Chapter 10: Milk

flavored fluid milk

because milk contains 88% water, most flavorings agents are water-based so they will dissolve and stay in solution within milk

Milk solids-not-fat (MSNF)

federal standard identifying the total solids, primarily proteins and lactose, found in milk, minus the fat

milks from other animals

goat (2nd most after cows), sheep, camel, reindeer, water buffalo *if animal has a mammary gland, it can produce milk*

prebiotic

non-digestible food ingredients (generally fibers such as fructooliugosaccharides and insulin) that support the growth of probiotics

raw milk

not pasteurized and not homogenized

Ultrahigh-temperature pasteurization

milk that has been pasteurized using very high temperatures (280°F-302°F), is aseptically sealed (sterile), and is capable of being stored unrefrigerated for up to 3 months -after aspetic seal is broken, must be refrigerated

eggnog

-eggs, cream or milk, nutmeg, spirits -pasteurized and homogenized mixture of milk, cream, milk solids, eggs, stabilizers, and spice -6-8% milk fat (double of whole milk) -9% MSNF -1% egg yolk solids

instant milk

-exposing NFDM to steam, then re-dried -makes it agglomerate and dissolve instantly in water agglomerate = to gather into a mass or ball, in case of milk, smaller protein particles regroup into larger, more porous particles

color compounds

-factors that contribute: fat, colloidally dispersed casein and calcium complexes, water-soluble riboflavin -compounds interfere with light transmission: makes so light cannot pass through causing white, opaque, ivory color -amount of carotene in feed influences color (more yellow) -riboflavin and carotenoid pigments dissolved in milk fat give yellowish tinge to butter and cream

kefir

-fermented milk drink and probiotic; bubbly, fizzy, thick -made by adding bacteria from kefir grains to milk -contains 1% alcohol and a little carbon dioxide -initially heated to 185 F then cooled to ferment to soft, foamy curd

Food Additives

-food additives are vitamin A and D -recombinant bovine growth hormone (rBGH) is given to cattle to make them produce more milk -steroid hormone use is not permitted in dairy cattle (not like cattle raised for meat)

Grades of Milk

-graded according to bacterial count that survived (pathogenic bacteria are killed) -1-5% of non pathogenic bacteria still remain in milk, convert lactose to lactic acid (what makes milk go sour) -Grade A: lowest bacteria count, MUST be pasteurized -Grade B: not as common -grades of nonfat dry milk: US extra and US Standard -volunatry and paid for by the processor -Done by the USDA

pasteurization temps

145 (for 30 mins) and 161 are most common temperatures -161 is HTST - high temp short time -145 is LTLT - low temperature longer time -UP = 280

reduced fat and low fat milk

-2% and 1% respectively -min of 8.25% MSNF necessary (if past 10% must be labeled "protein-fortified") -vitamin A fortification is required, vitamin D is optional -104 mg sodium in low fat reduced: 121 kcal/cup, 5g fat low fat: 102 kcal/cup, 3g fat

whole milk

-3.25% milk fat and 8.25% Milk-solids nonfat (MSNF) -120 mg sodium -usually fortified with vitamin A and D, but optional -150 kcal/cup, 8g fat

cholesterol

-33 mg in a cup of whole milk -18 g in reduced fat (2%) -4 mg in fat-free

fat and kcal content

-8 oz cup provides 86-150 kcals -buttermilk only has 2 g fat per cup and fewer than 1/2 the calories of whole milk

reduced lactose milk

-Pasteurized milk treated with the enzyme lactase, converting lactose to glucose and galactose. -Results in a slightly sweeter flavor -More easily digested by most people who have some degree of lactase deficiency

lactose

-a disaccharide (glucose+galactose) extracted from the whey found in milk -2-8% milk by weight -improves water holding capacity of processed meats (ham) -color of baked goods (browning ability) -also texture of frozen desserts

Pasteurization

-a food preservation process in which liquids are heated to a specified temperature for a specific period of time to destroy most microorganisms that could cause disease, spoilage, or undesired fermentation -destroys almost 100% of pathogenic bacteria, yeasts, molds and 95-99% of other non-pathogenic bacteria -inactivates enzymes that cause off flavors of rancidity -required -measure activity of certain enzyme (alkaline phosphatase), if no longer active, then milk is safe for consumption -145°F (for 30 mins) or 161°F are most common

