Lab 7 Meat Product And Alternative

Question 1

Meat

Answer 1

Animal tissues suitable to use as food. Can be sub-divided in red meat, poultry, and seafood. Composed of 3 tissues: muscle tissue (lean part of meat), connective tissue, and adipose tissue (fat). These weren’t designed to be eaten but to perform a specific function. In order to produce quality food it’s important to understand muscle origin, function, and composition.

Question 2

Skeletal muscle

Answer 2

In general meat is comprised of skeletal muscle (or voluntary muscle) and the organs of the muscular system that are connected (directly or indirectly) to bones. Meat may also contain some smooth (component of blood vessel) of cardiac muscle. Each skeletal muscle is covered with a thin connective issue. These muscles are forms by muscle bundles that are constituted of muscle fibres which are forms by many myofibrils which, in turn, are formed by delicate myofilaments.

Question 3

Skeletal muscle content

Answer 3

Skeletal muscle typically contains:
45-75% water
15-20% protein
And 4-10% fat

They also contain small amounts of carbohydrates. (Glycogen), vitamins, minerals, and trace amounts of various organic compounds.

Question 4

Connective tissue proteins

Answer 4

Role of connective tissue is to connect and hold various parts of the body together.

Question 5

Connective tissue proper

Answer 5

Connective tissue that surrounds muscles, muscle bundles and muscle fibres.

Question 6

Collagen

Answer 6

The most abundant protein (glycoproteins) in the animal body. It significantly influenced tenderness. Collagen fibres are colourless and inextensible. When they aggregate they are white and upon cooking then to gelatin. It is the major component of tendons and ligaments. The distribution of collagen is not uniform among skeletal muscles, but the amount present generally parallels their physical activitys. For instance, muscles of limbs contain more collagen than muscles around the spinal column. This is because they are designed for different purposes, not necessarily because they are doing more work.

Question 7

Gelatin

Answer 7

What collagen becomes when cooked.

Question 8

Elastin

Answer 8

A connective tissue that’s much make abundant than collagen. Yellow and rubbery protein present in ligaments and arterial walls as well as in the framework of some organs including muscles. Elastin fibres are easily stretched and when tension is released they return to their original length. It is highly insoluble due to its high content of non-polar amino acids and desmosine cross links (unique amino acid in elastin). Elastin is highly resistant to digestive enzymes and no cooking method has any appreciable solubilizing effect on it. Therefore it contributes little or nothing or nutritive value of meat.

Question 9

Meat colour

Answer 9

Muscles can be classified as red or white, mainly based on their colour intensity which is due to their proportion of red end white fibres. Chicken leg muscles are darker due to more red fibres, chicken breasts are more white due to more white fibres. This colour difference is due to the concentration of the pigment myoglobin in the muscle and red fibres contains more myoglobin.

Question 10

Myoglobin

Answer 10

Red muscles contains more myoglobin. Myoglobin is not always red however, the difference in colour depends on the presence of oxygen and oxidative state of the iron atom in the myoglobin. Myoglobin is purple red when the iron is in the ferrous (Fe+2) state and free of additional atoms or compound. When meat is fresh and protected from contact with air it exhibits purple-red color is myoglobin.

Question 11

Oxymyoglobin

Answer 11

In presence of air myoglobin readily adds two oxygen atoms to form oxymyoglobin. This new form has a intense red.

Question 12

Metmyoglobin

Answer 12

Oxidation of myoglobal iron (from ferrous to ferric (+3)) discolours fresh meat and promotes the formation of Metmyoglobin, a brownish red pigment.

Question 13

The high tensile strength and insolubility of Collagen fibers is due to?

Answer 13

The insolubility and high tensile strength is due to intermolecular cross-linkages. These cross-linkages are fewer in number, and more easily broken, in young animals. As the animals. As the animal grows older, the number of cross-linkages increases and the linkages are converted to stable linkages. Coincidently, collagen is more soluble in young animals and become less soluble as animal ages

Question 14

The formation of Metmyoglobin is accelerated by:

Answer 14

1) bacteria contamination
2) high temperature
3) ultraviolet light
4) freezing
5) some metals and salt

Question 15

Factors that affect myoglobin content of red fibres

Answer 15

Myoglobin quantity in red fibres varies with species, age, sex, muscle, and physical activity.

