Milk Flashcards
Define the chemical composition of milk. What is the emulsion, the suspension? What is it suspended in?
Milk is an emulsion of fat globules and a
suspension of casein micelles suspended
in an aqueous milk serum phase
Where is milk secreted from? What is it used for?
White yellowish secreted from the
mammary gland to serve as nutrition for
the newborn
Where and when does milk originate from?
People have been using milk for thousands of years
Dates to ancient Babylon, Egypt and India
What is milk a source of?
o Complete protein o B vitamins o Vitamin A o Vitamin D o Calcium
What is the % of calcium consumed from dairy?
80%
What do the proteins in milk do during during food processing?
Proteins used in processed foods to improve nutritive value
What do the caseinates in milk do during food processing?
Caseinates used as emulsifying and stabilizing agents
How does lactose help for baked goods?
Lactose helps with browning of baked goods
What does dairy alter during food processing?
Used to alter texture, flavor, moisture, protein content
What is the composition of milk?
H2O: 87% CHO: 5% Fat: 3.7% Protein: 3.4% Minerals: 0.8%
Name the 2 components of milk solids.
- Milk solids non-fat
- Milk solid fat
Name the 3 components of milk solids non-fat
Lactose, Protein, Minerals
What are the 2 types of proteins that can derive from milk?
- Casein protein
- Whey protein
What nutrients does milk lack?
- Vitamin C & E
- Iron
- Complex CHO
- Fiber
Which amino acid is in milk? Which B vitamin is specifically in milk?
Tryptophan and vitamin B2 (riboflavin)
What % of calcium RDI is in a glass of milk? Protein? Calories?
- 30% calcium
- 16% protein
- 85 kcalories
Which protein is the primary protein found in milk?
Casein
Which milk protein can be added to foods as an emulsifier?
Whey
How is casein extracted?
Extracted by acid or enzymes (rennet)
Which milk protein is the liquid portion of milk?
Whey
What is whey composed of?
Lactalbumin and lactoglobulin
Which milk protein can be added to improve nutritional value?
Casein AND Whey
Which milk protein separates from curd during cheese production?
Whey
What else can whey do?
Improves mouthfeel, moisture retention and flavor
How many fatty acids are in milk fats?
Over 400 FA
What is the most variable component in milk?
Milk fat
What are the roles of milk fat?
Contributes to flavor, physical (mouth feel), and chemical properties
Describe the structure of milk fats.
Triglycerides surrounded by phospholipid protein membranes
Name the 2 short chain fatty acids in milk fat.
Butyric acid, caprylic
Name the 3 fatty acids in milk fat.
Myristic, palmitic, stearic
What are the components of the fatty acids in milk fat?
o Saturated FA = 66%
o Monounsaturated FA = 30%
o Polyunsaturated FA = 4%
Which milk protein the one that is found in the largest amount?
Casein
What is the Framingham Heart Study?
Longitudinal association (since 1948) between dairy consumption and changes of body weight and waist circumference
How many different types of caseins?
Alpha, Beta, Kappa, y
Which type of casein prevents milk from coagulating?
Kappa
Which type of milk protein coagulates? Which stays in solution?
Coagulates: Casein
Solution: Whey
Is there evidence that milk increases the risk of heart disease and obesity?
No not yet,
People who drink 1-3 milk drinks per day are less obese and have a smaller waist circumference
Why aren’t people who drink more milk obese?
Since fat and protein (in milk) increase satiety (fuller for longer)
How many carbohydrates per cup of milk?
12g
What is the primary CHO found in milk?
Lactose
What turns lactose to lactic acid? What does it do?
Bacteria
Gives flavour to cheese, yogurt, sour cream
Name a couple of sources of milk from Canada’s food guide.
- Milk (250 mL) - SKIM (1 or 2% bcos high in sat fat)
- Yogurt (3/4 cup)
- Cheese (50 grams)
Define lactose intolerance.
- A condition in which a person is unable to
digest lactose - Insufficient quantities of lactase brush
border enzyme
What are the symptoms of lactose intolerance?
