Milk and Milk products+Meat Fish and Poultry

Question 1

whole milk composition
nutrient content varies

Answer 1

88% water
5% carbohydrate
3.5% protein
3.3% fat
species-to-specices, breed-to-breed, and seasonally
fat content in cows vary considerably
accepted standard is 3.3-3.7%

Question 2

What is notable about milk fat
what types of proteins in milk are used as emulsifiers and why

Answer 2

the array of fatty acids in its triglyceride molecules
Lipoproteins contain hydrophilic and hydrophobic
components—making them effective emulsifiers.
Even with this protection, cream separates from the aqueous
portion of fresh, unprocessed milk.

Question 3

The triglycerides in milk are dispersed as tiny fat globules surrounded by a fat-globule membrane of _____ and _____
A cup of milk contains _______ g of carbohydrate which tends to precipitate easily at cool temperatures.
 Crystals of _____form during processing of dried milk solids

Answer 3

phospholipids and proteins
11-12g
α-lactose

Question 4

The two basic categorizations of milk proteins are ____ and ____
_____is insoluble, and precipitates readily to form a soft curd—leaving
_____, a watery mixture.
The three predominant forms of casein are ______
A fourth form______,is not as abundant
_____ molecules are joined into raspberry-like organized aggregates
called ______

Answer 4

casein and whey
casein, whey
αs -casein, β-casein, and κ-casein;γ-casein
casein, micelles

Question 5

Milk contains enzymes _____,______, ______, and _____. Their resistance to denaturation by heat varies.
Milk is an outstanding source of most nutrients except ____ and ______

Answer 5

alkaline phosphatase,
lipase, protease & xanthine oxidase.

iron and vitamin c

Question 6

Compounds that contribute to the flavor profile of milk include ______ notably ______, _____, and _____.
The compounds actually in a certain sample are determined by the ____ of milk such as ____, ____, and ____

Answer 6

volatile organic compounds.
 Notably aldehydes, ketones, and acids.
previous treatment
heating, fermentation, and storage

Question 7

On standing, fat globules in milk tend to aggregate into clusters and
rise to the top of the milk. This process of separation is called _______
 Homogenization causes milk to lose its ability to cream not only because it yields tiny fat globules.
 Milk is forced through tiny apertures at high pressure.
 The resulting tiny fat globules have a reduced ability to bind together.

Answer 7

creaming.

Question 8

Homogenized milk characteristics

Answer 8

 Has increased viscosity and a whiter appearance.
 Is less stable to heat.
 Has more sensitivity to oxidation caused by light.
 Foams more readily than it did before processing.
 Has a less distinctive flavor

Question 9

How are canned milk produced and how does this change their composition?
What happens to some lactose and milk proteins during the the evaporation process?
How is sweetened condensed milk made and what is this more prone to?

Answer 9

produced by eveaporation under partial vacuum so water can be removed at a lower temperature this helps to minimize flavor and color changes this doubles the concentration of protein and fat
these proteins undergo mallard reaction
large amounts of sugar is added to evaporated milk this is very prone to non enzymatic browning

Question 10

milk powder consists of:
 Lactose in either an _____ or _____ state.
 Fat in _____ or _____.
 Protein in the form of ________
 Precipitated _______, with air interspersed throughout.

Answer 10

amorphous or a crystalline
globules or free
casein micelles.
whey proteins

Question 11

_____ is used to ferment lactose in milk and milk products to produce ______
______ is somewhat thickened as a result of fermentation
Whey can be fermented to produce _________ such as Mysost and Gjetost
Yogurt is ______ to the point a ____ forms this is a result of fermentation and _____

Answer 11

Microorganisms
lactic acid
buttermilk
sweet cheeses

acidified
gel
controlled heat

Question 12

Butter is a water-in-oil emulsion containing about __% waterand at
least __% fat.
 Usually churned from ______

Answer 12

15
80
sweet cream

Question 13

How are creams produced?
They vary in fat content from____-____

How is sour cream made?

