Domain 1 - Food Science, Nutrient Composition of Foods Flashcards
what is the water content of fruits and vegetables
75-93%
what is the cause of crispness (state of turgor) of fruits and vegetables
osmotic pressure of water filled vacuoles
what is the limiting amino acid in soybeans
methionine
what is protopectin converted to
pectin (indicates ripe fruit)
what is pectin converted to
pectic acid (overripe fruit)
what accelerates ripening of fruits during storage?
ethylene gas
what temp should frozen fruit be stored at?
0 degrees F
what fruits ripen best at room temp?
avocado, banana, pear, tomato
how can you delay aging in apples?
store in a controlled atmosphere (reduced oxygen)
why do fruits low in vitamin C darken rapidly when cut? how can you prevent this?
enzymatic action - to prevent dip in citrus juice, add sugar before freezing, heat to boiling
what does a Brix hydrometer measure
% sucrose by weight
describe chlorophyll…… more like borophyll
green, Insoluble in water
olive green in acid (pheophytin)
bright green in alkaline (chlorophyllin)
describe carotenoids
yellow/orange, insoluble in water
little color effect in acid or alkaline
lycopene - red in tomato/watermelon, overtone in aprictos (antioxidant/phytochemical)
what are 2 types of flavinoids
anthocyanins, anthoxanthis (flavones) - they are both soluble in water
describe anthocyanins
red, blue, purple
Soluble in water
bright red in acid
bluish tone in alkaline
describe anthoxanthins
white
soluble in water
colorless in acid
yellow in alkaline
what provides flavor in peas and corn
sugars
what provides flavor in onion and cabbage
sulfur
what is glutamic acid used in
MSG (form of salt)
what provides flavor is fruits (3 things)
acids, sugars, aromatic compounds (such as tannins - cause astringent feeling in mouth, underripe banana)
describe Grade A canned fruits and vegetables
fancy - desserts, salads
describe Grade B canned fruits and vegetables
choice - processed
describe Grade C canned fruits and vegetables
standard - puddings, pies
what are the grades of fresh produce
fancy, extra #1, extra #2, combination, #2
what is the green color under potatoes skin due too
chlorophyll that develops when potato is exposed to light during storage
potatoes contain what compound which is a natural toxicant
solanine
what are benefits of microwaving vegetables
less time, retain color, vitamins, not a large difference in eating quality
describe a #10 can (most important!)
6 cans per case, 6lb 9oz, 13 cups in each can, 20-25 servings
describe a #3 can
12 cans per case, 46 oz, 5 3/4 cups, serves 12-15
describe a #2 1/2 can
24 cans per case, 1lb 13 oz, 3.5 cups, serves 6-8
describe a #2 can
24 cans per case, 1lb 4 oz, 2.5 cups, serves 4-6
describe a #300 can
24 cans per case, 14-16 oz, 1 3/4 cups, serves 3-4
what is the structural part of the tendon that surrounds muscle, and what happens to it in heat
collagen - in heat it is hydrolyzed to gelatin and becomes tender
what happens to elastin in heat
little change, it is resistant to heat
in potatoes, starch changes to what during storage
sugar
muscle is composed of bundles of fibers called what
myofibrils
what holds fibers in bundles
sheet of connective tissue
what identifies a cut of meat
shape of bone (round bone - leg, t-bone - back and ribs, etc)
what % protein is meat/poultry/fish
16-23%
what vitamins/minerals are meat/poultry/fish high in
thiamin, niacin, riboflavin, iron, copper, trace minerals
pork is an especially good source of what
thiamin
calcium content is higher in what types of fish
canned fish with bones, oysters, shrimp
fish has ____ fat and _____ moisture than meat
less, more
why is TVP mixed with ground meats
more servings, lower costs
soy protein adds ______ due to _____ content
juiciness, water
what is the main contributor to meat color
myoglobin
myoglobin exposed to oxygen turns front red to what color
brown, and green with further breakdown
how does acid (vinegar) and salt increase tenderness
increase water-holding capacity of muscle and lowers pH
how should meat be aged and ripened
hold in cold storage for about 10 days
change in muscle protein by enzymes increase _____ of muscle
water-holding capacity
what may extend storage life of meat
anaerobic (sous vide) packaging - vacuum packed, stored unfrozen at 0 C
what is MAP (modified atmosphere packaging)
air in packaging is removed and replaced with gases (carbon dioxide, nitrogen)
when is USDA inspection and grading of meat done
at slaughter
which act assures the consumer that animals are healthy at slaughter and meat is fit for consumption
Wholesome Meat Act of 1967
