Food Science and Nutrient Composition of Foods (25%) Flashcards
what are the components of milk?
88% water, 5% CHO, 3.5% PRO, 3.3% FAT
________ is the chief CHO in milk
lactose
what does lactose breakdown into?
glucose + galactose
what percentage of milk protein is casein?
80%
what is the remaining protein in milk?
whey
what are milk precipitates that form in an acidic medium?
curd
what is whey? does it denature easily?
whey is the liquid that drains from the curd (coagulated milk used in cheese making)
yes. whey denatures easily causing the cooked flavor of milk
how many vitamins are needed for human nutrition that are present in milk?
all vitamins needed for human nutrition are present
what vitamin in milk is sensitive to ultraviolet light and needs to be protected
riboflavin (vitamin B2)
is milk a good source of vitamin C? explain.
no, d/t pasteurization process degrading vitamin C during the heating treatment
is milk a good source of iron?
no; however, research does not support milk consumption reducing/affecting iron absorbability. https://milk.procon.org/view.answers.php?questionID=000848
milk is the best source of ____________
calcium
list the types of milk products (7)
fluid milk, whole milk, UHT, filled milk, evaporated milk, sweetened condense milk, and dry milk
reduced fat (2%), low fat (1%), fat-free (skim)
fluid milk (labeled according to fat content)
not less than 3.25% milk fat and not less than 8.25% milk solids ( lactose, caseins, whey proteins, and minerals )
whole milk
what is the difference between pasteurization and homogenization?
pasteurization = the use of heat to kill disease causing microorgaisms in milk and increase milk safety homogenization = the use of high pressure which reduces the size of fat globules in milk to evenly distribute the fat and prevent separation of fat and liquid when packaged
uses a fat other than milk fat to create a substitute for milk (any milk, cream, or skim milk that has been reconstituted with fats, usually vegetable oils, from sources other than dairy cows)
filled milk
60% of the water is removed; must contain 6.5% butterfat and not less than 25% total milk solids
evaporated milk
15% sugar is added and volume is reduced to 1/3 of the original amount
sweetened condensed milk
usually made by removing 2/3 of the water from skim milk under a vacuum, then spraying this milk concentration into a chamber of hot filtered air; about 3% moisture content
dry milk
process of heating milk up and then quickly cooling it down to eliminate certain bacteria.
pasteurization
most commonly used method in the US; milk is pasteurized at 161°F (72°C) for 15 seconds; these conditions provide fresh tasting milk that meets the requirements for consumer safety.
HTST = High-Temperature-Short-Time Treatment
milk is pasteurized at 145°F (63°C) for 30 minutes
Hold or LTLT = Low-Temperature-Long-Time Treatment; less common practice
milk heated to 138°C and held for 2 seconds (kills all microorganisms); makes it possible to store milk in closed contaiers at room temperature for 6 months
UHT = ultra high temperature
any cheese made by clotting milk to form a curd and then concentrating the curd by draining the whey (containing no additives)
natural cheese
processed cheese w/ higher moisture content than processed cheese; 51% or more cheese, < 44% moistureExample: American cheese
processed cheese food
spreadable at 70 degrees, 44-60% moisture
processed cheese spread
less than 51% cheese and greater than 60% moisture
processed cheese product
soft, whitish in color and mild tasting, highly perishable, 80% moisture contentExample: cream cheese, cottage cheese, ricotta, marscapone
natural; fresh cheese
aged a short time, moisture content 50-70%Example: brie
natural; soft cheese
cheeses are 40-50% moistureExample: gouda, Edam
natural; semi-hard cheese
moisture content is 30-40%Example: cheddar, swiss
natural; hard cheese
cheeses are aged the longest and have approximately 30% moisture content
natural; very hard cheese
coagulation of milk w/ an acid
lowers the pH causing the casein to become insoluble and precipitate readily into curd.
milk products coagulated w/ an acid are lower in calcium than those coagulated w/ an enzyme example: milk w/ lemon juice as a substitute for buttermilk
coagulation of milk w/ an enzyme
most commonly used is rennin, which is used in the production of cheese and ice cream.
