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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
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
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