Answer 13

centrifugation of milk to separate lighter cream from
the aqueous portion.
They vary in fat content from 10.5% (half-and-half) to 36% (heavy whipping
cream).
holding period of t 74–82°C
(165–180°F). that pasteurizes the cream; destabilizes some proteinsLactic acid-forming bacteria & controlled incubation generate the acid needed to form the clot. Gums may be added to contribute some thickening.

Question 14

How are natural cheeses categorized

Answer 14

Natural cheeses are categorized according to their firmness or
moisture content.
 Some undergo a ripening or aging period.
 Microorganisms are often are added deliberately.
 Which causes many of the chemical degradative
reactions in the fats—as in various blue cheeses.
 The appearance of some cheeses is unique because of the changes
during ripening.
 Holes in Swiss cheese are caused by formation CO 2.

Question 15

What are the other types of cheeses and moisture levels? how are pasteurized cheeses made?

Answer 15

Pasteurized process cheeses are made heating natural cheeses and adding
an emulsifying agent, moisture level ~41%.
 Process cheese food is similar, with a moisture level ~45%.

 Process cheese spread has a moisture level of ~50%—for easy spreading.
 Coldpack (club) cheeses are also made of natural cheeses with
emulsifiers.
 But are not subjected to heat treatment.

Question 16

Whey uses and where does it come from/

Answer 16

Whey protein concentrate is a by-product of cheese—making,
available in large quantities.
 It is useful in promoting water retention in some meat
products.
 From a tendency to promote gel formation.
Whey protein concentrate can be texturized into powders,
crumbs, ribbons, and chunks.

Question 17

What is ice cream?
what is the federal standard for this food?

Answer 17

Plain ice cream is a frozen mixture of cream, milk solids &
flavorings into which air has been stirred.
 A federal standard of identity for this food is:
 At least 10% milk fat.
 20% total milk solids.
 Optional additives (0.5% stabilizer; 0.2% emulsifier)

Question 18

A frozen ice-cream product
is a ______dispersion
classified as a _______.
The _______form the solid continuous phase.
__________is
the discontinuous or
dispersed phase

Answer 18

colloidal
foam
ice crystals
Air incorporated from
agitation during freezing

Question 19

What is required for the smooth texture in ice cream?
What depresses the freezing temp below the freezing point of water?
How is fast freezing done?

Answer 19

Rapid freezing is required for the formation of fine ice
crystals= smooth texture

sugar

surrounding the ice cream container with a 8:1 ice/salt mixture.

Question 20

What is the purpose of agitation in icecream? What happens when there is lack of agitation?

what is overrun? what is the desirable level in icecream, for frothiness, sherbets, and home-cranked icecream.

Answer 20

Stirring during freezing helps control aspects of texture.
Agitation achieves a
comparatively uniform
temperature throughout
the freezing mixture. some of the fat globules coalesce.
Lack of agitation in still-frozen ice creams results in rather coarse ice crystals and very limited overrun.

The increase in volume due to the incorporation of air from agitation is overrun
 Desirable level in commercial ice creams is 70% - 80%.
 Frothiness is detectable when it approaches 100% .
 Sherbets usually have only about 30–40% overrun .
 Home-cranked ice cream rarely exceeds 50%.

Question 21

What is the purpose of fat and protein in ice cream? what are the sources of each?

Answer 21

Ice cream with a large amount of fat tends to be much smoother in
texture.
 The fat content of chocolate makes this a useful ingredient in
promoting a fine-textured ice cream.
 Protein provided by egg white or added milk solids also performs a
stabilizing function.

Question 22

How does heat affect milk and milk products

Answer 22

whey precipitates with prolonged heating. Higeher temperature= quicker denaturing
visual evidence= thin layer of precipitated protein at bottom of pan
scorching is main problem in milk
cookery
denaturation leads to scum in milk products
denatured proteins clump together

Question 23

enzyme action in milk

Answer 23

temperature and pH are essential for enzymes to work
clot is stronger at about 5.8 pH
should not be heated above 60°C (140°F).

