Help
Options
Didn't know it?
click below
click below
Knew it?
click below
click below
Don't Know
Remaining cards (0)
Know
retry
shuffle
restart
0:00
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.
Normal Size Small Size show me how
Normal Size Small Size show me how
FCS 309 EXAM 2
| Question | Answer |
|---|---|
| What is milk primarily composed of? | 90% water! |
| What determines the specific milk composition? | cow species, point in production process, etc. |
| What is the primary carbohydrate in milk? | lactose |
| Where else is lactose found? | mostly milk products; rather uncommon |
| How is lactose to work with? | difficult; hard to dissolve & keep in a solution leading to crystallization and sandy textures |
| What are the two basic milk proteins? Percentages of both? | casein (80%) and whey (20%) |
| Casein | milk protein; insoluble; precipitates with low pH to form curd; molecules form micelles that can aggregate to form a gel |
| Whey | milk protein; liquid; can be observed when cutting into a curd of casein; very sensitive to heat |
| Which type of marconutrient varies the most in milk? | fat content |
| What lipids are in milk? | triglycerides; dispersed as fat globules to form a membrane (lipoproteins embedded in the membrane) |
| What part of milk acts as an emulsifying agent? | lipoproteins in the fat-globule (triglyceride) membrane |
| What two vitamins/minerals is milk NOT a good source of? | iron and vitamin C |
| What are some vitamins and minerals commonly found in milk? | riboflavin, calcium, phosphorus, thiamin, niacin, vitamin A and Vitamin D (added to most milk) |
| What factors can affect the flavor of milk (6)? | volatile compounds, sunlight, cattle feed, heating, fermentation, storage method |
| Name three types of volatile compounds | aldehydes, ketones, & acids |
| What is rbST stand for? | Recombinant Bovine Somatotropin |
| What is rbST's role in milk production? | injected into cattle to increase milk production (helps make up to 1800 more lbs of milk per cow each year); no known human health issues; does not alter the milk composition |
| What does rbST do to milk composition? | NOTHING; does not alter it at all |
| What are 5 types of processing that can be done to milk? | pasteurization, homogenization, evaporation, drying, and fermentation |
| Pasteurization | heat treatment to kill microorganisms; majority of milk is pasteurized; helps decrease food illness |
| 3 methods of pasteurization? | hold method, HTST method, UHT pasteurization |
| Hold method | pasteurization of milk heated to a moderate temperature and held for a longer period of time |
| High Temperature Short Time method | pasteurization of milk done for a short time at a high temp; most common today |
| Ultra-High Temperature method | super high temperature held for about 2 seconds before letting it cool; does not have to be refridgerated after pasteurized until its been opens; good fro transporting |
| Raw milk | no pasteurization; microorganisms can cause illness in it |
| Homogenization | splits and disperses fat globules throughout milk such as creaming; produces the white appearance of milk; makes milk flavor less prominent |
| "Creaming" | naturally, fat globules in milk become clusters and rise to the top, separating the cream from the aqueous portion |
| Evaporated milk | canned milk that has water evaporated from it to half its volume yet double the concentration of protein and fat |
| Sweetened condensed milk | sugar added to milk before evaporation |
| What is the purpose of drying milk? | stored longer, no refrigeration needed, and easy to transport |
| Instantized dried milk | dried, the moistened until sticky, then re-dried; they do this to prevent lumping when rehydrated |
| Fermentation | microorganisms used to ferment lactose to lactic acid |
| What types of things are made via fermentation? | buttermilk and yogurt and kefir |
| What's the problem with fermentation? | its a good condition for all microorganisms to grow so careful sanitation is needed |
| What are the 6 general categories of milk products? | milks, butter, creams, cheeses, ice creams, frozen desserts |
| How is milk categorized? | by fat content |
| Lower fat content of milk leads to ___________ nutrient content. | higher |
| Lactaid | reduced lactose content |
| Can lactose-intolerant people consume fermented products? | usually! |
| Is soymilk dairy? | nope--doesn't come from a cow |
| What type of emulsion is butter? | water-in-oil (15% water, 80% fat) |
| What gives butter its yellow color? | annatto |
| What are the differences in fat content between half-and-half and heavy whipping cream? | half/half: 10.5% heavy whipping: 36% |