rennin clots are firmer than acid clots and more stable
coagulation of milk w/ heat
when milk is heated to near the boiling point, the whey proteins become insoluble, mesh with the milk’s calcium phosphate and precipitate forming a film (can burn easily)
coagulation of milk w/ casein
will not coagulate w/ heat unless it is boiled for long periods of time
coagulation of milk w/ polyphenolic compounds
found in some fruits, vegetables, teas, and coffees when combined w/ milk will result in the precipitation of proteins
they also contribute to the curdling of milk when making scalloped potatoes, tomato or asparagus soup
coagulation of milk w/ salt
when used in combination w/ milk can cause milk to curdle to prevent curdling salt or salted foods should be added to the milk base instead of milk being added to salt or salted foods
function of milk solids in ice cream
protein; contributes body and smoothness
function of sweetners in ice cream
flavor; corn syrup reduces ice crystals making for a smoother product
function of eggs in ice cream
delicate flavor; increases thickness and improves body; increases whipping ability
function of cream in ice cream
gives richness and smooth texture (mouth feel); reduces ice crystals
what factors interfere w/ or help reduce ice crystal aggregation (formation) in ice cream allowing for a smoother product
protein: gelatin, egg whites, milk powder fat: chocolate corn syrup
what are some examples of imitation ice cream
mellorine = a frozen dessert similar to ice cream but the milk fat has been replaced w/ vegetable fat (made w/ filled milk)
parevine = a product that has not butterfat or milk solids (sorbet - nondairy)
emulsifiers are added to natural cheeses, making them softer and easier to cook with; reduces spoilage potential; water added
processed cheese
known changes in eggs during prolonged storage
air cell increases in size
pH increases as egg ages d/t vitamin C loss
yolk membrane weakens
white becomes thinner
composition of egg/50 g
whole egg = 6 g PRO/212 g cholesterol/1 g CHO/75% water
white only = 4.2 g PRO/no cholesterol (0 g)/trace amounts of CHO/88% water; rich in B vitamins
composition of yolk
fat, fat soluble vitamins, cholesterol, iron , natural emulsifier
naturally occurring oil in water emulsion
egg yolk yields a stiffer, more stable emulsion than egg white b/c it has more protein (by weight)
lecithin helps yolk act as an emulsifier
lipoproteins stabilize the emulsion by interacting at the surface of the oil droplets to form a layer
what is the nutritive value of eggs
80 calories, 6 grams PRO, 5 grams FAT, vitamins A, D, riboflavin
yolk is more concentrated than white: has more protein (by weight), fat, minerals, vitmains
% composition of protein: egg white 11%, egg yolk 17.5%
comparison of egg substitutes and whole eggs
egg substitutes are egg whites w/ coloring, salt, no cholesterol or fatmore firm b/c fat is removed
comparison of egg protein and wheat protein
coagulation temperatures lower in egg (143 - 158°F)
similar in elasticity
quality of protein lower in wheat (only partially complete)
egg has ability to act as a leavening agent
cooking tips
green egg yolk = overcooked or slow to cool offiron (bluish gray color) from yolk combines w/ sulfur (yellowish color) = ferrous sulfide
green scrambled egg = overcooked, high temp steam table (too hot), egg reacts w/ metal serving utensil
how do you increase egg white foam?
use room temperature egg whites d/t LOWER surface tension
cream of tartar (acid) or an acid (lemon juice/vinegar) to denature protein (stiffens an egg white foam by tenderizing the protein and allowing it to expand more easily)
stabilize foam by adding sugar
*when an egg foam is heated, air expands, egg white stretchs and protein coagulates
what happens when you omit yolks in baking
egg yolk is a natural emulsifier (used to help stabilize foods and baked goods)
when removed, the properties of baked goods are changed
what has 0.4 g vs 0.1 g of an ordinary egg and how is done?
omega-3 eggs
achieved by feeding hens a diet of 10-20% flax seeds
what does the USDA inspection of meats mean and are they mandatory?
the animal was healthy at time of slaughter and sanitary conditions were used
inspection is mandatory
has nothing to do with the quality of meat 1997 regulation incorporates the HACCP guidelines along w/ mandatory E.coli testing
are USDA grading of meats mandatory or voluntary?