Homoginization

-a mechanical process that breaks up the fat globules in milk into much smaller globules that do not clump together and are permanently dispersed in a very fine emulsion; no affect on nutrient content -prevents separation of the fat and the water (prevents creaming: keeps fat suspended in water, creaming is when it separates and fat comes to the top and can be scooped off ) -milk becomes creamier texture, whiter color, blander flavor -increased surface tension/area gives better foaming-capacity -more prone to rancidity -pasteurizing before homogenization inhibits rancidity

Ultrapasteurization (UP)

-a process in which a milk product is heated above 145°F but below 280°F for .01 to 15 seconds (higher temp, shorter time) refrigeration still required

imitation milk

-a product defined by the FDS as having the appearance, taste, and function of milk, but as being nutritionally inferior -little or no dairy content -water, corn syrup solids or sugar to replace the lactose, vegetable oils to replace the milk fat, protein from the sodium caseinate in soybeans, whey or MSNF to sub for the protein, and some stabilizers, emulsifiers, and flavoring agents

sweetened condensed milk

-added sugar (also contributes to the maillard reaction) -evaporate the water by 50% weight then add 15% sugar -28% total milk solids and 8% milk fat -does not have to be sterilized because high sugar content prevents microbial spoilage(40-45% by weight sugar concentration)

acid coagulation

-adding acid to milk causes casein (but not whey proteins) to coagulate (film at the top_ -casein precipitates when normal pH of 6.6 drops below 4.6 (4.6 is caseins isoelectric point: no charge) -sources: lemon and lime juice, tomato products, fruits, acid producing bacteria in cultured milk products -add acid to milk base to prevent milk from coagulating (curdling) and avoid high temps after acid has been added -not as much calcium in acid-coagulated milk as enzyme-coagulated milk because it is released from the casein molecule and gets lost in the whey FORMULA: calcium phosphocaseinate -->(with acid) neutral casein (gel) + Ca2+ (lost in whey)

other ingredients added to yogurt

-after fermentation, gelatin and NFDM are added to make firmer texture, reduce precipitation of acidity, add color

storage of milk: refrigerated

-all fluid milk (except unopened aseptic packages of UHT pasteurized milk and certain canned milk products) should be stored in the fridge -containers should be closed or covered to avoid rancidity, microbial contamination, and absorption of odors from other foods -oxidative rancidity (bc of exposure to oxygen) or hydrolytic rancidity (exposure to water) are problems bc of large amounts of short-chain fatty acids in milk -store in proper opaque containers to reduce exposure to light, which triggers oxidation, resulting in off-flavors and loss of riboflavin -shelf life can be extended by addition of carbon dioxide, disrupts microbial functions (often with cottage cheese)

lactic acid bacteria

-bacteria used to ferment dairy products in the US are often "lactic-acid producing bacterial cultures" or "propionic acid-producing bacteria" -only yogurt is mandated to be made with specific bacterial strains (lactobacillus bulgaricus and streptococcus thermophilus)

minerals

-calcium (300 mg in 1 C) 80% of calcium ingested by Americans comes from dairy products -phosphorus, potassium, magnesium, sodium (104 mg, 120 mg, in whole), chloride, and sulfur -low in iron

fat in milk

-called "milk fat" or "butterfat" -plays role in flavor, mouthfeel, stability of milk products -consists of triglycerides (glycerol backbone with 3 fatty acids) surrounded phospholipid-protein membranes, allow them to be dispersed in fluid portion of milk -most are short-chain fatty acids -mainly saturated fat

Milk protein concentrates (MPC) & Milk protein isolates (MPI)

-casein and whey proteins isolated from fresh nonfat milk (42-85% protein) that are high in bound calcium -natural milk flavor ideal for baby formula, sports nutrition items, cheese products

chocolate milk

-chocolate flavoring comes from cocoa, natural or Dutch chocolate, chocolate liquor, or chocolate syrup -requires a stabilizer to prevent cocoa from settling out of milk: kappa II carrageenan, cellulose, guar gum, xanthan gum, locust gum (also add foaming characteristics -1.5% liquid chocolate or 1% cocoa and 5% sugar

cream

-collection of fat globules that come to the top of non-homegenized whole milk -heavier and thicker the cream is, the higher the fat content -cooling the cream firms its fat globules making it even thicker -combining cream with pasteurized or un-pasteurized milk makes half-and-half

Whey protein concentrate (WPC) or Whey protein isolates (WPI)

-concentrated whey higher in protein (35%, 50-80%, 80+% protein), low in lactose and minerals -dry beverage mixes, nutrition bars, protein-fortified food, sports nutrition products

fat-free or nonfat milk (skim)