Question 24

acid in milk

Answer 24

fruits or acidic vegetables used to reduce casein to the isoelectric point of pH 4.6 where it is most easily precipitated
acidic ingredients should be stirred carefully and heated as short as possible

Question 25

salts in milk

Answer 25

influence the stability of the proteins can complicate the problem of heating meats in milk—as meats naturally contain some salts.  Cured meats have considerable added salt—likely to result in formation of milk curds during cooking

Question 26

effects of heat on cheese products

Answer 26

Moisture, fat content, and pH of natural cheeses, influence their ease of use in heated products.  The longer the heating period and the higher the temperature, the greater the detrimental changes.  Stringiness, toughness, and fat separation, etc.  Presence of an emulsifier helps avoid fat loss and consequent increased concentration of protein.

Question 27

What can and cannot be used to make foams? hint( fluid milk, evaporated milk, nonfat dried milk solids) pros and cons of each

Answer 27

Proteins and water in milk can be extended into thin films by agitation.These thin films enclose small air bubbles, making a foam in which the protein and water provide the continuous network of the colloidal dispersion, and the air is the discontinuous or dispersed phase. In fluid milks, protein concentration is too low to permit production of a foam with any stability.  Evaporated milk can be whipped into a foam with a very large volume.  Of limited usefulness unless a stabilizer is added.  Nonfat dried milk solids can also be used.  Limited stability from the comparatively high concentration of denatured milk proteins.

Question 28

Whipping cream, with its fat content of at least 30%, can be beaten to a foam—especially if chilled.  36% cream beats quickly to a more stable foam.  Overbeating of whipped cream causes reversal to a water-in-oil emulsion—butter.  Cream that has aged for about three days whips somewhat better than very fresh cream.  A result of the slight drop in pH during this period.  Sugar often is added to whipped cream for flavor.  Despite the slight negative effect it has on stiffness.

Question 29

Composition of muscle

Answer 29

water 75% protein 18%: (thick)myosin, (thin) actin, and tropomyosin Fat 4-10% carbohydrate little more than 1%: glycogen, glucose, glucose 6-phosphate Vitamins, minerals, and trace amounts myosin and actin associate into myofilaments then these associate with larger structures until complete muscle is defined

Question 30

What four categories of materials are abundant in connective tissue of meats What is collagen? What is tropocollagen?

Answer 30

Collagen (most important) ; elastin; reticulin; ground substance. All are either pure protein or conjugated protein compounds.  Collagen is the fibrous protein found in the structural sheaths within and between muscles it contains strands of tropocollagen which are produced by cells then moved to ground substance for the integration into molecules of collagen. Tropocollagen is a fibrous, coiled molecule consisting of three strands linked to make a long, thin unit. Planar rigidity of the pyrrolidine ring prevents bonding angles that lead to the usual α-helix & spherical nature of most food proteins. This rigidity is significant due to the large quantity of the two pyrrolidine-ring amino acids, proline and hydroxyproline.

Question 31

Describe elastin, ground substance and reticulin characteristics

Answer 31

Elastin found in limited amounts intramuscularly, is resistant to chemical change.  The yellow color distinguishes it from white collagen.  Ground substance is plasma proteins and glycoproteins in which fibrous molecules of collagen and and/or elastin are bound.  Reticulin is a fibrous protein similar to collagen.

Question 32

What does connective tissue consist of?

Answer 32

designated the endomysium (innermost), consists primarily of ground substance and collagen and is found between each fiber.

Question 33

Fish flesh is structurally similar to that of _______  Actin and myosin levels are ______ in fish than in red meats.  The_______ and _____in fish are more sensitive to heat.  These characteristics dictate the need for careful ________ control when preparing fish.

