INSTRUMENTATION AND CONTROL FOR MILK PASTEURIZATION AND AIR HANDLING UNIT
Dairy. Milk Processing Pasteurization: Milk is heated to destroy harmful bacteria. – Improves the...
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Transcript of Dairy. Milk Processing Pasteurization: Milk is heated to destroy harmful bacteria. – Improves the...
Dairy
Milk Processing
• Pasteurization: Milk is heated to destroy harmful bacteria.– Improves the keeping quality of milk
without changing the nutrition value or the flavor.
• UHT Processed Milk: Milk that is heated to a higher temperature than regular pasteurized milk to further increase its shelf life.
• Homogenization: A mechanical process that prevents cream from rising to the surface of milk. – This process breaks globules of milkfat
into tiny particles and spreads them throughout the milk
• Fortified: Nutrients have been added in amounts greater than what would naturally occur.–Milk is commonly fortified with vitamins
A and D, along with calcium.
• Milk fat: The fat portion of milk.
• Milk solids: Contain most of the vitamins, minerals, protein, and sugar found in milk.
Types of Milk
• Whole milk: Must contain 3.25% milkfat and 8.25% milk solids.
• Lowfat milk has some of the fat removed.
• Skim/nonfat milk has more fat removed.
Lactose Intolerance
• People experience gas, cramps, bloating, and diarrhea after drinking and eating dairy products.
• Their bodies cannot produce enough lactase, which is the enzyme needed to digest lactose (the sugar found in milk).
Cream
• Heavy whipping cream: most fat
• Light whipping cream: 2nd most fat
• Light cream: (coffee cream) less fat
• Half-and-half: half milk/half cream-has the least about of fat and lowest in calories.
• Sour cream: Made from light cream
• Sour half-and-half: like sour cream w/ less fat.
• Nondairy coffee creamers, whipped toppings, and imitation sour cream products do not contain real cream.
Concentrated Milk Products
• Evaporated milk: Sterilized, homogenized whole or skimmed milk that has had some of the water removed.– By adding an equal amount of water you
match natural milk nutritionally.–More expensive than fresh milk.
• Sweetened condensed milk: Whole or skimmed milk with some of the water removed and a sweetener added. – Used for cooking and baking– You can not dilute this with water to use
as fresh milk.
• Removing most of the water from whole milk produces dried whole milk. – Commonly used in baby formulas– You can reconstitute it and use it like
fluid milk.–Much cheaper than fresh milk
Frozen Dairy Desserts
• Ice cream: a pasteurized mixture of milk, cream, sugar, and stabilizers, flavorings, and sometimes eggs.
• Frozen yogurt: active yogurt cultures, sugar, stabilizer, nonfat solids, and flavorings.
• Sherbet: a pasteurized mixture of sugar, milk solids, stabilizer, fruit juice, and water.
Butter
• Churning pasteurized sweet or sour cream produces butter.– Salt and artificial coloring is added
• Sweet butter is made without salt–May cost more and more perishable
• Whipped butter is butter than has air whipped into it. –May cost more and more perishable
• Margarine is NOT a dairy product– Less expensive– Lower in cholesterol– Contains the same amount of fat and
calories as butter.
Cost of Dairy Products
• Milk and milk products differ in cost depending on fat content, form, and size of container. –Whole milk usually costs more than skim
milk.
Storing Dairy Products
• Cover and store in the coldest part of the refrigerator
• Make sure ice cream is sealed and stored in the coldest part of the freezer.– If it becomes soft, large ice crystals will
form when refrozen.
• Butter should be kept refrigerated.– Freezing will extend it’s shelf life.
Cheese
• Contains protein, calcium, phosphorous, thiamin, niacin, and vitamin A.
• The milk used to make cheese can come from:– Cows, goats, sheep, reindeer
• The milk is coagulated, and the curd (solid part) is separated from the whey (liquid part).
Kinds of Cheese
• Unripened cheese: are ready for marketing as soon as the whey has been removed.– They are not allowed to ripen or age.– Examples: cottage cheese, cream
cheese, farmer’s cheese, and ricotta cheese
– They are mild in flavor, highly perishable, and therefore must be refrigerated.