-contain mo more than 0.5% fat -min of 8.25% MSNF -vitamin A fortification required, D is optional -86 kcal/cup, 0 g fat

buttermilk

-contains little or no butter fat (100 calories/cup, 2.2 g fat) -made from non-fat, reduced fat, or low fat milk -1.3 g saturated fat -traditionally: natural butter milk was liquid leftover after fresh cream had been chilled and churned to produce butter -streptococcus lactic is used, convert sugar (lactose) into lactic acid, gives buttermilk more sour flavor -as milk becomes more acidic, pH falls, proteins precipitate out--> becomes more sour, more bubbly, and thicker -longer shelf life because of the acid and lower fat content -<0.5% milk fat, at least 8.25% MSNF -acidic pH of 4.6

vitamins in milk

-contains vitamin A and D, riboflavin (b2), and tryptophan -low in vitamin C and E -milk exposed to ultraviolet light looses riboflavin: why its packaged in cardboard or opaque containers

temperature

-cooling cream increases its viscosity or firmness and its tendency to clump -refrigerate cream, bowl, and beaters at 45 F for at least 2 hours -room temp: fat globs spread out and do not capture the air bubbles as well, not as much firmness, softer texture -heating process of pasteurization kills an enzyme that helps fat globules cluster, so non-pasteurized creams whip more readily and have smoother texture

sour cream

-cream can be soured by adding Streptococcus lactis bacteria -fermented until acidity reaches 0.5% -produced if MSNF, vegetable gums, or certain enzymes are added -min of 18% milk fat is required

whipped cream (factors of stability)

-cream expands to 2 to 3 times in volume when whipped -stability of milk foam is dependent on fat content, temperature of cream, age of cream, sugar content, and length of whipping time

yogurt

-created when bacteria are added to milk to ferment the milk's lactose to lactic acid, increasing acidity -made by adding lactobacillus bulgaricus and streptococcus thermophilus to pasteurized, homogenized milk and some MSNF are also added -held at warm temperature to encourage fermentation -fermentation decreases the amount of lactose to 4% -at least 8.25% MSNF and 0.5% acid

whey powder

-crystalizing whey creates a sweet or acidic powder high in lactose and minerals. demineralized and delactosed whey powders are also available -infant formulas, dry mixes, confectionaries, processed cheese, weight-loss products

curd formation

-curd: the coagulated or thickened part of milk -increased acid concentration causes the casein to precipitate out, gives milk a more curd-like consistency -bacteria influence the quality of fermented dairy products through the amount and type of acids they produce -some protein is also broken down to provide nitrogen for bacterial growth, this makes the curd softer and more digestible

fat content

-higher the fat content of the cream, the more stable the whipped cream (fat globules help suspend air pockets) -less fat: softer, less stable foam -solid fat particles create more rigid foam -heavy-whipping cream is better than lower-fat but becomes lumpy and buttery when over-beaten -heavy-whipping cream has lower moisture content, prevents crusts from becoming soggy -most whipping creams are sold non-homogenzied to allow for easier aggregation of fat globules -when cream is homogenized, proteins surround the smaller more numerous fat globules instead of being available to envelop the air bubbles -vegetable gums and gelatin are sometimes added

Active Cultures in yogurt

-if fermented then chilled, cultures remain alive -if heated, the cultures are destroyed -if have live bacteria are labeled "with active yogurt cultures" -does not necessarily mean they are alive

UHT Milk

-in laminated aseptic cartons, when unopened can be stored on shelves for up tp 3 months -refrigerated once opened -"cooked" flavor at first, disappears with storage time -off-flavors like sweet, flat, musty, rancid, chalky -ideal for boating, camping, hiking, where refrigeration is not available

carbohydrates in milk

-lactose (milk sugar) is the main carb -12g per 8oz glass -when bacteria metabolize lactose, lactic acid is produced -flavor of cheeses and fermented milk products (yogurt and sour cream) is derived from lactic acid -lactose less soluble then sucrose: causes it to crystalize into lumps in nonfat dry milk and sandy texture in ice cream

enzymes in milk

-lipases, proteases, alkaline phosphatase (tests for pasteurization) -if alkaline phosphatase levels are too high, milk has not been pasteurized correctly

whipped milk products

-liquid milk such as cream, evaporated milk, and reconstituted NFDM can be made into foam by whipping air into the liquid -the protein in these milk products is mechanically stretched into thin layers that trap air bubbles, fat particles, and liquid

