Domain I-Topic A: Food Science and Nutrient Composition of Foods Flashcards
What is the crispness of vegetables (state of turgor) due to?
The osmotic pressure of water-filled vacuoles
What is the limiting amino acid in soybeans?
Methionine
What is the percentage of protein in protein concentrates and protein isolates?
> or equal to 70% and 90%
Soybeans are used in…?
Textured protein products
Chemical changes are due to…?
Enzymes
Protopectin (large,insoluble) is converted to _______ (ripe fruit) then converted to ________(overripe fruit)
Pectin; pectic acid
What accelerates ripening of fruits during storage?
Ethylene gas
Which fruits ripen best at room temperature?
Avocados
Bananas
Pears
Tomatoes
If apples are stored in a controlled atmosphere (reduced oxygen), does aging occur faster or is it delayed?
Delayed
When should mushrooms and berries be washed?
Just before serving
Fruits low in vitamin C from darken rapidly when cut due to enzymatic action. How can this be prevented?
- ) Dip in citrus juice
- ) Add sugar before freezing
- ) Heat to boil
Green pigment is due to…?
Chlorophyll…more like borophyll
Green pigments turn olive green in acid due to….?
Pheophytin
Green pigments turn ______ green in alkaline solution (like baking soda) due to…?
Bright; chlorophyllin (mushy; hemicellulose is broken down)
Yellow & orange pigments are the…?
Soluble or insoluble in water?
Little or large effect in acid or alkaline solution?
Carotenoids
Insoluble in water
Little effect
What contributes to the red color in tomatoes and watermelon, and overtones in apricots (act as antioxidants)?
Lycopenes
Flavinoids
Anthocyanins (red, blue & purple)
Anthoxanthins or flavones (white)
Flavinoids are soluble or insoluble in water?
Soluble
Anthocyanins turn ____ ____ in acid and _____ in alkaline.
Bright red; bluish
Anthoxanthins or flavones (white) are ________ in acid and _______ in alkaline.
Colorless; yellow
*Onions turn yellow in aluminum pan
Flavor of fruit is due to…?
acids, sugar and aromatic compounds
What causes an astringent feeling in the mouth? (*Found in underripe bananas)
Tannins
The grade of fruits/vegetables is based on what? (7)
Quality, firmness, color, maturity, freedom from defects, uniform size and shape
Canned Fruits & Vegetables
Grade A
desserts & salads (Fancy)
Canned Fruits & Vegetables
Grade B
Processed (Choice)
Canned Fruits & Vegetables
Grade C
Puddings & pies (Standard)
Fresh Produce Grades (5)
Fancy Extra #1 #1 Combination #2
Who grades fruits & vegetables?
USDA
What causes color changes in raw, peeled or bruised potatoes?
Phenolic compounds
What causes green color under the skin of potatoes?
Chlorophyll that develops when potato is exposed to light during storage.
May be accompanied by solanine, a natural toxicant.
Potatoes
Starch changes to ____ during storage.
sugar
How do old potatoes change in taste, color and texture?
Sweeter in taste
Cook to a darker brown (Maillard reaction)
Softer in texture
Cooking method: small amount of salted water for a short time, covered pan unless otherwise indicated.
Boil
Cooking method: perforated container, covered, over boiling water
Steam
retains color; flavor; cut small
Pressure cooking
Use tender vegetables, high in moisture; don’t drain
Stir-fry
Shorter cooking time than fresh because blanching and freezing have made them tender
Frozen
What is the suggested preparation method for cooking cabbage to minimize the development of a strong flavor?
Cook for a short time, keep lid off initially to let acids escape, cook in large amoint of water.
What # can measures 13 cups, 20-25 servings, and weighs 6 lbs. 9oz.?
10 can
What are the possible can sizes?
10 (13 C), #3 (5 3/4 C), #2 1/2 (3 1/2 C), #2 (2 1/2 C), #300 (1 3/4 C)
The muscle is composed of bundles of fibers called _______.
myofibrils
The structural part of tendon that surrounds muscle.
In heat, it’s hydrolyzed to gelatin and becomes tender.