what are the grades of meat
prime, choice, select, standard
what are grades of meat based on
maturity of animal, marbling, color, texture
which grade has the least marbling and which has the most
standard has least, prime has most
which cuts of meat are most tender
loin (pork chops), backbone
which cuts of meat are medium tender
shoulder (chuck)
which cuts of meat are least tender
flank, brisket
what is the proper temp for a roast
325 F
when should a meat thermometer be inserted
before cooking
a ____ cooked roast yields less waste
slow
what meats have a safe internal temp of 145 F
pork, beef, veal, lamb, steaks, roast, fish
what meats have a safe internal temp of 160 F
ground beef, ground veal, ground lamb
what meats have a safe internal temp of 165 F
turkey, chicken, duck
collagen is hydrolyzed to _____
gelatin
why must tough cuts of meat be cooked well done
they have more collagen which needs more time to be softened
why do meat surfaces become brown
breakdown of pigments
heat _____ globin
denatures
when meats are heated, iron is _______
oxidized
why are cured meats pink
nitrites
what types of cuts should be cooked with dry heat
tender cuts such as backbone, loin, sirloin
what are dry heat cooking methods
frying, broiling, roasting
what is “carry-over cooking”
after roasting, meat is removed from oven and for about 10 minutes internal meat temp will rise 15-25 F
how long should a roast stand before carving
30 minutes
what types of cuts should be cooked with moist heat
less tender cuts with more connective tissue, tough cuts (round, chick, brisket)
how should a bottom round be cooked
in water for several hours
what are moist heat cooking methods
braising, simmering, steaming, stewing
_______ enzymes such as _____ tenderizes meat
proteolytic, papain
fresh fish with head attached should have ______ red gills, _____ skin
bright, shiny
what is surimi
purified and frozen minced fish with a preservative
egg yolk is a naturally occurring _______
oil in water emulsion
a good quality egg is indicated by what
high proportion of thick white
in an egg, what becomes larger with age
air space within the egg
what holds an egg yolk in the center
chalazae (yolk anchor)
what vitamins/minerals is egg rich in
vitamin A, D, riboflavin
what is color of yolk dependent on
amount and type of pigment in a hen’s diet
what are grades of eggs
AA, A, B
grading of eggs is based on what
thickness of white, location and condition of yolk
what is candling
passing an egg in front of bright light to view contents, helpful when grading and judging quality
what are the sizes of eggs
jumbo, xl, large, medium, small, peewee
how long can egg freshness be maintained in cold storage (29-32F)
6 months
a fresh egg will _________ in a pan of cold water and has a ______ shell
sink to the bottom, dull and rough
at what temperature does protein coagulate
62-70 C
what is syneresis
weeping, liquid released from a coagulated product
when does syneresis occur
when cooked at too high of a temp or too low of a temp for a long time - leads to tough, watery product
what will stiffen an egg white foam
acid - it will tenderize the protein and allow it to extend more easily
sugar will also stabilize egg white foams
how are egg white foams compared
measure specific gravity (relative density of a substance in relation to that of water)
weight of given volume / weight of same volume in water
egg whites at room temperature whip more quickly and yield a larger volume due to _______ surface tension
lower
what helps an egg yolk act as an emulsifier
lecithin
what stabilizes the egg yolk emulsion
lipoproteins
why do eggs yolks yield stiffer, more stable emulsions than egg whites
they have more protein by weight
what can hasten coagulation in egg cooking
vinegar and salt
why do egg yolk surfaces turn green when overcooked or cooled to slowly
iron from the yolk and sulfur from the whole egg create ferrous sulfide
in dry heat cooking of eggs, what will result from undercooking
excess shrinkage
in dry heat cooking of eggs, what will result from overcooking
tougher product
the larger the % sag, the ______ tender the gel
more
egg substitutes are often ______ in sodium
higher
what differences occur when using egg substitutes
color and flavor differences
dried eggs are ____ % white, ____ % yolk
70, 30
dried eggs can be vacuum packed in what
nitrogen gas
what is added to improve foaming ability in bakers special eggs
sucrose
if eggs are stored in the fridge for too long, whites become _____, yolks ______, and odors are ______
watery, flatten, absorbed
if eggs are stored in the fridge for too long, ______ and ______ is lost
