Food Science and Nutrient Composition of Foods Flashcards
F/v crispness
D/t osmotic pressure of water-filled vacuoles
Ripening and storage f/v
ethylene gas accelerates ripening of fruits during storage
F/v principles of preparation and processing
berries and mushrooms should be washed just before serving
Pigments: chlorophyll
GREEN
olive green in acid- pheophytin
bright green in alkaline- chlorophyllin (mushy, hemicellulose broken down)
Pigments: carotenoids
YELLOW ORANGE
little effet in acid or alkaline solution
lycopenes contribute to red color in tomatoes and watermelon and overtones in apricosts (act as an antioxidant, phytochemical)
Grading canned fruits and vegetables
USDA
A- desserts, salads (fancy)
B- processed (Choice)
C- puddings, pies (Standard)
Fresh produce: Fancy Extra #1 #1 Combination #2
F/v cooking methods
Frozen- shorter cooking time than fresh because blanching and freezing have made them tender
cabbage: to minimize the development of a strong flavor, cook for a short time, keep lide off initially to let acids escape cook in large amounts of water
10 Can f/v
per case: 6
wt: 6 lb 9 oz
measure: 13 cups
# servings: 20-25
Meat/poultry/fish structure and composition
sheet of connective tissue holds fibers in bundles
collagen: structural part of tendon that surrounds the muscle
in heat- hydrolyzed to gelatin, becomes tender
elastin: resistant to heat- little change in cooking
Meat/poultry/fish Nutritive value
Vit/min: thiamin, niacin, riboflavin, iron, copper, trace minerals
Pork is a good source of thiamin
Calcium content high in fish canned w/ bones, oysters, shrimp
Meat/poultry/fish pigments
Myoglobin + oxygen= red, brown, green
green color are due to further myoglobin breakdown
Meat/poultry/fish post mortem changes and aging
vacuum-packing meat in oxygen-permeable film, stored unfrozen at 0c is anaerobic (sous vide)- extends storage life of meat
Meat/poultry/fish inspection and grading
USDA done AT slaughter Grading indicates quality: Prime Choice Select Standard
Grading based on maturity of animal, marbling of fat, color and texture of lean
Meat/poultry/fish cookery principles
safe minimum internal temps:
145 F: pork, beef, veal, lamb, steaks, roast, fish
(155 F: ground meat and ground seafood)
160 F: ground beef, ground veal, ground lamb
165 F: turkey, chicken, duck
cured meats are pink from nitrites
Meat/poultry/fish methods of cooking determined by cut of meat
DRY: frying, broiling, roasting, grilling
MOIST: simmer, steam, stew
Roasting: when meat is removed from oven “carry over cooking” occurs for about 10 min, internal meat temp rises 15-25 F
Fish cookery
fresh fish with head attached should have bright red gills and bright, shiny skin, if gills are dull and gray reject it
Eggs
Yolk more concentrated than white, more protein (by wt), fat, minerals, vitamins
color of yolk depends on amount and type of pigment in hen’s diet
Egg quality
grading: candling, pass an egg in front of bright light to view contents
judge thickness of white location and condition of of yolk
Egg leavening
an acid stiffens an egg white foam by tenderizing the protein and allowing it to extend more easily
Egg whites at foam temp whip more quickly and yield a larger volume due to a LOWER surface tension
Custards
the larger the % sag the more tender the gel (objective measure of quality)
custards made from dehydrated eggs may be grayer and less yellow have an eggy flavor and be watery
Egg substitutes
when cooking with egg substitutes there will be color (added carotenoid) and flavor differences
Egg storage
loss of carbon dioxide makes eggs more alkaline
Fermented milks
Cultured buttermilk: add lactic acid bacteria to skimmed or partly skimmed milk, when using buttermilk in place of regular milk in a recipe need to increase the baking soda
Sweet acidophilus milk: skim milk plus acidophilus bacteria which reduces lactose
Use of milk in food preparation
When milk is heated, whey protein precipitates out on bottom of pan or on surface of milk
To prevent film from forming, cover or beat the milk to produce foam
To prevent milk from coating on sides of pan, heat over water
To prevent curdling, add an acid slowly and agitate (an acid precipitates casein)