Collagen
Resistant to heat- little change in cooking
Found in ligaments, cartilage; yellow color
Elastin
Amount of fat cover on carcass
Finish
What identifies the cut of the meat?
shape of the bone
Round bone- leg; T-bone- back and ribs
% protein in meat/fish/poultry
16-23%
CHO content in meat/fish/poultry
glycogen in liver; glucose in blood
Vit/mins in meat/fish/poultry
thiamin, niacin, riboflavin, iron, copper, trace minerals
Fabricated into simulated meat products.
MIxed with ground meats- extends number of servings, lowering costs.
Textured Vegetable Protein (TVP)
Main contributor to meat color
Myoglobin
Myoglobin + oxygen –> red–> brown–> grean
*green colors are due to further myoglobin breakdown (not harmful)
Change in muscle protein brought about by enzymes which increase the ____-_____ _____ of the muscle.
WATER-HOLDING CAPACITY
What 2 things also increase tenderness by increasing water-holding capacity of muscle?
Acid (vinegar) and salt
Vaccum-packing meat in an oxygen-impermeable film, stored, unfrozen at 0’F is aerobic or anaerobic?
ANAEROBIC (sous vide)- extends storage life of meat
Air is removed and replaced with gases (carbon dioxide, nitrogen)
MAP: Modified Atmosphere packaging
True or False: Meat inspection is mandatory.
True
Who conducts the inspections and grading of meat?
UDSA
When are meat inspections and grading done?
Time of slaughter
The act that assures consumer that the animal was healthy at the time of slaughter and the meat is fit for human consumption (assures wholesomeness). It’s shown with a round purple stamp “USDA Inspected and Passes.”
Wholesome Meat Act of 1967
What does grading indicate?
Quality
What are the possible grades of meat?
Prime *Most marbling
Choice
Select
Standard *Least marbling
What is grading based on?
Maturity of the animal
Marbling of fat
Color
Texture of lean
Where do the most tender cuts come from?
The least used muscles (loin, backbone).
*pork chops- loin
Where do the least tender meats come from?
The most used muscles (flank, brisket) .
* medium tender meats come from the shoulder (chuck)
Temperature for roasting
325’F
IMPS
NAMP
Institutional Meat Purchasing Specifications
National Association of Meat Purveyors
High temps INCREASE/DECREASE shrinkage (toughen)?
Increase shrinkage or toughen the meat
A slow-cooked roast yields MORE/LESS waste?
LESS waste
Insert meat thermometer BEFORE/AFTER cooking?
BEFORE
Safe minimum internal temperature for:
pork, beef veal lamb steak, roast, fish (meat & fish)
145’F
Safe minimum internal temperature for:
ground beef, ground veal, ground lamb (ground meat)
160’F
Safe minimum internal temperature for:
turkey, chicken, duck (poultry)
165’F
What happens to collagen when meat/poultry/fish is cooked?
Collagen is hydrolyzed to gelatin and softens.
What happens to meat when exposed to heat?
Color changes from red to pink to brown to grey. Heat denatures globin; iron is oxidized.
What can be added to meat to increase tenderness?
Vinegar- lowers pH and INCREASES water holding capacity of muscle.
Cured meats are pink from what?
Nitrates (inhibit botulism)
Forms of dry heat
Frying
Broiling
Roasting
What cuts are dry heat used for?
Tender cuts- near backbone (loin, sirloin)
What is a desirable property of fat used in frying?
A fat with a high smoke point (>400’F)
Cuts of meat that should not be fried
Tough cuts (bottom round)
What is moist heat used for?
Less tender cuts with more connective tissue (bottom round, chuck, brisket).
*Cook bottom round in water for several hours.
Types of moist heat
Braising Simmer Steam Stewing Proteolytic Enzyme (papain)
Braising means to-
Flour meat, brown, cover, simmer in liquid. Can be done in oven or on top of range.
Simmer means to-
heat in water to 170-185’F with appearance of bubbles.
Steam means to-
heat over, not in, water
Stewing means to-
add water or other liquid during cooking
What is proteolytic enzyme (papain)?