| How are natural cheeses generally formed? | curd formation, cut the curd, drain the whey |
| What is a processed cheese? | natural cheese + heat and an emulsifying agent |
| What percentages of milk fat & milk solids are ice creams (plain)? | 10% fat, 20% solids |
| What percentages of milk fat & milk solids are ice creams (composite)? | 8% fa, 18% solids |
| what makes frozen custards different from ice creams? | addition of egg yolks |
| What percentages of milk fat & milk solids are ice creams (low-fat)? | 2-7% fat, 11% solids |
| What percentages of milk fat & milk solids are ice creams (sherbet)? | NO FAT; 2-5% milk solids |
| Mellorine | milk fat is replaced by less saturated fats |
| Parevine | no fat or solids |
| What happens to whey proteins with the addition of heat? | denaturation, thin layer of precipitate on the bottom of the pan |
| Scorching | protein at the bottom interacted with lactose to produced undesirable browning |
| Scum | denatured protein molecules form together |
| What is acid's effect on milk? | may cause curdling; frequent stirring can help |
| What is salts effect on milk? | some denaturation and coagulation due to conflicting electrical charges |
| Are changes in heated cheeses reversible? | nope |
| What can happen when you heat natural cheeses? | stringiness, toughness, & fat separation |
| What two components allow cheeses to be heated with ease? | moisture and high fat content |
| What are two types of foams? | milk & cream foams |
| Milk foams | protein and water in milk are extended in thin films with agitation; thin films enclose small air bubbles |
| What are the ideal conditions for making a milk/cream foam? | cold, slightly old, additions of stabilizers, high protein (& fat) |
| Cream foams | fat content of at least 30%; must keep whipped cream refrigerated until use |
| Can fluid milks create foams? | nope, not enough protein |
| What can be whipped into a great large foam? Why? | evaporated milk due to high fat/protein concentration |
| Proteins in milk have ____ surface tension & vapor pressure. | LOW |
| When does the egg shell form? | as it moves down the oviduct |
| Eggshell composition | outer coating, calcium; pores to allow passage of gases |
| Bloom (eggs) | when laid, has a coating that protects from microorganisms |
| Calaza | strings that hold egg yolk in place |
| Albumin | white of the egg |
| Air cell | only forms after the egg is laid and as it cools; increases with age |
| Egg white composition | more protein, 90% water |
| Egg yolk composition | 1/3 lipids, cholesterol, more calories, vitamin A, iron |
| What can denature the proteins in egg whites? | heat! |
| Avidin | protein in egg white that is able to bind biotin before it is denatured and was used in research to discover biotin uses in the body |
| Phosvitin | yolk protein that binds iron which causes the yolk to contain a wee bit of iron |
| Omega-3 Eggs | hens are fed a diet with flaxseed to increase omega-3 in the eggs —benefits: nutritional benefits —downfalls: more expensive |
| Cage-free eggs | hens are not in a metal cage, but could still be in a barn |
| Free-range eggs | hens may be outside during the day |
| What is the nutritional benefit of cage-free/free-range eggs? | NONE! |
| Candling | checking egg quality IN THE SHELL; look for yolk centered with little movement |
| What 3 things happen to eggs with long-term storage? | quality declines, air cell grows, and alkalinity increases |
| How can egg quality be measured out-of-shell (3)? | Haugh units, albumen index, & yolk index |
| Yolk index | egg quality by measuring height; out of shell |
| Albumen index | egg quality by observing the spread of the white; out of shell |
| Haugh units | egg quality by comparing height to weight; out of shell |
| Salmonella enteritidis & eggs | infects when the egg is forming; its inside the egg |
| Temperature for non-cooked egg safety | 71C |
| Cooked egg temperature ofr safety | 60C |
| Three ways of preserving eggs? | pasteurization, drying, and freezing |
| Challenge with pasteurization of eggs? | heating just enough to kill microorganisms without altering the egg proteins —eggs sold without shells mean they could be exposed to more things |
| Drying eggs: why & examples of products? | why: long term storage products: whole egg solids, yolk solids, fortified whole egg solids |
| Spray-dried eggs | may affect whipping characteristics, color, & flavor —glucose in the eggs can start to react with the yolk when stored long term that can affect the flavor |
| Freezing of egg whites vs. egg yolk | Whites: freeze well Yolks: form a gel; add 10% salt or sugar to prevent this |