• Ripened cheese: controlled amounts of bacteria, mold, yeast, or enzymes are used to make these cheeses.– During ripening the cheese is stored at a
specific temperature to develop texture and flavor.
– Over 400 varieties of ripened cheeses, each have a distinctive flavoring, ranging from mild to strong.
• Some ripened cheeses require further storage to develop the flavor, which is called aging. – Cheese is aged anywhere from 2 weeks
to 2 years.
Processed Cheese
• Pasteurized process cheese: is made from a blend of unripened and ripened cheeses.
• Pasteurized process cheese food: contains more moisture and less fat then ppc.
• Pasteurized process cheese spread: has an added stabilizer but less milkfat
• Coldpack cheese: (club cheese) made from a mixture of unripened and aged ripened cheeses blended without heat.
• Coldpack cheese food: contains additional dairy products like cream, milk, skim milk, or nonfat dry milk.
• Imitation cheese: has a large portion of the milkfat replaced by vegetable oils.
Cost of Cheese
• Fully-ripened cheeses often cost more than unripened cheeses or those that ripen for only a short time.
• Pasteurized process cheese costs less than ripened cheese.
• Plain cheese costs less than cheese with added ingredients like nuts and herbs.
Storing Cheese
• Cover or tightly wrap all cheese and refrigerate it to prevent it from drying out and spreading odors and flavors.– Transfer of flavors–Moldy cheese
Food Science Principles
• Scum: Solid layer that often forms on the surface of milk during heating. – It is rubbery and tough, and should be
removed.– If you stir the scum into the milk, it will
float in small particles throughout the milk.
– Stirring the milk during heating or covering the pan will help prevent scum formation.
• Boiling over: Caused by scum formation.– Pressure builds up beneath the layer of
scum, and the scum prevents the steam from releasing causing it to boil over.
– Boiling over can be prevented by using low heat.
• Scorching: Burning that results in a color change.–Milk is brown colored and has an off taste.– This occurs because of the milk sugar
(lactose).– Caramelize: Change to a brown, bitter
substance• This occurs when the lactose is burned in milk• This can be prevented by using low heat or
using a double boiler
• Curdling: Caused by high temps., acids, tannins, enzymes, and salts.– This causes proteins in milk to coagulate
and form clumps called curds.– Foods that contain acids and salt may
cause curdling– Curdling can be prevented by using low
temps. and fresh milk.
White sauce
• White sauce: A thickened milk product made from fat, flour, milk, and seasonings.– Used for making sauces and gravies
• 4 different thicknesses of white sauce:– Thin: forms the base of cream soups
–Medium: to cream vegetables and meat
– Thick: in soufflés
– Very thick: binds the ingredients in croquettes
How to Prepare a White Sauce
• Melt the fat over low heat.• Remove the pan from the heat and quickly stir
in the flour and seasonings.– The mixture should form a smooth paste called a
roux.
• Slowly add the cold milk, stirring constantly but gently until the sauce is smooth.
• Cook the sauce over moderate heat, stirring gently, until it reaches a boil.
• Cook for one minute longer to thoroughly cook the starch.
Cream Soups
• Thickened cream soups: contain vegetables, meat, poultry, or fish that is pureed (mashed to a fine pulp) or cut into very small pieces.– Use a thin white sauce to make.– Cream of mushroom and cream of
tomato soups are popular thickened cream soups.
• Bisques: Rich, thickened cream soups.– Usually contain shellfish that is
shredded or cut into small pieces.
• Chowders: Made from unthickened milk.–May contain potatoes, vegetables, meat,
poultry, or fish
Puddings
• Cornstarch: contains milk, cornstarch, sugar, salt, and flavoring. Served chilled.
• Tapioca: contains milk, tapioca, sugar, salt, eggs, and flavoring. Served chilled.
• Bread/Rice: contains milk, sugar, salt, eggs, and flavoring. Serve warm or chilled.
• Indian: contains milk, cornmeal, eggs, salt, and molasses.
• Some pudding recipes require scalded milk, which means heating to just below the boiling point.
Gelatin Creams
• Gelatin: A gummy substance made from bones and some connective tissues of animals.– Colorless and tasteless
• Gelatin creams: Milk-based desserts thickened with unflavored gelatin– Spanish creams, Bavarian creams, and
charlottes