Question 16

Flow chart for reduced myoglobin to oxymyoglobin to Metmyoglobin

Answer 16

Reduced myoglobin (purple):
- oxygenates to oxymyoglobin (bright red)

Oxymyoglobin (bright red):

• deoxygenation to reduced myoglobin (purple).
• oxidation (electron loss) to Metmyoglobin (brown)

Metmyoglobin (brown):
- reduces (electron gain) to reduced myoglobin (purple)

Question 17

Effects of heating myoglobin (cooking meat)

Answer 17

Heat changed the pigments when meat is cooked. The myoglobin present in the interior of muscles is transformed to oxymyoglobin. Confirmed heating converts the oxymyoglobin into denatured globin hemichrome, the grayish brown associated with well-done meats.

Question 18

How cooking certain meats changes them.

Answer 18

Heating enhances the light color of fish by increasing opacity, it this is not dramatic change. Poultry ordinarily is essentially colorless when cooked. If young poultry has been frozen and some hemoglobin (ligament of blood) has leaked from the marrow, there may be some hemoglobin on the flesh close to the bones, which becomes dark when cooked. Sometimes poultry subjected to very intense heat develops reddish-pink color. This is result of hemoglobin reacting with carbon monoxide and nitric oxide generated by an electric heating element or flames when barbecuing.

Question 19

Curing

Answer 19

Either nitrates or nitrites are added to preserve meats for long term storage, while preventing the growth of Clostridium botulinum. The nitric oxide which forms from nitrates and nitrites in meat curing combined with myoglobin to eventually form nitric oxide myochrome which contributes to the stability of the familiar pinkish-red color. Curing agents impart colour and flavour to foods such as bacon, wieners, ham, and deli meats.

Question 20

How does exposure to light affect meat.

Answer 20

Exposure of light causes oxidation of ferrous iron to ferric III (Fe3+), which results in development of brownish color.

Question 21

Postmortem changes

Answer 21

Hours after death of an animal, a very important biochemical processes occurs: glycogen converted to lactic acid. This is a very desirable process because the pH of the meat drops from approximately neutral (pH 7) to pH of about 5.5 in red meat and 6.2-6.5 in fish. However this post-Mortem lactic acid production only occurs if the animal was in a rested, comparatively calm state at the time of slaughter. If an animal survived a stress of sufficient duration to deplete its glycogen reserve just prior to slaughter the pH of the muscles will not drop because of little post-Mortem lactic acid is formed. The resultant high pH causes dark, firm and dry muscle.

Question 22

Freezing of meat

Answer 22

Freezing is recognized as excellent method to preserve meat. However dorm deterioration (rancidity, discolouration) continues to occur in meat even at freezer storage temperatures. In addition quality of frozen meat is influenced by freezing rate, length of freezing, freezer storage conditions (temperature, humidity) and packaging material used. For frozen storage of meat. With proper packaging most meat can be frozen for 6-12 months. Ground beef up to 3 months.

Question 23

Thawing of meat

Answer 23

Thawing process does greater damage to meat than freezing. Main reason is thawing occurs more slowly than freezing and because the temperature rises rapidly to the freezing point and then remains there for the entire course of thawing. This allows the formation of new large ice crystals, and increases microbial growth and chemical changes. To prevent such problems, it is recommended to thaw meat at refrigerator temperatures. Of course this is a slow process that might require several days for large times such as turkeys or ham.

Question 24

Meat preparation

Answer 24

When meat is heated, fat softens and melts, proteins are denatured, muscle tissues shrinks and coagulates, and water is lost. When heat is applied meat primarily changed in two opposing ways; muscle fibres toughen and connective tissue become more tender. The denaturation of muscle proteins makes meat tougher because upon heating to 40-50C, myosin becomes less soluble and hydration of myosin and other muscle proteins decreases.

Question 25

Connective tissues when cooking

Answer 25

Elastin is not modified, but collagen molecules slowly change when subjected to moist heat and form gelatin. Conversion of collagen to gelatin had considerable effect on tenderness of meat cuts that are heated for an extended period, as is form when preparing less tender cuts of meat. The length of time that meat is held above 65C is important in promoting collagen conversion to gelatin. So if collagen content is high, extended heating is desirable to permit considerable conversion of collagen to gelatin. This tenderizing action will more than compensate for the toughening of muscle proteins that is occurring at the same time. However, tender cuts of meat will become less tender with extended heating if the meat reaches temperature above 60C. This effect is the result of the toughening of muscle proteins, a change that cannot be offset by the conversion of limited amounts of collagen to gelatin. The importance of the opposing effects of collagen and muscle proteins during heating is seen particularly clearly in fish, which means that the preparation of fish. 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 becomes flakes, some softening of collagen occurs to permit easy separation of fibres while some denaturation of muscle proteins also occurs. At this point, the fish flesh is still tender. Continued heating beyond this point results in increasing toughness and dryness.