| What are the 4 applications/uses for eggs? | coloring agent, emulsifying agent, thickening agent, and ??? |
| What types of pigments are in eggs? | carotenoid |
| What two things are in eggs that help as an emulsifying agent? | lecithin & lysolecthin |
| What type of emulsion are eggs? | oil-in-water |
| How can eggs be thickening agents? | —heating leads to denaturation/coagulation that aids in thickening —you need to increase the temperature of cooking when sugar is added (e.g. cooking custards to higher temperature than just a simple fried egg) |
| Custards | sweetened egg mixtures thickened with egg and flavored with salt and vanilla |
| Stirred vs. baked custard | —stirred: agitation causes a sol —baked: no agitation causes a gel |
| Cooked salad dressings/sauces | —egg is the thickening agent —pros: lower fat & calorie content |
| Cream pies & puddings | thickened by egg protein and starch, though soft gel rather than sol |
| Ferrous sulfide | green ring when egg is cooked too long or too slowly |
| How should hard-cooked eggs be made? | cover the eggs with room temperature water then heat to boiling and let them sit for 15-17 minutes to help prevent FERROUS SULFIDE |
| Poached egg | white coagulated around the yolk |
| Scrambled eggs | added liquid (e.g. milk) increases tenderness; beat the mix to combine yolk/milk completely so there aren’t streaks of various colors |
| Yolk foams | heavy foam, stable; used for fluffy omelettes, souffles; not as high volume |
| White foams | stable, voluminous, used for meringues, sponge cakes, angel food cake, etc. |
| What two factors add to a stable, high volume egg foam? | low surface tension and low vapor pressure |
| How is the stability of a foam judged? | by measuring drainage of liquid |
| What two things increase stability of an egg white foam? Decrease? | Increase: sugar & acid Decrease: extra liquid & yolk contamination |
| What things increase egg white foam volume? Decrease? | Increase: water, temperature, white quality, wire whisk, sugar Decrease: overbeating, acid, salt, and yolk contamination |
| What two characteristics are important when observing egg foams? | stability and volume |
| Meringues | egg white foams containing sugar |
| Difference between hard meringue & soft meringue? | HARD MERINGUE: sugar increases the beating time by a lot; stiff peak baked at a low temperature SOFT MERINGUE: about half the amount of sugar; delicate; lemon meringue pie |
| Leaking of meringues | liquid draining due to failure of protein coagulation —place on still hot filling and bake to help prevent this |
| Beading of meringues | amber-color droplets on surface of overbaked soft meringues —quick heating can help |
| Positives (2) and Negatives (3) of egg substitutes? | PROS: lower cholesterol, replacement in many recipes CONS: lower volume, poor aroma/flavor, cannot replace in sponge or angel food cakes |
| Amino acids | organic compounds containing an amino group and an organic acid (carboxyl) group |
| Carboxyl group | organic acid group such as on an amino acid |
| Proteins | composed of many amino acids joined together by peptide linkages |
| What makes each amino acid unique? | its R group |
| Peptide linkage | linkage from the nitrogen of one amino acid to the carbon of the carboxyl group of another amino acid; covalent bond |
| What type of link/bond connects proteins? | peptide bonds (covalent) |
| Primary structure | covalently bonded (peptide bonds) backbone chain of a protein; commonly linear |
| Native protein | protein molecule as it occurs naturally without external influences such as heat or pH changes; commonly coiled |
| Alpha helix & pros? | coiled arrangement of proteins; held together by hydrogen bonds; decreases the stress of only a linear structure |
| Hydrogen bond | formed between a hydrogen atom and an electronegative atom (e.g. oxygen of a carboxyl group); seen in secondary structures |
| Secondary structure | usually the alpha helix of the backbone chain of many proteins; held by hydrogen bonds; may also be a beta pleated sheet |
| Types of bonds that may be associated with tertiary structures | hydrogen bonds, salt bridges, disulfide linkages, and hydrophobic interactions |
| Tertiary structure | distorted convolutions of the helical configuration of a protein; the form in which many proteins occur in nature; 3D shape |
| Why is the hydrophobicity of some proteins important? | R groups are hydrophobic and cause the protein to be drawn together somewhat in tight places to facilitate the formation of hydrogen bonds |
| Quaternary structure | a close aggregation of protein segments; multiple tertiary structures |
