Flashcards in Lecture 15: Milk, Dairy, and Cheese Deck (68):
Commonly produced in Russia from raw mare's milk
-Milky beverage fermented from cows by Balkans
-Commonly produced in Southwest Asia
-Basically watered down flavored yogurt
What is the Greek word for "milk drinkers"?
When did the colonists introduce dairying to America?
By what year did dairying become a modern industry?
What is milk?
A white, opaque fluid of female mammals for the total sustenance of their offspring
-First fluid secreted by the mammary glands of female mammals
-Clear solution of concentrated protein, vitamins, and antibodies
What factors affect how milk's composition varies?
-Species of cow (size, genetics)
-Region, climate, season
-Type of feed
-Care for animals
Common dairy breeds
What are the 2 types of milk proteins?
What determines the type of milk protein?
Their reaction with acid or chymosin (rennin)
What do caseins form?
What are micelles formed from?
Casein and minerals (phosphate, calcium) in milk
What causes casein particles to clump/curdle?
Chymosin or acid
How is cream made? (2 ways to do this)
Separation of fat globules from the water phase
-fat globules rise b/c it's less dense than water
-separated by centrifuge
Who developed pasteurization?
Why was pasteurization first developed?
To prevent wine and beer from spoiling
Difference between pasteurization and sterilization
-Pasteurization reduces number of microorganisms, but doesn't kill them all
-Sterilization kills all microorganisms
What are the 2 time/temp combos for milk to be pasteurized?
-144 F for 30 mins
-160 F for a few secs
High Temp Short Time pasteurization (160 F for a few secs)
Ultra High Temp pasteurization
-doesn't sterilize milk product, but drastically reduces # of microorganisms
-extends shelf life
-gives milk product cooked lavor
What does homogenization do to milk?
Breaks down the fat globules to prevent them from rising to form a separate layer of cream on the top
How is milk homogenized
Milk is forced through a small nozzle onto a hard surface
How much fat does whole milk have?
Why does milk have to be fortified?
When fat is removed, other lipids including fat-soluble vitamins go with it
What does fortification add to milk?
Fat-soluble vitamins A & D
What are the modern concerns surrounding milk products?
-Use of antibiotics
-Use of hormones
What causes cream to be whipped?
-Foam of air in water
-Proteins stabilize the air bubbles
-Fat increases the viscosity of the liquid
What happens if the cream is whipped past the stiff phase?
-Phase reversal to butter
-Butter squeezes out all the water --> produces butter and buttermilk
Churning breaks the bubble structures and collapses the fat globules together to form butter and the liquid residue (buttermilk)
What makes butter yellow?
Natural vitamin A
Why is butter packaged in aluminum?
Keeps the light out --> light causes rancidity
What affects the quality of butter?
Ratio of amorphous (free) fat to crystallized fat
Process of using different temps to ensure different kinds of crystals form in food
-important for texture
Why is salt added to butter?
What percentage of butter is the liquid water portion?
What part of the butter becomes rancid? Why?
Liquid water portion can harbor bacteria and start turning rancid
What is the original origin and purpose of margarine?
-Goal was to produce a food easy to carry that provided a lot of calories for Napoleon's armies
Today, how is margarine made?
-Made of hydrogenated (partially saturated) vegetable oils
-Emulsified with cultured skim milk
-Flavored and colored
What is a concern surrounding margarine?
Fats vs. Oils
-Oils = unsaturated fatty acids; liquid at room temp
-Fats = saturated fatty acids; solid at room temp
Through what process is vegetable oil converted to margarine?
How does catalytic hydrogenation convert vegetable oil to margarine?
Saturates some of the double bonds --> partial hydrogenation
Downside of catalytic hydrogenation
Converts cis-unsaturations to trans-double bonds --> TRANS FAT
In essence, what is ice cream?
A foam stabilized by freezing the liquid phase
4 component phases of ice cream
-Liquid containing sugar, protein, salts
What is undesirable when making ice cream?
What does the law require for a food to be labeled "ice cream"?
-10% milk fat
-20% total milk solids
-<4.5 lbs per gallon (weight)
What are major factors that determine quality and price of ice cream?
Fat and air content
Standard of Identity
Code of Federal Regulations spells out exactly what standards a product must have to be labeled a certain food name
Process of removing milk fat, usually via a centrifuge
What milk products are fermented?
All curdled milk products
How does fermentation prevent/retard undesirable spoilage and pathogens?
-Competing for nutrients
Bacterial agent added to milk to assure a good fermentation
Live strains of good bacteria that help our digestive system work efficiently
Nutrients bacteria feed on to increase their numbers
Products are both probiotic and prebiotic
-Fermentation replaces some lactose with lactic acid --> sour taste
-Lactose intolerant peeps can drink it b/c less lactose than regular milk
How is today's buttermilk made?
Not drawn off butter churn, but cultured low-fat or skim milk
What is yogurt made from?
Whole or skim milk plus dried milk solids
Who popularized yogurt?
How was cheese discovered?
-When the fourth stomach of a milk-fed calf was used as a vessel for carrying milk
-Stomach contained rennet
-Rennet causes solids to separate from liquids in milk
An extract of milk-fed calves' fourth stomach
Curds cut into blocks and piled up
How are cheeses prepared for ripening?
Surface is often coated with waxes or other materials to protect the cheese within
What determines the hardness of cheeses?