I B Food science & nutrient composition: eggs, milk, little bit of grains Flashcards
air space in an egg, what happens as it ages?
air space becomes larger with age
is the color of the shell of an egg e/t food value or quality?
no!
good quality of egg is indicated by?
high proportion of thick white (candling)
what is more concentrated: yolk or white of an egg?***
yolk: more PROTEIN by weight
nutrients of an egg
protein, fat, vitamins A, D, riboflavin
how is fat present in an egg?
emulsified form: naturally occurring oil in water in the yolk
how are eggs graded?***
candling- pass an egg in front of bright light to view contents
what is the grading/candling of an egg based on?
thickness of white, location and condition of yolk (NOT color or size)
grades of eggs***
AA, A, B
how is size classified for eggs?
based on weight per dozen (ex: jumbo, extra large, large, medium, small, peewee)
how long do eggs last for?
Grade A can last for 6 months in cold storage
do fresh eggs sink or float? quality of shell of fresh egg?**
- FRESH = SINKS in cold water (old float)
- shell = DULL, ROUGH
use of coagulation?
used to bind, give firmness, stability, coats food, browns, clarifies liquids
syneresis is AKA? what is it?***
AKA WEEPING, LIQUID RELEASED FROM A COAGULATED PRODUCT
when does syneresis occur?***
too high of a temperature or too low of a temperature for too long a long
what does syneresis create?***
tough, watery product
what does an acid do to an egg white foam? how?***
acid = STIFFENS egg white foam, TENDERIZES THE PROTEIN
best temperature to whip egg whites? why?**
ROOM TEMPERATURE- whip more QUICKLY, yield a LARGER VOLUME due to LOWER SURFACE TENSION
what does sugar do to an egg white foam?
stabilizes it
what has a more stable emulsion- egg yolk or egg white? why?**
egg yolk = more stable emulsion, has more protein! (by weight)
yolk is a naturally occuring _____ emulsion
oil in water
what substance helps yolk act as an emulsifier?
lecithin
what is mayonnaise?
food emulsion: stabilized by egg yolk
what do vinegar and salt do to eggs when cooking?
improve shape- quicken coagulation/firmness
surface of yolks turn ____ when overcooked or allowed to cool slowly; why?
green; combination of iron from the yolk and sulfur from the egg (think: hard boiled eggs)
dried heat methods- overcooking does what to eggs? undercooking does what?
- overcooking = toughens
- undercooking = excessive shrinkage once removed from oven
custards: the larger % sag, the more _____
tender the gel
what happens if you try to make a custard with dehydrated eggs?
may be grayer and less yellow, have an eggy flavor, be watery
what is added to yolks to stabilize then for frozen eggs?
salt, sugar
dried eggs- packaging
vacuum-packed in nitrogen gas
what are baker’s special eggs?
sucrose added to improve foaming ability
nutritional qualities of egg substitutes****
HIGHER IN SODIUM, lower in fat calories and cholesterol
what happens to eggs when they are stored in the refrigerator for too long?***
LOSS OF CO2 –> BECOME MORE ALKALINE
what should you do if you are cooking with old eggs?***
INCREASE ACID (b/c they become more alkaline) –> ex: cream of tartar, lemon
composition of milk
mostly water (87% DNK # probably), some fat, some carbohydrate (lactose), some protein
type of protein in milk***
80% casein
what is whey?***
LACTOSE, liquid that drains from curd of clotted milk
vitamins and minerals in milk
- GOOD source of: calcium, phosphorous, riboflavin, A & D
- LOW in: iron
processing of milk
pasteurization: destroys bacteria, 145F for 30 min or 160F for 15 seconds
homogenized milk
high pressure BREAKS FAT GLOBULES to 1/5 regular size, film of protein surrounds each globule
potential problem with homogenized milk
more susceptible to action of LIPASE, but pasteurization process destroys lipase
vitamin D milk
400 USP units added per quart of milk by feeding the cow vitamin D, irradiating the milk, or adding the vitamin
amount of fat in: (general #s, probably DNK specifics)
- 2% milk
- lowfat milk
- skim milk
- 2% milk = 1.5-2.25%
- lowfat milk = 0.5-2%
- skim milk = <0.5%
types of concentrated milks
- evaporated milk
- sweetened condensed milk
- dried whole milk
- dried skim milk
evaporated milk
60% water removed; no less than 7.9% milk fat
why is evaporated milk brown?