probiotics

-live microbial food ingredients (bacteria) that have a beneficial effect on human health -beneficial affects on gut health -improves intestines microbial balance, aid in digestion, produce helpful enzymes -HCL kills bacteria inside you so not all probiotics survive -any fermented dairy product are most common type of probiotic food

filled milk

-made by replacing all or part of the milk fat with a vegetable fat -no cholesterol -higher in saturated fat from coconut or palm oils -regulated at state level

rice milk

-made from brown rice, filtered water, and small mount of brown rice sweetener -some are made with barely enzymes to converts carbs in brown rice to naturally occurring sugars

caseinates

-made from caesin by adding sodium, calcium, potassium, or combinations of these salts (to make it water soluble) -primarily medical foods, nutrition bars

almond milk

-made from ground almonds -longer shelf life

soy milk

-made from soybeans that have been soaked, ground, and strained

Hydrolysates

-manufactured by the enzymatic hydrolysis of milk proteins -improves stability, solubility, viscosity, emulsification, and whipping ability high viscosity = high resistance emulsification = making 2 immiscible substances mix together

Enzyme coagulation

-milk coagulates when combined with certain enzymes originating from animal, plant, microbial, or genetically modified microbial sources -most common: chymosin (or renin), used in production of ice cream and cheese -enzyme coagulated clots are rich in calcium and have tough, rubbery texture, unlike those created by acid (which are less elastic and more fragile) -cheddar cheese (enzyme coagulated) is higher in calcium than cottage cheese (acid coagulated)

Function of Milk in Foods

-milk proteins are added to many foods for taste and to boost nutritional value -emulsification and stabilizing (keeping other compopnents dispersed evenly, surround other food components and keep in suspension)-moisture, mixing ability, flavor

acidophilus milk

-milk that is cultured with Lactobacillus acidophilus, letting it incubate at 99 F -breaks down lactose into glucose and galactose -twice as many sugar molecules --> makes it sweeter

separation of whey proteins

-much smaller, compact, globular helical proteins -easily separated from larger casein proteins by addition of acid, which percipitates the casein but leaves the whey proteins in solution -decreasing pH from 6.6 to 4.6 or lower releases calcium phosphate, magnesium, and citrate ions from interior of micelles

cream substitutes

-non-dairy ingredients (coconut milk or oil, vegetable milk) water, vegetable oil, corn syrup solids, sodium caseinate, soy protein, emulsifiers, vegetable gums, coffee whiteners, artificial flavors and colors -whipped toppings, coffee creamers, dry mixes, imitation sour cream, snack dips

Dry storage

-nonfat dry milk, ultrapasteurized milk, evaporated milk, and sweetened condensed milk are stored at or slightly below room temp (72 F) -NFDM should not be exposed to moisture: humidity will make it lumpy and stale -containers tightly closed to avoid exposure to oxygen -NFDM - 1 year, doubled in refrigerated -ultrapasteurized: unopened at rom temp for up to 3 months -once opened, all these milks should be treated like fresh milk: refrigerated

grain milk

-oats, barley, wheat, rye, flour mixed with water -lower protein content and higher carb content than dairy milk

flavor changes

-percentage of fat determines mouthfeel and body of a particular milk -bland, slightly sweet flavor of milk comes from its lactose, salts, sulfur compounds, and short-chain fatty acids -exposure to heat or sunlight, use of copper equipment, feed ingested by source animal, oxidation of fatty acids, looses its vitamins -"cooked" flavor of heated milk has different flavor: whey proteins are denatured and gives distinct flavor, releases volatile sulfur compounds that give different flavor -heat too high -> off flavors -rag week, wild onions, turnips, beets, potatoes, cabbage can be tasted in milk

whipping time

-physical agitation is necessary bc it disrupts the phospholipid membranes surrounding the fat globules, preventing them from aggregating -necessary to stretch the proteins to denature them to stretch around the air pocket -overbeating is a mistake: turns whipped cream into butter and whey -beat on medium high then slowly lower speed to check: lift beaters to see if the cream is falling into glossy, large globs with soft peaks -stiff yet moist peaks

whipped reconstituted nonfat dry milk

-prepared NFDM powder can be whipped into a foam but it is very unstable -less expensive and lower in cals and fat

evaporated milk

-produced by evaporating at least 60% of water found in whole milk -7.5% milk fat 25.5% MSNF -stabilizers are added to prevent separation of fat during storage, get solids dispersed -high temps of canning and metal of the can may impart cooked and off-flavors -first expose milk to high temp (203) for 10-20 mins to stabilize casein so that it will not coagulate during sterilization -heat milk to 121 to 131 F at reduced atmospheric temp to get it to boil -homogenized, canned, sterilized -to reconstitute, combine with equal volumed canned milk and water -fat free evaporated milk must contain <5% fat, at least 20% total solids, vitamin A and D

protein

-protein in milk is a complete protein -1 cup milk = 8g protein -adding milk protein to other foods improves texture, mouthfeel, moisture retention, and flavor -whey proteins often added to grains low in lysine

nonfat dry milk (NFDM)