water and carbon dioxide
loss of carbon dioxide causes eggs to be more _______
alkaline
milk is a good source of what vitamins and minerals
calcium, phosphorus, riboflavin
Vitamin A, D
milk is not a good source of what mineral
iron
what is the % composition of milk (water, macronutrients)
87% water, 3.7% fat, 4.9% cho (lactose), 3.5% protein (complete hbv)
the protein in milk is ____ % casein
80% (precipitated at ph 4.6, forms soft curd)
liquid that drains from curd of clotted milk is known as what
whey
how is milk pasteurization done
heat to 145 F for 30 min or 160 F for 15 seconds
what is the purpose of pasteurization
destroy pathogenic bacteria
name the components of whey (5)
lactose, lactalbumin, lactoglobulin, water soluble vitamins, minerals
types of milk
high pressure breaks fat globules to 1/5 regular size; film of protein surrounds each globule; more susceptible to action of lipase, but the pasteurization process destroys lipase
homogenized
types of milk
400 USP units added per quart of milk by feeding the cow this vitamin, irradiating the milk, or adding the vitamin
vitamin D milk - must be labeled
name the 4 concentrated milks
evaporated milk (60% water removed) sweetened milk (add 15-18% sucrose or glucose) dried whole milk (26% fat, does not keep well) dried skim milk (not more than 1.5% fat, keeps well)
name the 3 fermented milks
cultured buttermilk
sweet acidophilus
kefir
2% milk has ______ % fat, low fat milk has _____ % fat, and skim milk has ______ % fat
1.5-2.25%
.5-2%
<0.5%
in cultured buttermilk, add ____ ____ bacteria to skimmed or partly skimmed milk
lactic acid bacteria
in place of using buttermilk in place of regular milk in a recipe, increase ________
baking soda
sweet acidophilus milk (skim milk + sweet acidophilus bacteria) reduces ______
lactose
the coagulated product of fermentation of milk sugars by lactic acid bacteria is known as
yogurt
when milk is heated, what happens to they whey protein?
it precipitates out on bottom of pan or on surface of milk
how do you prevent milk from curdling?
add an acid slowly and agitate
in milk, an acid precipitates _______
casein
butter is 80% __________ and margarine is 80% ___________ or ____________
milk fat
vegetable oil or animal fat
does butter or margarine turns rancid as it takes up oxygen an releases hydrogen
butter
what are the types of cream
heavy or thick medium whipped cream light or thin sour cream half and half
which creams have the highest fat content
heavy or thick >36% fat
medium 30-36% fat
whipped cream 35% fat
during cheese production, what enzyme is added, which coagulates casein and forms curd
rennet
what are the 3 types of cheese
uncured (cottage cheese)
cured (additional whey removed, salt added, ripened)
processed (blend of several natural cheeses)
what is the emulsifier added to processed cheese
disodium phosphate- makes cheese better for cooking; fat will not spread out
what are the main structural parts of grains and cereals
starchy endosperm rich in protein
outer layer of hull and bran
scutellum within the germ - contains most of thiamin
what vitamins and minerals are found in grains and cereals
vitamin E (in germ), thiamin (scutellum), riboflavin, phosphorus
grains are ____% starch, ___ % fat found in the germ, and contain ______ proteins
75%, 2%, partially complete
what is the inner portion of a wheat kernel called
farina
quick-cooking cereals have ________ added
disodium phosphate - makes cereal alkaline so particles swell faster
avoid this on low sodium diets
strength of gluten and protein content have a negative or positive relationship
negative - the stronger the gluten, the more protein; the weaker the gluten, the less protein
name the 8 different wheat flours
graham bread (hard wheat) all-purpose (blend of hard and soft wheat) pastry (soft wheat) cake (soft wheat) enriched (with B vits, iron and folic acid) instant blending self-rising
place the following flours in order from strongest gluten and most protein to weakest gluten and least protein: all-purpose, cake, pastry, bread
bread (strong gluten, 11.8% pro)
all-purpose (less gluten, 10.5% pro)
pastry (weaker gluten, 7.9% pro)
cake (least and weakest gluten, more starch, 7.5% pro)
what is gluten made from and what does it do
it is made from gliadin and glutenin through process of hydration and mixing
it gives elastic properties, forms framework, holds in leavening agent
what is the color of flour due to
carotenoids
if an oxidizing agent is added to flour, what is it labeled as
bleached - natural agents cause oxidation and turn flour from creamy yellow to white