Answer 33

red meats. higher actomyosin and collagen temperature

Question 34

Lipids occur in muscle tissue & fatty deposits or fat depots. Which are the most abundant?

Answer 34

Triglycerides found most abundantly:  Oleic (18:1)  Palmitic (16:0)  Stearic (18:0)

Question 35

What affects the color or pigment in meats? what causes the intense red? brownish red?

Answer 35

Two key pigments responsible for meat color are hemoglobin and, more prominently, myoglobin(purple-red).(Iron-containing pigments with heme as the common component) The iron atom in the center of heme can complex with other atoms or compounds to form new compounds result in color change. Other color changes can be due to changes in valance of the iron atom itself. Intense red is from the presence of air myoglobin adds two atoms of oxygen to form OXYMYOGLOBIN Brownish red is from limited oxygen or long exposure to fluorescent or incandescent lightened this forms METMYOGLOBIN

Question 36

What is the name of the reddish orange pigment in salmon and cooked crustaceans? What causes meat to turn grayish brown?

Answer 36

Astaxanthin continued heating converts oxymyoghobin into denatured global hemichrome which is gray-brown

Question 37

How does heating affect the color of fish? poultry?

Answer 37

Heating enhances the light color of fish by increasing opacity.  Poultry is essentially colorless when cooked.  If subjected to intense heat it may develop a reddish-pink color.

Question 38

How are meats cured? function of nitrite? What is the key pigment in cured meats? What hastens the breakdown of pigment in cured meats? What reaction causes cured meat to turn brown?

Answer 38

cured to preserve them for long-term storage— usually with nitrates or nitrites nitrite prevents botulism. Nitric oxide myochrome: pinkish-red color. Exposure to light and additional oxygen hastens pigment breakdown Nitrosyl-hemochrome forms during curing, when a nitroso group joins with myoglobin, and heat denatures the globin portion of the molecule. On oxidation of the iron in nitrosyl-hemochrome, the pigment structure changes to denatured globin nitrosyl-hemochrome, which is brownish.

Question 39

slaughter to rigor mortis elapsed time biochemical processes continue several hours after slaughter and influence meat quality

Answer 39

fish: 1-7 hours (unless stored in ice) Chicken: 4 hours or more Turkey: 12 hours or more Pork: 1 day or more Beef: 11 days or more

Question 40

What does pH have to do with rigor mortis and meat quality? When does bacterial spoilage start? when should cooking or freezing begin so the flesh isn't tough? Describe the onset of rigor mortis in poultry vs fish

Answer 40

The pH reac hed during rigor mortis is about at the isoelectric point of the proteins. Causes fibers to pack together and force out some of the water. only after rigor mortis has passed. until rigor mortis has passed, Onset of rigor mortis usually is somewhat slower in poultry than in fish.

Question 41

Ways to achieve tenderness in meats? What is cold shortening? What influences color of beef and pork during aging period

Answer 41

chilling to retard rigor mortis in poultry and fish When meat is chilled too rapidly after slaughter, the muscles contract drastically—cold shortening. electric stimulation of carcasses 100-600 volts hanging carcasses so muscles are stretched past the normal resting state. Prior to the onset of rigor. pH-Dark-cutting beef: dark, sticky beef in which the pH dropped to only 6.6.

Question 42

Describe desirable storage conditions during aging:

Answer 42

Ultraviolet light to control growth of microorganisms.  Controlled humidity of 70%.  Temperature just above freezing.

Question 43

What are carcass/case ready meats?

Answer 43

Case-ready meats are prepared and packaged in large facilities in which safety is monitored carefully.  Hazard Analysis and Critical Control Points (HACCP) procedures are approved for each facility.  Packaging materials and techniques are constantly studied to extend the retail shelf life.  To help keep meat costs down.  Labor costs are kept to a minimum with case ready meats due to efficiencies in labor.

