heat.exposed to dry heat.

SummarySummary

Milk is an essential nutrientMilk is an essential nutrient

Milk can be used in the manufacture of Milk can be used in the manufacture of various dairy productsvarious dairy products

Each product has its own characteristic in Each product has its own characteristic in terms of sensory propertiesterms of sensory properties

Dairy products are used in everyday Dairy products are used in everyday cooking and industrially prepared foodscooking and industrially prepared foods

Power Point AuthorsPower Point Authors

Jon Christiano Jon Christiano

&&

Dr. Jane RossDr. Jane Ross

The University of Vermont

Foods and Nutrition

Basic Concepts of Food