Blend of salt and papaya that tenderizes meat
What should fresh fish with head attached have?
Bright red gills and bright, shiny skin.
*If gills are dull and grey, reject it!
What is surimi?
purified and frozen minced fish with a preservative.
The yolk of an egg is surrounded by…?
vitelline membrane
Chalazae
yolk anchors- holds yolk in center
Egg yolk is a naturally occurring…
oil in water emulsion
Describe the nutritive value of an egg.
80 KCAL, 6 g PRO, 5 g FAT, vit A, D, riboflavin.
Yolk is more concentrated than whites- more PRO by weight, fat, vits & mins.
Percent composition of PRO in an egg (egg white vs. yolk)
egg white 11%, egg yolk 17.5%
What does the color of the yolk depend on?
Amount and type of pigment in hen’s diet
What does candling mean?
- To pass an egg in front of bright light to view contents.
- Judge thickness of white, location and condition of yolk
True or False: grading does NOT include the color of the shell, nor the size of the egg.
True
Grades of an egg include…
AA, A, B
Sizes of eggs are based on weight per dozen. What are the various size classifications? (6)
Jumbo (30 oz) Extra Large (27 oz) Large (24 oz) Medium (21 oz) Small (18 oz) Peewee (15 oz)
Eggs can be maintained for ___ months in cold storage (29-32’F) with Grade ___
6 months, Grade A
What happens when a fresh egg is placed in a pan of cold water? What happens with an old egg?
A fresh egg sinks; an old egg floats
Syneresis (weeping)
Liquid released from coagulated product
*occurs when cooked at too high a temperature, or too low a temperature for too long a time; creates a tough, watery product. (droplets of water on surface)
What does an acid do to an egg white foam and how?
Acid stiffens an egg white foam by tenderizing the protein and allowing it to extend more easily.
Egg white foams are compared by measuring what?
specific gravity
Egg whites at room temperature whip more quickly and yield a larger volume due to LOWER/HIGHER surface tension?
LOWER surface tension
What can also stabilize an egg white foam?
Sugar
How does protein in an egg stabilize an emulsion?
Protein forms a thin film around droplets of oil.
Why does egg yolk yield a stiffer, more stable emulsion than egg white?
It has MORE protein (by weight)
What helps yolk act as an emulsifier?
Lecithin
How do lipoproteins stabilize the emulsion?
By interacting at the surface of the oil droplets to form a layer.
* Mayo is an example of a food emulsion stabilized by egg yolk.
When does the surface of yolks turn green and why?
- When overcooked or allowed to cool slowly
- Due to a combo of iron from the yolk and sulfur from the whole egg– creates ferrous sulfide.
What are baker’s special eggs?
sucrose is added to improve foaming ability
Egg substitutes will often be HIGHER/LOWER in sodium?
HIGHER
When cooking with egg substitutes, what differences will be present?
color and flavor difference
When eggs are held in the refrigerator too long, there is a loss of carbon dioxide, which makes the eggs more ALKALINE/ACIDIC?
ALKALINE (add more acid)
Milk composition: % water % FAT % CHO (lactose) % PRO (complete, HBV)
87% water
- 7% FAT
- 9% CHO (lactose)
- 5% PRO
Milk is 80% ______, which is precipitated at a pH of 4.6 and forms sift curd.
Casein
The liquid that drains from curd of clotted milk
Whey
Name the components of whey (5)
Lactose Lactalbumin Lactoglobulin Water soluble vitamins MInerals
Milk and milk products are a good source of… (5). They are low in…. (1).
Good source of calcium, phosphorus, riboflavin, vitamins A and D.
Low in iron.
Temps/times for pasteurization (to destroy pathogenic bacteria)
145’F for 30 minutes or 160’F for 15 seconds
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)
Types of Milk
1.5-2.25% fat
2% milk
Types of Milk
0.5-2% fat
Low fat milk
Types of Milk
<0.5% fat
Skim milk
Concentrated milks (4)
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)
Fermented milks include…(3)
Cultured buttermilk
Sweet acidophilus
Kefir
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
Yogurt
When milk is heated, what happens to they why 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
BUTTER/MARGARINE turns rancid as it takes up oxygen an releases hydrogen.
