exam 3 Flashcards
Phytochemicals
non nutritive components in plants considered to have positive health benefits (flavonoids, carotenoids, tocopherols)
vegetable pigments
responsible for color, evidence of functional food properties
carotinoids
fat soluble pigment that is a yellow-orange color
- carotenoids (alpha, beta, gamma): yellow-orange (carrots)(beta carotene converted to vitaminA in body)
- lycopene: red-orange (tomato)
- xanthophyll: yellow (pineapple)
flavonoid pigments
water soluble pigments, flavones
- betalains: purplish-red (beets)
- anthoxanthin: creamy to white (cauliflower)
- anthocyanin: red-blue (eggplant, radish)
cell wall
fibrous
- cellulose and hemicellulose
- pectin compounds and hemicellulose
- lignin
- vegetable gums
cellulose and hemicellulose
found in greater proportion in skin/peel, protective layer secretes waxy cutin (protects the plant)
pectin compounds and hemicellulose
found within ad between cell walls, give firmness and elasticity to plant tissue
lignin
made form polymers and phenolic alcohols, increase in concentration as plant matures
vegetable gums
polysaccharides that can absorb water, added to processed foods to increase viscosity
parenchyma cell
thin flexible cell walls, major food source of plant structure, carries out most of plant’s metabolism (photosynthesis, storage), contains cytoplasm and organelles
structure of parenchyma cell
- cytoplasm: sticky gel-like compound found within the cell wall
- plastids: surrounds and bathe the organelles
- compounds are responsible for plant’s starch content, color, water, volume, flavor
types of plastids
- chloroplasts: contain chlorophyll, provide green color of plants
- chromoplasts: contain carotene or xanthrophyll pigments, provide orange-yellow color of plants
- leucoplasts: location of starch storage and some water, major digestible portion of plant
vacuole
an organelle in parenchymal cell that stores water, anthocyanin (red-blue pigment), flavor compounds (sugar, salt, organic acids); responsible for turgor
turgor
term applied to describe the firmness of a cell based upon its water content
- relates to juiciness
- crunch or snap of raw vegetables
- heat or humidity can reduce turgor in plants
effect of heat on vegetables
changes occur
- texture: starch gelatinizes, cellulose softens, water is lost
- flavor: flavor rich components in organic acids, s-compounds, salts, volatile oils, carbohydrates and phenolic compounds
- odor: cruciferous and allium vegetables are harsh
- color: affect pH, heat and metals
- nutrients: most are water soluble, use minimal water in preparation
effect of heat on texture
reduces bulk by water loss, increases tenderness (cellulose soften, digestibility does not change), heat vegetables until barely cooked (lignin not softened by heat: broccoli stems, end of asparagus)
effect of pH on heating vegetables
pH 4-4.5 retards softening (acidic foods), pectic substances are least soluble (resistant to softening), above or below this pH tissues will soften, adding baking soda over softens tissue and destroys nutrients
hard water
Ca or Mg; combines pectic substances to form insoluble complexes, interfere with softening, vegetables remain hard
enzymatic oxidative browning
oxygen reacts with natural iron content, acid containing ingredients will reduce browning (vinegar, lemon juice, orange juice)
phenolic compounds
tannins (unripe fruits) have bitter taste, astringent mouthfeel, degrades with ripening; found in abundance in apples, bananas, grapes, peaches, pears, and strawberries; responsible for enzymatic oxidative browning by activity of enzymes (phenols, catecholase, tyrosinase)
fruit respiration
respiration occurs as fruit grows, matures, and ripens; ethylene gas is a ripening hormone produced by fruit cells during maturation; unripe fruits may be stored in environment with ethylene gas to promote ripening
changes that occur as fruit ripens
- green color diminishes: carotenoid and flavone pigments develop
- flesh softens: changes in pectic substances
- acids develop: volatile and nonvolatile acids develop to create unique flavor
- organic acids decrease: sourness decreases, sweetness (monosaccharides) increases
purchasing fresh fruits and vegetables
USDA is responsible for voluntary producer quality grades from fresh fruits and vegetables; grades for fresh fruit are US fancy and US No. 1,2,3; based upon physical appearance (shape, color, ripeness, uniformity)
buying guide for fruits and vegetables
buy in season (flavor, nutrient content, cheaper), choose mature product (good appearance, no decay), buy for intended use, purchase by the pound, store at 36-40 degrees (tropical, subtropical: room temp) (roots, tubers: dry, constant temp)
frozen fruits and vegetables
freezing retains color/flavor, blanched before freezing (immersed in boiling water to inactivate enzymes), texture is reduced (ice formation, breaks cell walls, thawing results in softer texture)
frozen vegetables
popular, nutritious food choice when fresh vegetables are out of season or harvest date has long time prior to sale
canned fruits and vegetables
cooked and sealed for preservation, fruits are packed in sugar to preserve integrity of pieces
canned vegetables
thoroughly heated in water or 5% saline solution; thoroughly cooked, cannot withstand second cooking in kitchen; texture, nutritional value, and palatability are reduced if heated to 212 degrees
quality grades of canned/frozen fruits and vegetables
USDA voluntary grades, US grade A or fancy, US grade B or choice, US grade C or standard, US grade D or substandard
primary nutrients in vegetables
vitamin a, vitamin c, minerals, fiber, other vitamins
lycopen
give red color of tomatoes and other fruits, powerful antioxidant, high intake is associated with decreased risk of prostate and digestive tract cancers
luteolin
found highly in broccoli, celery, cabbage, spinach, green pepper, and cauliflower; has been associated with decreased growth cells and having anti-inflammatory growth
leaves
lettuce, cabbage, spinach, brussel sprouts; known for turgor (fiber content), vitamin a value, low in calories, high in oxalic acid (spinach varieties)