Question 44

What happens when meats are heated

Answer 44

Fat melts and proteins are denatured when meats are heated, water is also lost. MUSCLE FIBERS undergo changes in dimensions as a result of heating. MUSCLE PROTEINS in meat become less tender when heated. Some SHRINKAGE occurs during roasting, causing the ends of the bones to be more visible than they were before being heated. ELASTIN is not modified, but COLLAGEN molecules slowly change when subjected to moist heat. Hydrogen bonds begin to break between the component tropocollagen strands.  Conversion of collagen to gelatin has a great effect on tenderness of cuts heated for a long period. As when preparing less tender cuts.

Question 45

Heating effects on fish

Answer 45

Only a small amount of collagen occurs in fish, which means that the major effect of heating is change in muscle proteins. By heating fish just until it flakes, some collagen softening occurs—for easy separation of fibers.  Some denaturation of the muscle proteins also occurs.  Continued heating increases toughness, the result of continuing detrimental changes in the proteins.

Question 46

What is dry heat's effect on meat? Types?

Answer 46

Dry heat maximizes the quality of muscle proteins, rather than considering the changes in collagen if heating were extended longer.  Roasting; broiling & pan broiling, pan & deepfat frying. Broiling, grilling, or roasting produces meats that are juicier and have a better texture than results from deep-fat frying.

Question 47

What is moist heat's effect on meat? Types? What cuts of meat are suited for moist heat? which aren't? Why? What cooking types can be used to prepare fish? How long should cooking time be? How does a slow cooker compare to a pressure saucepan? Effect of roasting bags and foil wrapped roasts

Answer 47

Moist heat—braising or stewing—allows sufficient time for collagen to convert to gelatin. Without toughening muscle proteins unduly. The liquid in which the meat is braised or stewed prevents the surface of the meat from becoming hot enough to dry and brown excessively. Cuts high in CONNECTIVE TISSUE are suited to moist heat cooking due to their high collagen content.  TENDER CUTS are not well suited—their high amount of muscle protein is toughened by the heat.  POACHING OR STEAMING can be used to prepare fish. Cooking time needs to be just long enough to coagulate the muscle proteins. Meats prepared in a SLOW COOKER are palatable & more tender than if a pressure saucepan is used. FOIL AND BAGS= less pleasing in flavor, also less juicy and tender.

Question 48

What are cooking losses? How does wrapping affect cooking losses? slow cooker vs faster cooking methods? Temperature?

Answer 48

the combination of evaporative and drip losses—both juices and melted fat. foil or film wrapping causes greater cooking losses  Cooking losses are greater for meats prepared in a slow cooker  The higher the final temperature of meat, the greater is the cooking loss.

Question 49

Effect of pH on meat

Answer 49

Adding an alkaline ingredient darkens the color of the meat by increasing pH. Minimally influencing hydration.  Increased tenderness does not develop Marinating a less tender cut in undiluted vinegar for two days can result in increased juiciness and tenderness.  When the meat is braised.  Possible negative effects on aroma, flavor, and acceptability may offset improved tenderness and juiciness.

Question 50

Effect of salt on meat

Answer 50

enhanced water retention.  This ability to hold water improves juiciness.  The overall impact of salt on palatability is too minor to outweigh the health advantage of avoiding use of excess salt.

Question 51

Meat tenderizers vs mechanical tenderizing most popular tenderizers, names of enzymes, mechanical methods and purposes

Answer 51

Proteolytic enzymes can increase the tenderness of less tender cuts of meat.  The most common of these is a commercial blend of enzymes from papaya and salt.  Referred to simply as papain.  The three enzymes in this substance are chymopapain, papain, and a peptidase. Other proteolytic enzymes also can be utilized for this purpose.  Bromelain, an enzyme found in fresh pineapple.  Ficin, a proteolytic enzyme in figs. tenderizers with needles or blades to cut some of the connective tissue.  Does not produce the mushy character sometimes found in cuts tenderized by enzymes.  Other means of mechanical tenderization are pounding with a meat hammer, and cubing.  The ultimate means is a meat grinder.