adding bran increase or decreases volume of end product
decrease - increase flour and liquid to compensate
name 3 leavening agents
steam
air
carbon dioxide (from yeast, baking soda, baking powder)
how do you incorporate air into baked flour mixtures
beat, sift, fold, cream
what does the action of yeast on sugar yield
carbon dioxide and alcohol
________ is produced from the action of acid on baking soda
carbon dioxide
- acids include sour milk, cream of tartar, molasses
baking soda + a dry acid + corn starch =
baking powder
baking soda provides
carbon dioxide
cornstarch keeps contents ____
dry
a dry acid reacts with baking soda to release
carbon dioxide
a dry chemical leavening agent used to increase the volume and lighten the texture of baked goods - it works by releasing carbon dioxide gas into a batter or dough through an acid-base reaction, causing bubbles in the wet mixture to expand and thus leavening the mixture
baking powder
what are 3 types of baking powder
tartrate, phosphate, combination
use ____ tsp baking powder per ___ cup flour
1 1/2 tsp baking powder per 1 cup flour
old baking powder becomes more alkaline causing loss of _______ in baked goods
thiamin
_____ keeps yeast from sticking in baked flour mixtures
salt
_____ provides stability, retains leavening agent, distributes shortening by emulsification, introduces air, adds color and flavor in baked flour mixtures
egg
____ adds tenderness by coating gluten products particles in baked flour mixtures
fat
______ is hydroscopic, it modifies texture by tenderizing, and it softens gluten and prevents gluten development by absorbing some of the water that gluten needs
sugar
too much sugar in a flour mixture results in
coarse cells, thick walls, a shiny crust and a crumbly product
most of the sugar in honey is ____ and _____
glucose and fructose
term used to distribute fat into dry ingredients
cut-in
method of mixing used in foams- a down, across, up and across the top motion while rotating bowl
fold
_______ are leavened with steam, air, chemical leavening agents
ex: muffins, biscuits, popovers
quick breads
2 basic ingredients in quick breads are
egg and flour
excess mixing causes what
loss of carbon dioxide, tunnels from top to bottom, tough and heavy product
characteristics of a good muffin
round
pebbled top
pymmetrical shape
no long, narrow tunnels
method of mixing cake
cream fat with sugar, add egg, add sifted dry ingredients in portions, alternating with portions of milk
2 types of cakes
shortened cake (layer, pound cake, etc.) foam cake (angel cake)
shortened cake uses _____ as leavening agent, while foam cake uses ____ as leavening agent
chemical leavening; air
shortened cakes: layer cake uses \_\_\_\_\_ pound cake uses \_\_\_\_ and \_\_\_\_\_ rich cakes uses increased \_\_\_, \_\_\_, \_\_\_ gold cake uses egg \_\_\_\_\_ white cake uses egg \_\_\_\_\_ yellow cake uses \_\_\_\_\_ \_\_\_\_\_
baking soda air and steam fat, sugar, egg yolks whites whole egg
foam cakes:
angel cake: ___ ___ foam
sponge cake: ____ foam and ____ foam
chiffon cake: ____, ____, ____ and ____
egg white foam
yolk foam and white foam
liquid yolks, egg white foam, baking powder, oil
in cake, the more _____ the more time is needed to reach the elevated coagulation temperature of the gluten
sugar
*as sugar increases, the volume of cake increases up to the point where the volume is so great, and the gluten so weak, that the gluten stands snap and the cake falls in the center (gummy, crystalline appearance)
yellowing of cake is caused by
alkaline batter (excess baking soda)
fallen center of cake may be caused by
excess sugar, excess fat, excess baking powder, inadequate mixing, oven temp too low, open door during early baking
tough, dry crumb of cake is caused by
too much flour or egg, too much mixing, too little fat or sugar, over-baking
coarse texture in cake is caused by
too much baking powder or sugar, oven temperature to low, inadequate mixing
poor volume in cake is caused by
too little baking powder, improper level of sugar or fat
cookies are a modified shortened cake, which are higher in ___ and lower in ____ and ____
higher in fat
lower in sugar and liquid
pastries involve ____, ____, ____ and ____
flour, fat, liquid and salt
lard and oil are ___% fat, butter is ___% fat
100%; 80%
*when substituting butter for lard, need to use more
how is the tenderness in pie crust enhanced
by using oil, soft fats, or fat cut into very small pieces
how is flakiness of a pastry promoted