Question 26

Dry heat

Answer 26

Dry hear methods (roasting, broiling) are designed to rapidly cook meat to maximize quality and juiciness of muscle proteins and do little to transform collagen to gelatin. Tender cuts of meat, because of their relatively high proportion of muscle protein and reduced quality of collagen are well suite to dry heat cooking.

Question 27

Microwave cooking

Answer 27

Microwave cooking of meat is essentially a dry heat method. The heating that occurs when food is subjected to microwaves is caused by the rapid vibration of water, some fat, or sugar molecule in the food. It is important to note that microwaves only penetrate as far as 4cm into the food.

Question 28

Moist heat

Answer 28

Moist heat (braising, stewing) is designed to provide sufficient time for collagen to be converted to gelatin without toughening the muscle proteins. The liquid in which the meat is cooked prevents the surface of he next from becoming hot enough to dry and brown excessively. Cuts that are high in connective tissue are well suite to this type of meat preparation. Poaching or steaming can be used to prepare fish, but the preparation time needs to be just long enough to coagulate the muscle proteins.

Question 29

Cooking losses

Answer 29

Cooking losses are the combination of evaporation and drip loss. Because of both relatively high cost of meats and the reduced juiciness associated with losses during cooking, the effects of the cooking methods on cooking losses and the resulting impact on yield are important. Predictably, the higher the final temperature of meat, the greater is the cooking loss.

Question 30

Effect of acid

Answer 30

Acid may tenderize meat by catalyzing the hydrolysis of collagen. This reaction depends on the pH of the acid and the length of contact between the meat and the acid. Marinating a less tender cut can result in increased juiciness and tenderness.

Question 31

Enzymatic tenderizeration

Answer 31

Commercial meat tenderizers contain proteolytic enzymes, such as papain, that can be used to increase the tenderness of less tender cuts of meat. The powdered enzyme preparation will penetrate to distance of only 2mm so that it tenderizes only the surface of the meat. Forking does help but may not distribute the enzyme uniformly. The enzyme exhibits maximum activity between 55-80C so that the longer it is held at this temperature the greater the hydrolysis of the muscle fiver and collagen. Beyond 80C the enzyme is inactivated. Enzyme tenderized meat usually shows increase cooking loss and increased dryness. Over-tenderization will result in a dry mealy texture.

Question 32

Mechanical tenderization

Answer 32

Commercially, meat can be run through a tenderizer equipped with needles or blades to cut some of the connective tissue and increase tenderness. This makes it possible for some less tender cuts to be used in form say as tender cuts. Mechanical tenderization changes the texture somewhat, but it does not produce the mushy character sometimes found in cuts tenderized by enzymes. Another means of mechanical tenderization is pounding to break some of the muscle fibres and connective tissue.

Question 33

Evaluation of meat quality.

Answer 33

Determined by sensory and/or instrumental methods. Evaluation of quality considers the following: appearance, flavor, tenderness, juiciness. High quality cooked meat should have an attractive appearance, not shriveled and dry. It should be tender, moist, and have a pleasant odour and flavour characteristic of the type of meat.

Question 34

Tenderness

Answer 34

Tenderness is measured subjectively by the response to the initial bite and amount of chewing required. A tender cut of meat cooked by dry heat is usually soft, whereas a less tender cut of meat cooked by moist heat tends to be stringy due to the hydrolysis of collagen between muscle fibres. It is important in evaluating tenderness to compare pieces of the same size from the same area. The tenderness may be evaluated objectively using an instrument such as the Instron Warner-Bratzler Shear.

Question 35

Juiciness

Answer 35

Juiciness is evaluate with respect to mouthfeel of the meat. Can also be measured objectively by calculating the percentage cooking loss. The amount of weight loss during cooking is dependent on:
extent of muscle shrinkage, resulting moisture loss, the loss of fat, and hydrolysis.
The juiciness of braised meat may be improved by costing the meat with flour and then browning in fat. This procedure forms a crust which reduced the amount of moisture loss from the meat during braising. The meat also Browns more quickly, reducing the exposure to high temperatures and so preventing toughening of the muscle protein.