carmelization of lactose in canning
sweetened condensed milk
concentrate (evaporated) whole milk; add 15-18% sucrose or glucose
dried whole milk
26% fat, does not keep well
dried skim milk
<1.5% fat, keeps well
what is cultured buttermilk?
add lactic acid bacteria to skimmed or partially skimmed milk
when using buttermilk in place of regular milk in a recipe, what do you need to do?***
increase baking soda! –> buttermilk is more acidic, baking soda is basic (making it more neutral towards the pH of regular milk)
what is sweet acidophilus milk?***
skim milk + acidophilus bacteria, REDUCES/HAS LESS LACTOSE
kefir
fermented by Lactobacillus kefir; adds CO2, about 3% alcohol
low lactose milk- Lactaid
treated with lactase in processing or add the enzyme to regular milk and hold in the refrigerator
yogurt
coagulated product; fermentation of milk sugars by lactic acid bacteria
filled milk
skim milk, vegetable fat (coconut oil), water; illegal in some states
imitation milk
resembles milk but contains NEITHER MILK FAT NOR other DAIRY INGREDIENTS (made from casein derivatives or soybean protein and vegetable oils)
when milk is HEATED, what happens?**
WHEY PROTEIN PRECIPITATES out on bottom of pan or on surface of milk
to prevent a film from forming in milk, what should you do?
cover or beat the milk to produce a foam
to prevent milk from coating the sides of the pan, what should you do?
heat over water
what is curdling?
clumping of bits of milk proteins
to prevent curdling of milk, what should you do?**
add ACID- PRECIPITATES CASEIN
butter is how much milk fat?***
80%
margarine is how much fat?**
80% vegetable oil or animal fat
why does butter turn rancid?
takes up oxygen and releases hydroegn
types of cream and amount of fat, rank from most to least:***
- whipped cream
- light or thin
- medium
- sour cream
- heavy or thick
- half and half
1) heavy/thick, medium, whipped cream = MOST fat
2) light or thin
3) sour cream
4) half and half
what enzyme should be added in cheese production? why?**
**RENNET - hardens casein, can separate from whey/liquid
[coagulate casein to form the curd, more able to separate curd from the whey (liquid)]
uncured cheese***
must be refrigerated –> cottage cheese, cream cheese
cured cheese***
additional whey (liquid) removed, salt added, ripened
% moisture content high to low of cheese: (which is the most, which is medium, which is the least)***
- cheddar
- gorgonzola
- mozzarella
- parmesan
- bleu
- swiss
- cottage
- cream
- camembert
(just think of the cheese types, DNK #s)
- MOST moisture: cottage
- MEDIUM: cream, mozzarella
- LEAST: (everything else) camembert, bleu, swiss, cheddar, gorgonzola, parmesan
what is processed cheese?
blend of several natural cheeses (American cheese)
benefit of processed cheese?
better for cooking- emulsifier added, fat won’t separate out
what should you do to prevent stringy, curdled-looking cheese products?
cook for a short time at moderate temperatures
anatomy of a grain
- outer layer = hull and bran
- endosperm = starchy, protein
scutellum
in the germ, contains most of the thiamin
nutrients in a grain
vitamin E (in germ), thiamin, riboflavin, phosphorous
what is milling?
separating large flour particles from fine particles
farina
inner portion of wheat kernel
quick-cooking cereals have what added?***
DISODIUM PHOSPHATE (ex: instant oatmeals)
problem with disodium phosphate?***
need to avoid on low sodium diets
rank the amount of protein (+ #) and rate the gluten:***
- all-purpose
- bread
- pastry
- cake
(1) bread = strong gluten, 11.8% protein
(2) all-purpose = less gluten, 10.5% protein
(3) pastry = weaker gluten, 7.9% protein
(4) cake = least and weakest gluten (7.5% protein, maybe DNK?)
self-rising flours have?
baking powder, flour, salt
examples of alimentary pastes?
= pasta
—–durum wheat & noodles
durum wheat
high in gluten, starch is ground to make semolina flour after bran and germ are removed
noodles
contain egg yolk or egg solids
how to cook rice
cook in amount of water that will be absorbed during cooking (1c rice = 2c water)
