Lab 8 : Milk Products, Fermented Milk Products, Pro-biotics and Energy-dense Applications. Flashcards
What does UHT stand for?
Ultra-high Pasteurized (milk)
How is UHT milk treated?
-Subjected to high heat
-Packaged in aseptic container
(contains no bacteria)
What reaction for Lactase catalyze?
Lactose to glucose and galactose
Who is intended to drink lactose-reduced milk?
people with lactase deficiency
What gives evaporated milk it’s color and taste?
Mailard reaction
slight caramel taste
What maintains the viscosity of evaporated milk?
Stabilizers and preservatives
How was buttermilk traditionally made?
by-product of butter-making
How is buttermilk made today?
By adding bacteria culture to low/non- fat milk
transforms lactose to lactic acid = sour taste
What can buttermilk be placed with in a recipe?
By adding vinegar or lemon juice to normal milk (10ml:250ml)
Why would Acidophilus milk be consumed?
To help replenish the GI with Lactobacillus Acidophilus.
After antibiotic treatment
What bacteria does Acidophilus milk contain?
Lactobacillus Acidophilus.
How is sour cream made?
Pasteurized milk - soured by Streptococcus Lactis
which produces lactic acid
Can sour cream be home made?
Yes, by combining 30ml buttermilk and 500ml fresh cream and letting it sit at room temp for 24 hrs.
What bacteria is used to make yogurt?
Lactobacillus Bulgaricus
and
Streptococcus Thermophilus
Why is Gelatin added to yogurt?
used as stabilizer / solidifier
What is the function of Pectin when added to yogurt?
used as stabilizer / solidifier
Why is carrageen added to yogurt?
used as stabilizer / solidifier
Why are stabilizers added to yogurt?
To prevent the whey (yellowish liquid) from separating from commercial yogurt.
What is Kefir?
A fermented milk product similar to yogurt.
What makes kefir different?
Also fermented with yeast.
What is the texture of Kefir?
Frizzy, frothy, piquante, bitter drink
Where is Kefir traditionally used in dishes?
Russia, Eastern Europe, Middle East.
How is cheese made?
Milk products coagulated/curdled.
Then separated from Whey.
Does cheese keep the nutrients found in milk?
Yes, highly concentrated form of milk.
Rich in nutrient.
What nutrients are found in cheese?
Protein, Calcium, Riboflavin, Vitamin A, Sodium
What influences the flavor, body and texture of cheese?
Type of milk used Bacteria species Quantity of salt /seasoning /colours Processing method Mold used (during inoculation) Environment during ripening (temp, humidity...)
Two classes of cheeses.
Ripened
Unripened
Which classification of cheese has a more moisture content?
Unripened
What are examples of unripened cheeses?
Cottage cheese
Ricotta
What type of curds does unripened cheese have?
Soft and fragile
How are soft cheeses usually made?
Coagulation by acid
Which classification of cheese has a lower moisture content?
Ripened cheese
What type of curds does ripened cheese have?
Touch and rubbery
How are ripened cheeses made?
Coagulated by action of enzyme (Rennin)
How long are cheese left to ripen?
3 months to 2 years
How quickly much unripened cheeses be eaten?
Within a few weeks
What is added to milk, to ripen cheeses?
Enzymes, Bacteria, Molds or Yeasts
What happens to casein during ripening?
Hydrolysed to amino acids & ammonia.
What happens to the fats during ripening?
To fatty acids and acetate
What happens to lactose during ripening?
Turned to lactic acid
What is condensed milk?
Evaporated milk with sugar and stabilizers added?
Is condensed milk just as nutritious as evaporated milk?
No! It tends to be higher in fat, sugar content and calories.
What type of recipes is condensed milk used in?
Desserts and sweets
What does NFDM stand for?
Non-fat dehydrated milk
What type of milk is usually used for making NFDM products? and why?
Skim milk
Because it is less perishable
What is whey protein powder used for?
Increase energy and protein content of food and beverages.
What factors cause milk proteins to coagulate?
Heat
Acid
Enzymes
What temp do Whey proteins begin to coagulate?
66 C
What are the whey proteins present in milk?
Lactoglobulin and Lactalbumin
What is contained in the skin on the surface of milk when it is heated?
Fats, Minerals, Coagulated Whey proteins
What precipitates along the sides and bottom of the pan when heating?
Calcium Phosphate, Whey proteins
What can be done to prevent the milk from being scorched during cooking?
1) Use of a double boiler
2) Stirring it constantly
What is milk’s predominant protein?
Casein
Is casein effected by cooking?
No
What circumstances may cause casein to curdle?
A higher concentration of proteins.
ex. evaporated milk, sweetened condensed milk
What happens to milk when a unopened can of condensed milk is boiled?
Casein coagulate and causes the caramelized milk to gel.
What does heat do to unstable milk products?
It accelerates coagulation.
When should sour cream be added to a hot dish?
Right before serving, to prevent separation.
What is sour cream sensitive to?
Heat
What is the normal pH of milk?
6.5 - 6.7
What pH does casein start coagulate?
Below 5.2
Why does casein in milk coagulate below a certain pH?
Negative charges that stabilize Calcium phosphocaseinate micelles are neutralized (by H+ from acidic environment)
What enzyme is used for manufacturing cheese?
Rennin (sold as Rennet)
What are the two steps that take place when rennet is added to milk?
1) Rennin cleaves kappa-casein bond
(forming para-kappa casein)
2) Exposed chemical group reacts with Ca
(form curds)
How would you minimize the effects of milk curdling when combined with food?
1) Add acid to milk (not milk to acid)
2) Heat both before combining (acid food & milk)
3) Thicken acid/milk before combining
4) Serve combination promptly
What do milk foams consist of?
Air bubbles surrounded by thin layer of protein.
Fat interspersed as a stabilizer.
What factors effect milk/cream foams?
1) Viscosity (Increasing viscosity of milk = more stable foam)
2) Fat concentration (increases formation and stability)
3) Temperature (cool temp = fat droplets to harden)
4) Sugar (delays curdling)
What happens to cheese when it overheated?
Proteins coagulate (become tough and rubbery) Fat emulsion may break (fat separates)
Which type of cheese is more resistant to heat?
Firm cheeses
Which type of cheese is better used for cheese sauces?
Ripened, sharp cheeses blend better (more flavor).
What are characteristics of a nourishing drink?
High protein / High Energy
Skim milk is common base (Full cream milk for more energy)
What can be done to reduce the amount of saturated fat in nourishing drinks?
Skim milk and oil.
What does whey powder contain?
Complete high quality proteins
What is yogurt cheese?
A low fat, creamy cheese.
How can yogurt cheese be made?
At home, suspend the yogurt in cheese cloth, allowing the liquid to drip out over night.