| Beta pleated sheet | secondary structure resulting typically when theres a high hydrophobic nature occurring |
| Amphoteric | proteins can be this; function as either an acid OR a base |
| What are the three general types of proteins found in foods? | globular, fibrous, & conjugated |
| Globular proteins | proteins with a tertiary structure that is rather spherical |
| Fibrous proteins | insoluble, elongated protein molecules |
| Conjugated proteins | proteins joined with another substance |
| Examples of globular proteins in foods? | albumins, globulins |
| Albumins | globular; found in eggs |
| Globulins | globular; found in meats/legumes |
| Examples of fibrous proteins in foods? | collagen and elastin |
| Examples of foods for collagen and elastin? | meats and poultry |
| Examples of conjugated proteins? | glycoproteins, lipoproteins, metallopreotein, nucleoproteins, & phosphoproteins |
| Foods of glycoproteins? | various sugars, egg white, soybeans |
| Foods of lipoproteins? | water insoluble compounds such as cholesterol, triglycerides, and phospholipids |
| Foods of metalloproteins? | meats, some contain iron |
| Foods of phosphoproteins? | casein in milk |
| Hydrolysis | splits proteins in primary structure at the peptide linkages |
| isoelectric point | the pH at which a protein molecule is electrically neutral; this specific pH differs for various proteins |
| Why is the isoelectric point importation in food prep? | a protein's minimum solubility occurs at its isoelectric point; when a fluid containing protein (milk) is brought to its IEP,curdling may occur which is irreversible, but can be useful for cheese making |
| How does hydrolysis happen? | usually the result of enzymatic action by peptidases but sometimes collagen is cleaved by acid hydrolysis |
| How does hydrolysis affect solubility? | shorter chains from hydrolysis increase solubility |
| How does hydrolysis affect thickening foods? | shorter chains from hydrolysis decrease the ability to thicken food products |
| Denaturation | relaxation of the tertiary to the secondary structure of a protein accompanied by decreasing solubility of a protein |
| Coagulation | clumping together of denatured proteins |
| Chemical protein changes | hydrolysis |
| Physical protein changes | denaturation and coagulation |
| How can a food be denatured? Coagulated? | denatured: heat, agitation, and UV light coagulated: heating, beating |
| What are the three functional roles of protein in food preparation? | foam formation, thickening agent, and structural component |
| Foam formation of proteins | whipping denatures some proteins; good for angel food cakes, whipped desserts, marshmallows, chiffon pie fillings, meringues, etc. |
| Thickening agent of proteins | egg proteins work when denatured and coagulated by heat; e.g. custards baked, hollandaise, etc.; soybean proteins work to become tofu |
| Structural component of proteins | gluten in wheat flour to make breads, etc.; edible films such as in milk, wheat, and corn proteins form coatings for nuts, dried fruits, and jelly beans |
| How are flesh foods categorized? | meat, poultry, & fish |
| What are examples of meat? | beef, veal, pork, & lamb (red meats from animal sources) |
| What are examples of poultry? | turkey, chicken, & duck |
| What are examples of fish? | fish with fins, gills, a backbone, & a skull AND shellfish |
| What are two types of shellfish? | mollusks & crustaceans |
| Mollusks | have a shell (e.g. snail, clams) |
| Crustaceans | have a hard exoskeleton (e.g. shrimp, crab, & lobster) |
| What is muscle primarily made of? | mostly water then some protein (75:25% plus some other things) |
| Myosin | long & thin protein molecule |
| Actin + Myosin = | actomyosin |
| Tropomyosin | influences the formation/degradation of actomyosin (actin + myosin) |
| ATP in muscles tissue leads to... | lactic acid formation & a drop in pH |
| Neutral phosphatases | influences the water holding capacity of meat and therefore affects juiciness |
| Myofilament | made of actin (thin) & myosin (thick) |
| Sarcomeres | clustered units of myofilaments |
| Myofibrils | organized linearly by the sarcomeres |
| Sarcolemma | holds everything of a muscle tissue together |
| Sarcoplasm | protein surrounding the myofibrils |
| Collagen | fibrous protein found within/between different muslces |
| Tropocollagen | causes a tougher meat due to more covalent bonds forming over time; is a type of collagen |
| Elastin | collagen that is resistant to chemical changes; causes a rubbery texture in meats |
| What are the three layers of connective tissues in meats? | endomysium, perimysium, & epimysium |