seeds
contain germ, cron, peas, green beans, lentils; known for high protein and fat content, high digestible carbohydrate content, high in calories
vegetable fruit
produced from the ripened ovaries of flowering plants, cucumber, eggplant, pumpkin, tomato, green pepper; variable in simple and complex digestible carbohydrate content, variable calorie content, high in water (92-94%)
flowers
broccoli, cauliflower, cruciferous; known for sulforaphane (phytochemical), high water content, low digestible carbohydrate content, low in calories
cruciferous vegetables
mild flavor (raw), strong flavor (cooked) due to decomposition of sulfur compounds in heating
stems
transport system of plant; celery, asparagus; known for structure, high in indigestible carbohydrate, high in water, low in calories
roots and tubers
storage of products from photosynthesis; potato, yam, sweet potato (tubers); carrots, beets, parsnip (roots); known for amylose, amylopectin content (starchy vegetable), high in calories
bulbs
grown underground, consists of layers of tissue; onion, garlic, leek, shallot; known for allylic sulfide content (phytochemical), moderate digestible carbohydrate content, moderate calories, slightly sweet
dietary sources of iron
heme iron food sources: meat, poultry, fish
non-heme iron food sources: tofu, dried beans, peas, lentils, whole grain pasta and bread, green leafy vegetables
types of connective tissue (collagen)
3 polypeptide strands arranged in a braid like 3D structure, white, tough and fibrous, soluble in hot water, responsible for increased tenderness when conversion is complete
types of connective tissue (elastin)
yellow, strong fibers used to support weight of body, heat and moisture have no effect, tenderized mechanically or chemically (grinding, marinading, swimming, cutting against the grain)
fat (adipose tissue)
layers under hide and around organs (subcutaneous and serve as stress cushion), cover fat (fat on outside of meat), intramuscular fat found within muscles (marbling), amount of fat in cut responsible for juiciness and flavor of meat
development and deposit of collagen
deposited throughout the body, increases with age and use (activity), greatest found in muscle groups used for movement (neck, shoulders, legs), tougher than muscle from loin or lower back areas that are used less
development and deposit of elastin
strong fibers, deposit along underside of body (brisket, short plate, flank)
fat terms
- larding: purpose to make dry meat juicy, insert long strips of cardoons through muscle
- piquing: same as larding but small strips
- barding: wrap cut with this slices of fat, any fat can be used
beef
produced primarily from steers and heifers of Angus or Hereford cattle, large 1000 lbs on hoof, 600 lbs trimmed, usually slaughtered between 30-42 months of age, red meat, hard fat (white to yellowish white), classified by age and sex
veal
young bovine, usually male offspring of milking cows, less than 3 months of age, light pink meat, very little fat, small muscle groups, little connective tissue, calf is 3-8 months
lamb
most imported from Australia or New Zealand, less than 14 months of age, dark red meat, high in fat, over 14 months is mutton, flavor strengths with age, tenderness decreases
pork
hogs or swine (barrow, gilt, sow, boar, stag), pigs are less than 4 months of age, hogs are 4 months or older, grey-pink meat, soft, greasy pink fat
cuts of beef
tender cuts of meat form less collagen (top of cow)
- tender: rib, short loin, sirloin
- less tender, still popular: chuck, round
- least tender: flank, short plate, brisket, foreshank
federal meat inspection act of 1906
mandatory inspection for wholesomeness of meat from domestic sources, imported meat subject to same standards, conducted by USDA (prior to slaughter, carcass, package materials, labeling)
quality grade
voluntary, most likely done since meat must be inspected, major factors are color of flesh, bone, grain of meat, texture, fat distribution/amount (finish, marbling)
yield grades
amount of lean meat on the carcass in proportion to fat, bone, and inedible parts, vary depending on range within each yield grade and the way carcass is cut, USDA grades 1 (highest) to 5 (lowest), pork is yield graded 1 to 4
dry heat methods of preparation
application of heat to meat without added moisture to denature or coagulate proteins, as heat is applied collagen unwinds to gelatin in the presence of moisture (tenderizing), muscle tissue becomes firm, cooking losses occur
moist heat methods of meat preparation
used for cuts that contain large amounts of collagen, water present in cut is insufficient to fully unwind collagen to gelatin, water is added to the recipe to facilitate conversion and the mixture is heated, cooking time increases
heating of meat
- coagulation of protein: 160-175F
- denaturation (moisture loss): 140F
- water lost
protein denaturation
heat applications cause gradual process
- visual changes occur between 122-149 degrees
- heme and other pigments remain pink
- meat is very juicy
- tender
- collagen begins to alter at rare stage
effect of temperatures on meat
- 100F: proteins begin to unfold, meat is red, soft, slippery
- 120F: proteins coagulate and lose water, meat is firm and pink
- 140F: connective tissue shrinks, moisture lost, meat is pinkish brown, loses juices
- 150F: connective tissue begins dissolving into gelatin-like substance, proteins densely packed, meat is brown and shrunken (starts to taste tough)
- 170F: proteins are entirely coagulated and most moisture is lost, meat tastes hard and dry
effect of heat on fat
melts fat (contributes to juiciness of meat), improved by basting (prevents surface evaporation of water
flavor development
heating develops flavor, alters amino acids, free fatty acids, carbonyl fractions improve aroma, flavor develops for first 3 hours of cooking then declines
protein hydrolysis
most important in moist heat applications; hydrolysis (hydrogen bonds break) of collagen to gelatin increase tenderness of meat, increase fragmentation of molecules to produce moisture loss through structural break down (meat falls apart)