Question 36

Textured soy/vegetable Protein (TSP or TVP)

Answer 36

Meat substitute made by extrusion from defatted soy flour; containing ~ 70% proteins.

Question 37

Instron Warner-Bratzler Shear

Answer 37

A universal materials instrument that measured the force required to shear a sample.

Question 38

Seafood products (Fish)

Answer 38

Fish may be fresh, smoked, frozen, canned (mackerel, sardines, etc.), dried, pickled, or salted.
Fresh fish may be sold as: whole, dressed (entrails, gills, head, tail, and fins removed), steaks (cross-sections), fillets (lengthwise cuts).

Question 39

Seafood produced (others)

Answer 39

A variety of fabricated seafood such as crab legs and flakes, based on Japanese surimi process technology, are also on the market. Surimi is made from mechanically deboned fish that has been washed to remove such substances as fat and pigments and stabilized to improve the frozen shelf life. Flavours, colours, starch, and/or egg whites are added to the surimi paste which is then extruded into shapes that resemble shellfish. Worldwide consumption of fish and seafood is an important source of protein in diets. An inexpensive way of increasing omega-3 fatty acids in a diet is by consuming mackerel and sardines.

Question 40

Pulses (meat alternatives)

Answer 40

Legumes are edible peas or beans (seeds) of a double-seamed seed pod of the leguminasae plant family. Legumes are also called pulses and include beans, peas, lentils, and peanuts. An alternative source of plant protein, they are a significant source of nutrients including protein, iron, various B vitamins, folic acid, and starch or oil. Legumes are low in fat, contain no cholesterol and are a good source of fiber. While pulses are generally high in protein (20% - 25% protein by weight) they do not contain all of the essential amino acids. In soy protein, methionine is the limiting essential amino acid. In many diets pulses are commonly consumed with grains (deficient in lysine) to form a compete diet of protein.

Question 41

Cooking of pulses.

Answer 41

Due to their structure of the mature legume seed, dry beans and other pulses require cooking in water to soften the cotyledon cell walls and gelatinize starch granules. The seed coat of dried beans and whole peas to become fully hydrated and softened, soaking in water for several hours or overnight prior to cooking is recommended. Pre-soaking reduces in water by 25% or more. Lentils and split peas are cooked without prior soaking in water to assist in rehydration. Many of these beans are also available fully cooked, and then canned or frozen.

Question 42

Soy protein

Answer 42

Soybeans, a legume, are processed into oil, tofu, soy flour and texturizing vegetable protein (TVP), also known as textured soy protein (TSP). Soy protein is made from dehulled, defatted soybean meals. The concentration of proteins are mainly soluble carbohydrates and some nitrogenous substances and minerals. Due to this process much of the undesirable beany flavour is removed and the soy protein concentrated have a bland taste.

Question 43

3 types of soy protein

Answer 43

Soy protein isolate
Soy protein concentrate
Textured soy protein

Question 44

Soy protein isolate

Answer 44

The most refined form of soy protein and is mainly used in meat products to improve texture and eating quality. Soy protein isolate contains 90% protein.

Question 45

Soy protein concentrate

Answer 45

Basically soybean without water soluble carbohydrates. Soy protein concentrate contains about 70% of protein and is used predominantly in food industry. A main ingredient in meat analogs it is used to bind water and emulsify fat.

Question 46

Textured soy protein (TSP)

Answer 46

Made from soy protein concentrate, 70 % protein with added processing to produce texture. It is available as dry flakes or chunks. TSP will keep its structure when hydrated and hydrated texture soy protein chunks have a texture similar to ground beef. TSP is used in food manufacturing as a replacement for meat in entrees, as an ingredient in the production of meat analogues, or as filler in processed meat products. Today newer naturally concentrated products are available on the market with improved flavour. Some examples include soy burgers and hot dogs, bacon/bacon bits, and meat analogies including pizza pepperoni, deli slices and ground round (Yves Veggie Ground Round).

Question 47

Meat analogues

Answer 47

Most meat analogues are made from soy protein, some are made from tofu (a soybean curd) but products can also be made from seitan, the protein portion of wheat or gluten. The mild neutral flavour of TSP and seitan can easily adopt flavours and seasonings added during preparation.

Question 48

Braise

Answer 48

Cook slowly in covers utensil in a small amount of liquid using low heat for lengthy period of time. Meat is typically seared or browned first for better colour and flavour. It is ideal for less tender, more economical cuts of meat.