| What is the connective tissue in fish called? | mycomatta |
| What is different about fish actomyosin & collagen levels compared to meats? | they are more sensitive to heat |
| What is fat's role in meat? | contributes flavor and juiciness |
| What are some types of meat pigments? | myoglobin (includes oxymyoglobin & metmyoglobin), hemoglobin |
| Myoglobin | purplish, red pigment; predominant pigment in meat |
| Hemoglobin | the largest pigment in meat, but not as abundant as myoglobin |
| When meat is cooked, what pigment change occurs? | oxymyoglobin changes to a grey-brown (e.g. well-done meats) |
| What color can poultry turn at high heats? | pinkish |
| Curing | treatment with nitrates or preserving meat for long-term storage |
| Nitrous oxide myochrome | causes stability of pinkish red tint in cured meats |
| What happens when cured meats are exposed to light and oxygen? | can lead to the fading of pigments and sometimes a fluorescent green/yellow pigment |
| What things can affect the quality of meat? | maturity, postmortem changes (rigor mortis) |
| How does maturity affect meat quality? | Young: more connective tissue w/ little fat Mature: more tender with higher fat & lower connective tissue |
| Postmortem changes in meat | rigor mortis; pH drops & water is pushed out causing rigidity of muscle |
| What is the purpose of aging meat? | to wait until rigor mortis is done |
| What changes happen to meat upon heating? | fat melts, proteins denatured, fibers shrink, water-binding capacity is reduced, & I-bands crack |
| What happens to meat's tenderness when heated? | becomes less tender; elastin does not change, but collagen softens |
| What happens to water when meats are heated? | water is lost because bound water converts to free water (free water offsets water loss in the beginning of cooking) |
| Water-binding capacity | amount of water held by muscle protein as bound water |
| If water-loss exceeds the water available, what happens to the meat quality? | reduced juiciness |
| What are some examples of dry heat cooking methods? | roasting, broiling, pan broiling, pan frying, deep fat-frying, etc. |
| What type of meat should be used for dry heat? | tender cuts |
| What heating method produces the greatest cooking loss? | dry heat: roasting or broiling |
| Cons to microwave cooking of meats? | greater cooking loss, decreased juiciness, negative tenderness, and unappealing grey texture |
| What are some examples of moist heat cooking methods? | braising or stewing |
| What type of cuts are best for moist heat cooking methods? | NOT tender cuts; choose ones with high connective tissue (e.g. crock pot) |
| What happens with the extended cooking time of meats in moist heat methods? | collagen is converted to gelatin without the toughening of muscle proteins |
| Drip losses | juices and fat that drip from meat during cooking |
| Evaporative losses | difference between weight of uncooked meat and weight of uncooked meat plus drippings |
| Cooking losses | total losses from meat by evaporation and dripping during cooking |
| What can cause higher cooking losses? | foil, slow cooking methods, & higher temperatures |
| What effect occur in meat when their pH is alkaline? Acidic? | Alkaline: darkens color & no increased tenderness Acidic: increased tenderness & juiciness; negative aroma/flavor possible |
| What effect does salt have on meats? | enhanced water retention (improves juiciness) plus some tenderness promotion and definitely enhances the flavor! |
| What are three mechanical tenderization methods for meats? | pounding, cubing, & mechanical (e.g. extrusion) |
| Restructure meats | meats made from creating small particles, adding fat/other ingredients and shaping into uniform portions (e.g. McRib) |
| Comminuted meats | made by pulverizing meats & adding fat/salts (e.g. hot dogs) |
| Surimi | purified & frozen minced fish containing a preservative (e.g. pollock in fish sticks OR commonly used for imitation crab) |
| Soy protein concentrate vs. isolate? | Concentrate: defatted soy protein Isolate: defatted & highly concentrated soy protein |
| Textured soy protein (TSP) | end product of a series of tests producing fibers from soybeans |
| Soy grits | coarsely ground soy flakes; used commercially to alter texture of ground meats |
| Soy flour | finely ground soy flakes; lack of gluten causes limitations; best used with wheat flour |
| 3 different forms of tofu? | firm, soft, & silken |
| What are some fermented soy products? | temphe, natto, & miso |
| Mycoprotein | protein produced by a fungus; suitable for making meat analogs |