Butter, cream
Butter 80% milk fat, margarine 80% veg oil or animal fat
At room temp, hydrolytic rancidity (uptake of water) leads to flavor changes in butter (saturated fat)
Unsaturated oils are more subject to oxidative rancidity (soybean oil) (uptake of oxygen at a double bond in an unsaturated fat)
Cream
Heavy or thick (>36% fat) Medium (30-36% fat) Whipped cream (35% fat) light or thin (18-30% fat) sour cream (>18% fat) half and half (no less than 10.5% fat)
Cheese
Processed cheese is a blend of several natural cheeses with an added emulsifier (disodium phosphate) better for cooking
high moisture content 41-50%
Grains and Cereals
quick cooking cereals have disodium phosphate added
makes cereal alkaline so particles swell faster
avoid on low sodium diets
Wheat flours
Graham, whole wheat: spoils quickly due to fat in germ
Bread (hard wheat): strong gluten, 11.8% protein
All-purpose (hard & soft wheat): less gluten, 10.5% protein
Pastry (soft wheat): weaker gluten, 7.9% protein
Cake (soft wheat): least and weakest gluten, 7.5% protein
Enriches with thiamin, riboflavin, niacin, iron, folic acid
Rice cookery
Cook in an amount of water that will be absorbed during cooking
Baked flour mixtures
Adding bran decreases the volume of end product, increase flour and liquid to compensate
Old baking powder is more alkaline causing loss of thiamin in baked goods
Sugar
hygroscopic- modifies texture by tenderizing
Quick breads
Basic ingredients: egg and flour
Excess mixing:
loss of carbon dioxide, overdeveloped gluten
tunnels from top to bottom, tough, heavy product
Cakes
Rick cake: increased fat, sugar, egg, increases keeping quality
Causes of variation in cakes
1) Yellowing: alkaline batter (excess soda)
2) Fallen center: excess sugar, excess fat, excess baking powder, inadequate mixing, oven temp too love, open door during early baking
3) Tough, dry crumb: too much flour or egg, too much mixing, too little fat or sugar, over-baking
4) Coarse texture: too much baking powder or sugar, oven temp too low, inadequate mixing
5) Poor volume: too little baking powder, improper level of sugar
Pastry
Flour, fat, liquid, salt
Lard and oil are each 100% fat, butter and margarine are only 80% fat so when subbing butter for lard, need to use more
Tenderness in a pie crust is enhanced by using oil, soft fats, or fat cut into very small pieces
Flakiness is promoted by leaving 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
Yeast dough
Proofing time: final rising of the dough, use strong flour, high in protein
Continuous bread-making method: 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
Starch
Thickening ability (most to least): potato, waxy corn, waxy rice, waxy sorghum, tapioca, wheat
White sauces
To get a clear, shiny, translucent sauce, use cornstarch as thickener
Frozen desserts
Overrun: the increase in volume from freezing and whipping determined by weight, should be 70-80%
To produce smoother ice cream, increase fat
Mellorine: imitation ice cream
Gel formation
bromelain is an enzyme in fresh or frozen pineapple that breask down protein and prevents gelation (inactivated at heat 170-180F)
Papain is a proteolytic enzyme from papaya that will prevent gelation
Coffee
Brew at 185-203F for best flavor
Additives (controlled by FDA)
1) Emulsifiers: monoglycerides, diglycerides, lecithin, disodium phosphate
2) sorbitol: humectant (retains moisture), sweetener, builking agent, limits mold
3) stabilizers/thickeners: pectin, cellulose, gelation, gum, agar (carrageenan prevents chocolate from sedimenting in fat-free milk)
4) nitrites: fixes color, inhibits spores of clostridium botulinum
5) mold inhibitor: propionate, sodium benzoate (soda)
6) antioxidants: propyl gallate, BHA, BHT, ascorbic acid (prevents browning), alpha tocopherol
7) flavor enhancing: MSG
Functional foods
Modified: fortified, enriched, enhanced
fortified margarines contain plant sterols and stanol esters which reduce total and LDL cholesterol
Phytochemicals
Isoflavones: soybeans- lower elevated cholesterol
Food synergy
the additive influence of foods and constituents which, when eaten, have a beneficial effect on food