voluntary; paid by processor
purpose: for untrained consumer to buy quality
what are the grades of meat for each animal?
beef = prime, choice, selection, standard, commercial, utility, cutter, canner veal = prime, choice, good, standard, utility, culllamb = prime, choice, good, utility, cull pork = 1, 2, 3, 4, utility poultry & fish = A, B, C
__________ is chiefly responsible for the color of meat?
myoglobin; it is the iron-carrying compound in muscle
what red pigment in blood is removed during slaughter?
hemoglobin (hgb)
what is the oxygenated form of myoglobin that results in bright red color of meat?
oxymyoglobin
__________ is the brownish red form of myoglobin when ferrous iron is oxidized
metmyoglobin
what is the structure and composition of meat?
mainly comprised of muscle, connective tissue, fat and bone
muscle tissue is broken down by enzymes during aging process
connective tissues include = collagen, elastin, reticulin, and ground substance
what are extractives?
non-protein substances that help give meat its flavor; water-soluble
list dry heat cooking methods
broil, fry, roast, pan broil, grilling
why is frying considered a dry heat cooking method if it is being cooking in a liquid?
dry-heat cooking methods are those that utilize air or fat; fat is used in frying or deep frying
list moist heat cooking methods
stew, braise, poaching, steaming, simmering, en papillote
how does moist-heat cooking methods work?
uses water, liquid or steam to transfer heat to food
meat made from cuts that are inexpensive, made by cutting small particles, adding fat/and other ingredients and shaping into uniform portions
restructured meat
products made my pulverizing meats and adding fat and salts before heating and resulting mixture
comminuted meats
ex. hot dogs
list tender cuts of meat and the best method of cooking
rib cut, short loin cut, sirloin cut
rib cut = rib roast, rib steak, rib steak (boneless), rib eye (roast or steak)
short loin cut = top loin steak, t-bone steak, porterhouse steak, boneless top loin steak, tenderloin (filet mignon steak or roast - also from sirloin), new york strip steak
sirloin cut = pin bone sirloin, flat bone sirloin, wedge bone sirloin, boneless sirloin
*best method = dry heat; broil, panbroil, panfry, or roast (rib)
what % of fish is protein, its benefits and recommendation of consumption?
18-20%high quality protein, lower fat content (compared to meat), higher PUFA, and omega-3 fatty acids*recommendation = eat fish at least 2x/week
mollusks vs crustaceans
mollusks = shellfish w/ a protective shell; scallops, oysters, clams crustaceans = shellfish w/ a horny covering; shrimp, lobsters, crabs
what is the % of lean fish vs fatty fish? provide some examples
lean fish = < 5% fat fatty fish are > 5% fat, but not more than 10 g of fat
lean fish: bass, cod, flounder, haddock, halibut, pike, red snapper, sole, whiting
fatty fish: Butterfish, Herring, Lake Trout, Mackerel (Spanish, Atlantic), Ocean catfish, Salmon (king, Atlantic, sockeye, coho), Tuna, Whitefish
fish are usually _________. what % of collagen does fish have compared to average land animals?
tender fish have 3% collagen while an average land animal contains 15% collagen
the muscles of fish are not in long bundles but rather shorter and arranged in _________ layers of short fibers. they are also separated by thin sheets of connective tissue. what does this account for?
myotomes (segment or sheet of ms) flakiness of fish
describe fish muscles
gram for gram, fish have more muscle than any other vertebrate; a male salmon or tuna can be nearly 70% muscle, which is one reason why fish are so good to eat
each segment, or sheet, of muscles is called a myomere or myotome and is separated from its neighbor by a sheet of connective tissue
pigment of fish depends on?
whether the fish relied on quick or slow movements to survive
red or darker colored flesh fish had higher concentrations of “slow twitch fibers”
white flesh fish tend to have more “fast twitch fibers” = quick moving
list fish high in omega-3 fatty acids
more than 1 gram = Herring, Mackerel (Pacific, Jack, Spanish), Salmon (Atlantic, king, pink), Tuna (bluefin), Whitefish