| Gelatin | protein derived from collagen when heated for an extended period of time; used for gel formation |
| Sol | solid dispersed in a liquid |
| Enzymatic hydrolysis | proteolytic enzymes able to cleave long gelatin molecules; eliminates the ability to form gel; careful when adding fruits (e.g. pineapple, papaya, etc.) to sols/gels |
| Gelatin sol | gel forms as a sol is cooled |
| Which produces a strong gel: milk or water? | milk |
| What affects the stability of gels? | Rate of cooling, pH (best between 3-3.5), and added sugar (sets more quickly with increased tenderness) |
| Thixotropic | can revert back to a sol when agitated; e.g. gelatin gels (occurs with great rise in temperature) |
| What is the general chemical structure of simple fats? | fatty acid + glycerol=ester (via esterification); made of Carbon, hydrogen, & oxygen |
| Saturated fatty acid | no double bonds; all carbons are saturated with hydrogens |
| Unsaturated fatty acid | at least one double bond |
| Monounsaturated fatty acid | one double bond |
| Polyunsaturated fatty acid | more than one double bond |
| What determines the physical characteristics of a fatty acid? | its structure |
| What structural components affect fatty acid physical characteristics? | amount of saturation, chain length, & cis/trans formation |
| Monoglyceride | 1 glycerol + 1 FA |
| Diglyceride | 1 glycerol + 2 FA |
| Triglyceride | 1 glycerol + 3 FA |
| What happens when fats cool to a solid? | the molecules form crystalline matrix |
| What are the 4 forms of crystals of solid fats? | alpha, beta prime, intermediate, & beta |
| Alpha form of solid fats | fine, unstable |
| Beta prime form of solid fats | next step larger than alpha; smooth, stable; desirable form for baking |
| Intermediate form of solid fats | grainy fat (occurs when beta prime melts and reforms in this larger form) |
| Beta form of solid fats | very stable; largest form |
| What happens to fat in foods when they are stored improperly? | the beta prime crystals may melt with higher temps and the fat recrystallizes in the larger forms of intermediate or beta crystals--leads to coarse texture --also rancidity may occur |
| Where does oxidative rancidity take place on a fatty acid? | on the double bond in an unsaturated fatty acid of a fat (oxygen is added there) |
| What forms from oxidative rancidity? | a free radical that then combines with oxygen atoms to form a peroxide, then one hydrogen is added to make a hydroperoxide |
| Oxidative rancidity | development of off flavors/odors in fats as a result of the uptake of oxygen and the formation of peroxides, hydroperoxides, and other compounds |
| Why is oxidative rancidity autocatalytic? | it is self-perpetuating because new free radicals are formed when a hydrogen atom is removed from the second fatty acid to add to another, thus allowing two oxygens to be added to the second free radical and begin the process over again |
| What can delay oxidative rancidity? | antioxidants, storage in tightly closed containers in a cool, dark place |
| What are examples of synthetic antioxidants? | TBHQ (vegetable oils) |
| What are examples of natural antioxidants? | BHA, BHT, & PG |
| Hydrolytic rancidity | free fatty acids split off of a glycerol molecule due to lipase or heat |
| Reversion | development of an off flavor (beany/fishy) in soybean, rapeseed, or fish oils as a result of a reaction involving only very minor amounts of oxygen |
| What fatty acids does reversion occur in? | some of the linoleic and linolenic acids |
| Smoke point | occurs as degradation begins; temperature at which a fat or oil begins to emit some traces of smoke |
| How does acrolein form? | its a highly irritating and volatile aldehyde formed when glycerol is heated to the point oat which two molecules of water split from it |
| Does acrolein form at a specific temperature? | near the smoke point; commonly occurs in frying when the fats have high glycerol content after lipolysis; the drop in smoke point is at about 190C |
| Polymerization | formation of a variety of polymers, including simple dimers & trimers, when free fatty acids are subjected to intense heat for a long period during frying |
| Acrylamide | carcinogen formed from natural sugars and asparagines in starchy fried foods and also in baked products |
| How does polymerization occur & what happens to the quality of the fat? | Occurs when new carbon-carbon bonds are formed & dimers/trimers of a cyclic nature evolve from the free fatty acids; quality decreases due to increase of viscosity and darkening of color |
| Acrylamide is found in what conditions? | can form at high temperatures in foods containing the essential components (not found naturally in foods) |