Abdominal cramps/ bloating
Flatulence
Nausea
Diarrhea
Which ethnicity has a genetic advantage in terms of lactose intolerance?
European descent
Lactose intolerance affects how many Canadians? Americans?
- 7 million Canadians
- 30-50 million Americans
Why can lactose intolerance develop?
Lactase can go down throughout adulthood
Milk allergies occurs in what percentage of infants?
Occurs in 2-7.5% of infants
Which protein is the antigen that the body reacts to?
B-lactoglobulin
What are the symptoms of milk allergy?
Vomiting o Nausea o Wheezing, chronic cough o Skin rash o Headaches
Name some sources of milk alternatives.
Soy milk oRice milk oAlmond milk oCashew milk oCoconut milk oHemp milk
What is the issue with milk alternatives?
Since most (apart from soy) do not have nearly as much protein as regular milk
Name 2 nutrients milk is fortified with.
- Vitamin D
- Vitamin A
Why is milk fortified with vitamin D?
oFound naturally in few foods so it was added to milk – a staple
o To prevent the incidence of rickets in children
o Prevent osteoporosis
Why is milk fortified with vitamin A?
Vitamin A naturally found and is a fat soluble vitamin
o When fat content is reduced – vitamin A is lost
What are the different pasteurization types? What makes them differ?
- Pasteurization
- Ultrapasteurization
- Ultrahigh-temperature pasteurization (sterilizing)
DIFFER BASED ON TEMP AND TIME
Name characteristics of regular pasteurization.
Heating milk below it’s boiling point for a short time to reduce foodborne illness
o Destroys 95-99% of pathogenic and non-pathogenic bacteria, yeasts and molds
o To ensure adequacy – food processors measure alkaline phosphatase activity, an enzyme found in milk
- most commonly used
Name characteristics of ultrapasteurization.
Uses higher temperatures for shorter amount of time
o 15 second process
o Extends shelf life
Name characteristics of ultrahigh- pasteurization.
o 2 second process
o Sterile packaging technique
How does industry know if milk is properly pasteurized
Measure alkaline phosphatase
Why does fat float to the top of milk when raw?
Fat is less dense than water
What does homogenization prevent?
Creaming, thick yellowish layer of cream
Does the mechanical process of homogenization have an effect on the nutritional value?
No
How does homogenization coagulates quicker? What is this good for?
- In presence of heat
- Good for making pudding, white sauces and cocoa
Name some examples of cultured dairy products (microorganisms added).
Buttermilk, yogurt, acidophilis milk, kefir, sour cream
Milk is graded according to what?
Its bacteria count
Highest grade = lowest bacteria count
Who grades milk?
USDA
Milk products crossing state lines must be what?
Pasteurized
Differentiate condensed and evaporated milk.
Both are evaporated milks.
Condensed has ALOT of sugar
Name 6 benefits of milk.
Bone health
- Weight management
- Probiotics for gut microbiota health
- Heart health
- Protective against colorectal cancer
- Source of conjugated linoleic acid -> isomer of linoleic acid
What are the benefits of CLA?
- Anti-carcinogenic properties
2. Anti-atherogenic
Explain the composition of active cultured yogurt.
Don’t heat the yogurt before packaging
fermentation process continues, so microorganisms are still alive when you digest them
What’s the difference between greek yogurt and regular yogurt?
Strain the yogurt more, so more whey is put aside, which makes it very rich in fat and protein (more bang for $)
How long can milk be stored for in the fridge?
3 weeks
How long can yogurt last in the fridge?
- Eat within 10 days
- Can last up to 3-6 weeks
How long can buttermilk last in the fridge?
Use within 3-4 days
Lasts up to 3 weeks
How long does sour cream lasts in the fridge?
Use within a few days once opened
How long do nonfat dry milk lasts and sweetened condensed milk?
up to 1 year
How long does ultra-pasteurized milk lasts?
up to 3 months
True or False: in milk, denatured proteins often separate from liquid by coagulation
True
True or False: adding acid to milk will cause whey to curdle.
False, it is casein
Once dry milk products are opened, how do you treat them?
Like fresh milk