BUTTER
Types of cream
heavy or thick medium whipped cream light or thin sour cream half and half
Creams with 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
Types of cheese (3)
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.
Grains and cereals
Part of endosperm, separated with bran
aleurone layer
Grains and cereals
In germ, has most of thiamin
Scutellum
Inner portion of wheat kernel
Farina
Quick-cooking cereals have ____ ____ added.
Disodium phosphate
- makes cereal alkaline so particles sweel faster
- Should be avoided on low sodium diet
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?
Made from gliadin and glutenin through process of hydration and mixing.
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?
“Bleached”
Natural agents cause oxidation and turn flour from creamy yellow to white.
What does the strength of the flour refer to?
the capacity to retain leavening
- depends on quality of gluten (bread flour- strong, cake flour- weak)
Adding bran INCREASES/DECREASES volume of end product?
DECREASES
Increase flour and liquid to compensate
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 soda provides…
A dry acid…
Cornstarch…
Baking Powder
- Baking soda provides carbon dioxide
- A dry acid reacts with soda to release carbon dioxide
- Cornstarch keeps contents dry
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
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. 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 ____ & _____.
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
*carbon dioxide is released at a faster rate than fermentation
Basic ingredients in quick breads include: (2)
Egg and flour
Excess mixing causes…
(1) loss of carbon dioxide
(2) tunnels from top to bottom
(3) Tough, heavy product
Characteristics of a good muffin
Round
Pebbled top
Symmetrical 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
Types of cakes
Shortened cake (layer, pound cake, etc.) Foam cake (angel cake)
Shortened cake uses _____ as leavening agent.
Foam cake uses ____ as leavening agent.
Chemical leavening; air
Shortened cakes: Layer cake uses \_\_\_\_\_. Pound cake uses \_\_\_\_ & \_\_\_\_\_. 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 cake:
Angel cake: ___ ___ foam
Sponge cake: ____ foam & ____ foam
Chiffon cake: ____, ____, ____ & ____
egg white foam
yolk foam & 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 caused by…
alkaline batter (excess soda)
Fallen center of cake 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 caused by…
Too much flour or egg, too much mixing, too little fat or sugar, over-baking
Course texture in cake caused by….
Too much baking powder or sugar, oven temperature to low, inadequate mixing
Poor volume in cake 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, buttter 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 & 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
Method of preparing dough:
All ingredients are added before dough is allowed to rise
straight dough method
Method of preparing dough:
Combine 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 method
The final rising of the dough (fermentation).
Proofing time
- Shortened in sponge method
- Use strong flour, high in protein (bread flour)
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
When baking at high altitudes, may have to decrease amount of ____ ____ and increase amount of _______ to.
baking powder; liquid
Starch is compose of _____ & _____.
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/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? Why?
Filling will be runny because acid breaks down starch and will give a runny product.
Staling of starch products.
Occurs in starches with a high proportion of AMYLOSE.
Undesirable (reduces quality)
Retrogradation (recrystallization)
-gives a gritty texture
Melt fat, add flour (half fat, half flour)
Roux
To get a clear, shiny, translucent sauce, use ______ as thickener.
cornstarch
Crystal inhibitors include: (3)
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.
Bromelin
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, hermectant, stabilizers, anti-caking, nitrates etc.)
Monoglycerides
Diglycerides
Lecithin
Disodium phosphate
Emulsifiers
Gylcerol monostearate
Humectant (retains H2O)
Propionate
Preservative; mold inhibitor
______ foods provide more benefits than the basic nutritional benefits.
Functional foods
Functional food; reduce total and LDL cholesterol; found in fortified margarines.
plant sterols and stanol esters
Functional food; found in grape juice and red wine; reduces platlet aggregation
resveratrol
Functional food; found in tomatoes; may reduce prostate cancer
lycopene
Biologically active, naturally occurring chemical components in plant foods, act as natural defense for the plant
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