-removing all of the moisture from milk -as they go through the process, loose 20% of vitamins -no fat is left: longer shelf life, 1 year) -thickening agent, baby formula, elderly

salts

-salts in cured ham, some canned veggies, and some seasonings can cause milk to curdle -to prevent: salts should be added to the milk base -avoid high temps after these salts have been added

polyphenolic compounds

-some fruits, vegetables, teas, and coffee contains slightly acidic polyphenolic compounds and when combined with milk, result in precipitation of proteins -also contribute to the curdling of cream or milk that occurs during prep of scalloped potatoes or tomato or asparagus soup

coagulation and precipitation

-some milk proteins coagulate or precipitate to form a solid clot, or curd, under certain conditions -makes it possible to produce yogurt and cheese -heat, addition of acid, enzymes, polyphenolic compounds, and salts

sugar content

-sugar increases the stability of whipped cream -needs to be added gradually and towards the end of the whipping time -if added earlier, it will increase whipping time and reduce overall volume and rigidity by delaying the clumping of fat (competes with other solutes) -sugar lessens likelihood of overbeating the cream -powdered better then granulated: dissolves more readily -cornstarch in the powder acts as a stabilizer

whipped evaporated milk

-the high concentration of milk solids in evaporated milk makes it possible to whip it to 3 times its volume -flavor, texture, stability is less acceptable bc of its lower fat content and lower viscosity -add lemon juice, sugar, or chill it to increase stability -flavor of evaporated milk overpowers other flavors

caesin

-the major protein found in milk. -can be percipitated (solidified out of solution) with acid or certain enzymes -improves nutritional value of bakery items, medical foods; binder in processed meats, boosts protein content in imitation cheese

age

-the older the cream, the greater its viscosity and ability to foam will be -whipping cream must be at least 1 day old (1-2 days)

Vitamin A an D Fortification

-vitamins A and D are fat soluble and are found in milk fat -whole milk is not required to be fortified with either vitamin -98% of milks are fortified or enriched

heat coagulation

-when milk is heated, the whey proteins (lactalbumin and lactoglobulin) become insoluble, mesh with the milk's calcium phosphate, and precipitate, forming a film at the bottom and sides of the pan (calcium goes to the top) -avoid scorching and precipitating of whey proteins by constant stirring -casein will not coagulate with heat -canned evaporated milk with higher concentrations of casein may coagulate during high heats of sterilization, warm milk prior to avoid

% Milk Fat

3.7%

low sodium milk

6 mg of sodium (compared to 120 in cup of regular milk)

% Milk Solids-non-fat (MSNF)

8.9%

ensures the sanitation of dairy farms and processing plants

US Public Health Service

4 main proteins in milk

Casein: alpha-casein beta-casein Whey: beta-lactoglobulin alpha-laclalbumin

chymosin (rennin)

an enzyme sold commercially as rennet that causes milk to clot, forming a curd

casein micelles

casein proteins are not very soluble in water (both alphas and beta casein is hydrophobic and k-casein is hydrophillic) so they form casein micelles in water medium of milk -caseins and calcium phosphate gather in clusters of individual protein molecules

standards of identity

certain parameters of a food must be met to be called that food, manufacturers have to meet these standards

pH of milk concentration of water

high concentration of water (87.4%) gives milk almost neutral pH (6.6)

whey

the watery component of milk removed from the curd in cheese manufacture. consists primarily of water (93%), lactose, and whey proteins: lactalbumin & lactoglobulin isolated by ultrafiltration process, resulting in protein concentrates that are used as emulsifiers, foaming and gelling agents

coagulate

to clot or become semisolid. in milk, denatured proteins often separate from the liquid by coagulation (homogenized milk coagulated more easily)

what influences milk's content

type of feed, breed, stage of lactation, season of the year

"fresh fluid" cow milk

whole reduced fat (2%) low fat (1%) fat free (nonfat)