by leavening fat in coarse particles. Fat in pieces melts and flows, leaving a hole where steam collects and pushes upward against the upper surface of the resulting cell. the cell is locked into that extended position, resulting in a flaky crust
proportion of liquid to flour parts in the following: pour batter (ex. waffles) drop batter (ex. muffins) soft dough (bread) stiff dough (ex. pie crust)
liquid to flour
1: 1
1: 2
1: 3
1: 4
Use high protein bread flour in __________
yeast dough (low protein flour causes crumbly products with poor texture)
what does yeast do
ferments sugar and releases carbon dioxide
which method of preparing dough involves all ingredients being added before dough is allowed to rise
straight dough method
which method of preparing dough involves combining liquid with yeast and part of flour and allow this batter (sponge) to ferment for several hours; add sugar, salt, fat, rest of flour; knead
sponge dough method
which method of preparing dough:
- reduces processing time
- not as affected by fermentation time and temp
- commercial process that substitutes intense mechanical energy to a large degree for traditional bulk fermentation
continuous bread-making method
what is the final rising of the dough (fermentation) called
proofing time
- shortened in sponge method
- use strong flour, high in protein (bread flour)
when baking at high altitudes, you may have to decrease amount of ________ and increase amount of _______
baking powder, liquid
starch is compose of _____ and _____
amylose and amylopectin molecules
______ is responsible for gelation in cooled, cooked pastes
amylose
corn, rice and sorghum have only ______
amylopectin
- non-gelling; stable to freezing and thawing
- used in frozen foods
place the following starches in order of the effectiveness of thickening ability:
wheat, waxy rice, tapioca, waxy sorghum, potato, waxy corn
potato (best thickener), waxy corn, waxy rice, waxy sorghum, tapioca, wheat
wheat _____ is even less effective than pure wheat ______ because of the protein content
flour; starch
pastry and cake flour have more starch and less gluten, so they thicken (better or worse)
better
________ is the swelling that occurs when starch is heated in water close to the boiling point
gelatinization
*heat dissociates bonds, water moves in and swells granules
during gelatinization, sugar increases ________ and reduces _____ and ______
translucency; viscosity; gel strength
what happens if lemon juice (acid) is added to lemon meringue pie before cooking is complete and why
filling will be runny because acid breaks down starch and will give a runny product
what occurs in starches with a high proportion of amylose and is undesirable (reduced quality)
retrogradation (recrystallization)
-gives a gritty texture
what white sauce is half fat, half flour made by first melting the fat and adding flour
roux
to get a clear, shiny, translucent sauce, use ______ as thickener
cornstarch
name 3 crystal inhibitors (in crystallization)
acid (cream of tartar, vinegar)
fat (chocolate, milk)
protein (milk, egg whites, gelation)
overrun ice cream is the increase in volume from ______ and ______
freezing and whipping
how does fat interfere with crystal formation
it makes crystals small and smooth
*to make smoother ice cream, increase fat
gelatin
___ calories per gram
incomplete protein with no _____, and low ____ and ____
4 kcal/g
no tryptophan
low in methionine and lysine
an enzyme in fresh or frozen pineapple the breaks down protein and prevents gelation
bromelain
for best flavor, coffee should be brewed at ____ F
185-203 F
*at high temps, tannin is extracted and coffee is bitter
the FDA controls ______
additives (emulsifiers, humectant, stabilizers, anti-caking, nitrates etc.)
monoglycerides
diglycerides
lecithin
disodium phosphate
all examples of what
emulsifiers
gylcerol monostearate is what
humectant - retains h20
propionate is what
preservative; mold inhibitor
______ foods provide more benefits than the basic nutritional benefits
functional foods
functional food that reduces total and LDL cholesterol; found in fortified margarines
plant sterols and stanol esters
functional food that is found in grape juice and red wine; reduces platelet aggregation
resveratrol
functional food that is found in tomatoes; may reduce prostate cancer
lycopene
biologically active, naturally occurring chemical components in plant foods, act as natural defense for the plant - these are called what
phytochemicals
example of a phytochemical; from the cruciferous vegetables; detoxification of carcinogens
thiols
the additive influence of foods and constituents which, when eaten, have a beneficial effect on health
food synergy