| What foods are susceptible for forming acrylamide? | potatoes and baked products containing starch, natural sugars, & some proteins are often heated at high temps are susceptible; potato chips, french fries, roasted coffee beans, etc. |
| What are the steps in manufacturing food fats (4)? | extraction, refining, fractionation, & crystallization of fats |
| Extraction of fats | removal of lipids from their natural food sources |
| Rendering | removing fat form animal tissue (can be wet or dry rendering) |
| Cold pressing | mechanical pressing to express heat which results in an oil (higher quality) |
| Hot pressing | using steam to heat plant seeds to about 70C and then pressing to remove oil (lower quality) |
| What are some examples of refining processes? | degumming, neutralizing, bleaching, deodorizing, winterizing |
| Degumming | refining; separating natural gums from extracted fats |
| Neutralizing | refining; removing free fatty acids from fats and oils |
| Bleaching | refining; coloring and flavoring contaminants are removed from fats and oils |
| Deodorizing | refining; steam distillation |
| Winterizing | refining; remove lipid fractions with high melting points |
| Fractionation | separating oils into fractions using controlled temperature to crystallize fatty acids with high melting points from oils with low melting point; helps lower trans fat |
| Tempering | removing heat to control temperature in order to promote the formation of desirable crystals |
| Bloom | discolored and granular areas as a result of melting less stable crystals and recrystallization as beta crystals on the surface |
| Methods of quality determination for fats? | chromatographic analyses, iodine number, peroxide value, free fatty acid content, & standardized testing |
| Hydrogenation | addition of hydrogen to an unsaturated fatty acid in the presence of a catalyst to reduce the unsaturation of the molecule and raise the melting point |
| Isomerization | results in formation of trans fat |
| Elaidic acid vs. vaccenic acid in fats | elaidic acid: elevates LDL levels vaccenic acid: does not raise LDL levels |
| Interesterification | uses melted fat; sometimes its kept below its melting temperature |
| Intraesterification | fatty acids split from glycerol and rejoin in a different configuration, but with the same fatty acids being retained |
| What are some efforts to reduce trans fats in foods? | changing the oil being used, extent of hydrogenation, changing fatty acids through selective breeding & genetic alterations |
| Sources of lipids in foods? | animal fats, plant lipids, & fish oils |
| Examples of animal fats? | butters & lard (generally higher in saturated fatty acids) |
| Where does cholesterol occur in fats? | only in animal fats |
| Plant lipids | range from fluid oils to solid fats; usually higher in polyunsaturated fatty acids |
| Ways to modify plant lipids? | selective plant breeding, genetic engineering, etc. |
| What is margarine made from? | hydrogenated plant oils |
| Plasticity | able to be spread/creamed |
| Lard | a fat product rendered from pigs |
| Shortening | main part of manufacturing is in the hydrogenation of vegetable oils |
| Shortenings & lard are essentially all.. | fat |
| Is butter all fat? | nope! fat + water |
| Beef tallow | fat rendered from cattle; generally isn't used as a single source in the marketplace |
| What are the 4 functional roles of fats? | flavor, color, tenderness, & texture |
| Use of color in fats? | margarine is colored to look like butter, vegetable shortenings have beta-carotene |
| Flavor of fats | adds richness--people prefer butter flavor so margarines have added butter flavoring |
| Texture of fats | pastry, shortened cakes, bread dough, fried foods |
| Best results for frying foods? | high temperatures without crowding |
| Tenderness of fats | important in baked products; fats prevent contact between water & flour proteins |
| Shortening power | the ability of fats to prevent contact between water and flour proteins (Fat coats the surface of gluten and causes the water to not completely moisture the gluten which can increase tenderness) |
| Plastic fats shortening ability? | they have more shortening power |
| Emulsification? | hydroxyl groups in shortening helps it be an emulsifier; lecithin in egg yolks is too |
| Fats as a cooking medium? | good because they can be heated to high temperatures |
| Dehydrating process of fats | loss of water from the food into the oil |
| Fat replacers | can be protein, fat, or carb based |
| Olestra | fat replacer that is a hybrid between carbohydrate and fat |
Created by:
amay322