Milk and Milk Products

Milk and Milk Products

Chapter 23

Introductory Foods, 13th ed.Bennion and Scheule

© 2010 Pearson Higher Education,Upper Saddle River, NJ 07458. • All Rights Reserved.2

Consumption Trends Using USDA food disappearance data

Overall milk consumption has declined since 1970

Fat-reduced milk use has increased

Record high levels of cheese



Nutritive Value 2005 Dietary Guidelines for Americans

3 cups of milk recommended daily

Major source of Calcium Complete protein Vitamin D – when fortified Riboflavin Niacin value Other nutrients



Composition of Whole Milk 88 percent water 3.3 percent protein 3.3 percent fat 4.7 percent carbohydrate 0.7 percent ash (minerals)



Protein in Milk Casein

80 percent of milk protein A phosphoprotein Precipitates if

Acidic Rennet added

Whey Lactalbumin and lactoglobulin Coagulated by heat Byproduct of cheese making



Fat Milk is an emulsion

Milk fat droplets are dispersed in the milk serum

Fat in milk called Milk fat Butter fat Cream

Milk fat is composed of Triglycerides – primary type Phospholipids Sterols – cholesterol



Carbohydrate Lactose

A disaccharide If hydrolyzed produces

Glucose Galactose

Least soluble of common sugars

Lactose intolerance Role of enzyme called lactase



Minerals and Vitamins Minerals

Calcium, phosphorus, magnesium, and sodium

Vitamins Fat soluble

A, D, E, K Low-fat milk is fortified with Vitamin A

Water soluble Milk is fortified with Vitamin D



Color White appearance because of

Colloidally dispersed casein micelles Calcium phosphate salts

Yellow pigments Carotenes Riboflavin

Greenish-yellow fluorescent color in liquid whey Riboflavin



Flavor Slightly sweet (lactose)

Heat processing Minimal impact on flavor Tends to disappear on storage

Off-flavors From feed, bacteria, chemical changes, absorption of

foreign flavors Light exposure



pH Fresh milk

pH about 6.6

Acidity increases on standing with loss of carbon dioxide

Acidity increases by action of lactic acid producing bacteria



Sanitation and Grading Grade A Pasteurized Milk Ordinance

Grading Determined by sanitary codes



Bovine Somatotropin rBST Naturally occurring protein hormone

Artificially synthesized via use of genetic engineering

Increases milk production

Approved by FDA

Has been controversial



Pasteurization Required for

Grade A fluid milk Milk sold in interstate commerce

Involves heating of milk to destroy pathogenic bacteria

Risks associated with raw milk



Homogenization Division of fat globules into small particles

Prevents separation into a “cream” layer

Because of increased dispersion of fat, homogenized milk Has richer flavor Increased viscosity Is whiter



Fortification Vitamin D

Not naturally present in significant levels in milk Added to milk because of relationship between vitamin D,

calcium, and phosphorus in body

Vitamin A Fat reduced milk is fortified with vitamin A to replace

vitamin A lost in with removal of cream



Types of Milk Fluid Milk

Whole 3.25% milk fat

Fat-reduced 2% 1% Non-fat

Flavored milk



Types of Milk Concentrated Fluid Milk

Evaporated 60% water removed

Sweetened Condensed 15% sugar added Concentrated to 1/3 former volume



Types of Milk Dry Milk

Whole or low-fat dry milk

Dried buttermilk

Nonfat dry milk powder Regular Instant



Type of Milk Products Cultured Milk Products

Addition of bacteria cultures Lactose fermented to lactic acid

Yogurt

Buttermilk Low fat cultured milk Originally – milk remaining after cream removed to churn butter

that cultured

Acidophilus milk

Kefir



Type of Milk Products Filled milk

Substitute produced from Nondairy fat such as soybean oil combined with water Nonfat milk solids Emulsifier, color, flavoring

Imitation milk Contains no milk per se May contain casein (milk protein)



Types of Cream Products Fluid Cream

Heavy (not less than 36% fat) Light (30 to 36% fat) Half and half (10.5 to 18% fat) Fat content must be 30% or higher to whip

Sour Cream



Types of Sour Cream Dried

Nondairy products Whipped topping Coffee whiteners May contain casein or whey



Heat in Food Preparation Proteins coagulate Calcium is less dispersed Fat globules coalesce Surface films may form Sugars and protein may brown

Maillard type



Coagulation Acid

Casein is highly susceptible Casein particles unstable at pH of 4.6

Enzyme Rennet

Optimum temperature 104°F/40°C to 108°F/42°C



Coagulation Phenolic compounds

Found in fruits and vegetables

Salts Salts in milk Sodium chloride



Curdling In Cooking Too hot – too long High salt Phenolic compounds

Potatoes Acidic ingredients

Tomato soup Higher fat milk is more stable than low fat milk Non fat dry milk has limited stability Fresh milk is less likely to curdle than “older milk”



Freezing Protein film is weakened

Fat globules coalesce

Dispersion of protein and calcium phosphate affected



Whipping of Cream Temperature and Viscosity

Cold cream whips better than warm

Fat content 30% fat minimum is needed

Amount whipped

Other substances Sugar increases time to whip Sugar decreases volume and stiffness Acidity has no effect



Whipping of Other Milk Products Evaporated milk

Nonfat dry milk



Care of Milk Fresh milk

Cleanliness Cold temperature Prevention of contamination Protect from light exposure

Canned milk Once opened refrigerate



Cheese

Composition Varies with type of cheese and method of coagulation Concentrated dairy food

One pound may contain the protein and fat of one gallon of milk

Nutritive value Most high in

Protein Calcium and phosphorus Vitamin A Sodium



Cheese Manufacture Curd formation

Starter culture Coagulating enzyme

Cutting curd to release whey Heating curd Draining, knitting, salting, and pressing curd Curing or ripening



Ripening Process from the time of precipitation the curd to the

desired end product Aging may be brief or extended

During ripening of cheese Changes in flavor, aroma, texture, and composition Flavor varies with type of organism Swiss Cheese develops holes Lactose converted to other compounds



Grades USDA Grades

U.S. Grade AA and A

USDA Quality Approved



Types of Cheese Vary by moisture

Soft Semihard Hard

Vary by kind and extent of ripening Unripened Mold ripened Bacterial ripened



Types of Cheese Products Cold-pack cheese

Process cheese

Process cheese foods and spreads

Low-fat cheese



Cheese Storage Store cold

Wrap to prevent drying

Mold

Freezing



Cheese in Cooked Foods Grate, and melt at moderate temperature

Well ripened and process cheese preferable Mild cheese more likely to become stringy

Melted or heated too hot Fat may separate Cheese becomes tough and rubbery

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Milk and Milk Products