Meat science and meat hygiene in the USA

Question 1

What makes wagyu beef so expensive?

Answer 1

The fat content

Question 2

• ______ leads the world in beef production
  whereas
• _____ leads in poultry meat & pork production

Answer 2

• USA leads the world in beef production
  whereas
• China leads in poultry meat & pork production

Question 3

Muscle cell (fiber) biology
 Composition of muscle
 Structural organization of muscle
 Physical and biochemical changes in muscle after
death (i. e. key steps in converting muscle to meat)

Question 4

75% of meat cell is ?

Answer 4

Water

Question 5

Connective tissue (collagen, elastin) decide?

Answer 5

Whether meat is tender or tough when you chew it

Question 6

Sarcoplasmic protein function to?

Answer 6

Include aerobic & anaerobic metabolic enzymes, myoglobins

Question 7

Myofibrillar protein exist in?
What are tehy?

Answer 7

Cytoplasm
Myosin, actin, other. They are contractile proteins.

Question 8

When we are eating meat, we mainly eat?

Answer 8

Myofibrile proteins

Question 9

What is water holding capacity?

Answer 9

?

Question 10

What is the role of myosin in meat?

Answer 10

MY meat is so juicy, flavorful, and hydrates me!

Has role in meat
1. juiciness
2. Flavor
3. water-holding capacity of meat

Question 11

5% of fat also exists in muscle cells

Question 12

Beneficial role of lipids in meat?

Answer 12

My lips are so juicy, flavorful, and tender
1. tenderness,
2. juiciness &
3. flavor

Question 13

Bad role of lipids in meat?
1. ______ taste if there is too much fat &
2. impaired _____-holding capacity of meat.

Answer 13

rancid, water

Question 14

Low levels of intramuscular fat results in
1. ____ meat with _____ taste.
2. Hence, consumers prefer _______ or ______ marbled meat

Answer 14

dry, little, slightly, moderately

Question 15

Ash 1%

1. The heme iron from meat is more readily
   absorbed as a nutrient, and heme iron accounts
   for 40–60% of the total iron.
2. Calcium, magnesium, sodium, and potassium are
   directly involved in contraction in living muscle,
3. whereas magnesium and calcium contribute to
   muscle fiber contraction post-mortem

Question 16

Composition of muscle varies from species to species

Question 17

Cod has essentially no?

Answer 17

Lipids

Question 18

Skeletal muscle consists of:
1. 10% of ?
2. 90% ______ cells/ ______ and _____ tissue is distributed at 3 levels/scales in muscle:
1. _________ = which surrounds each muscle fiber
2. _________ = which surrounds bundles of the muscle fibers,
3. ________ = which surrounds the muscle as a whole & it is an extension of tendon

Answer 18

connective and fat tissues.

muscle, fibers, connective

endomysium, perimysium, epimysium

Question 19

Within the muscle cells/fibers,
1. the ____________ occupy nearly the entire intracellular volume.
2. The contractile unit of the muscle fiber is the ___________

Answer 19

Within the muscle cells/fibers,
1. the myofibrils occupy nearly the entire intracellular volume.
2. The contractile unit of the muscle fiber is the sarcomere

Question 20

Muscle cells/fiber are:
1. multinucleated, and
2. spindle-shaped cells
3. 10 to 100 micrometers diameter
4. Elongated (i. e. long cell)
 a length that ranges from –> a few millimeters in fish
to several centimeters
in terrestrial animals

Answer 20

has thousands of nucleuses, ER, mitochondria

Question 21

A single muscle cell you have?

Answer 21

Myofibrils in the form of “stick”
When we are eating meat, we are eating these myofibrils.

Question 22

How does muscle contracts: mechanism?

Actin and myosin interact. Actin slides over myosin by using ATP, Mg, and Ca. To relax, ATP, Mg, and Ca also.

Answer 22

• Action potential (electric stimuli) from motor nerves for muscle contraction
• e. g. exercise or shivering (chilling)
  1. ATP
  2. Calcium
  3. magnesium
  4. Actin slides over myosin filaments via climbing and falling on to
  myosin for contraction and relaxation, respectively.
   ATP is required during both climbing and falling processing

Question 23

How many types of deaths are there?

Answer 23

1. Somatic death –> immediate
2. Cellular death –> they do not die soon, because they have glycolysis in the absence of oxygen can survive up to 4 hours.

Question 24

During somatic death,

Answer 24

1. Brain stops regulating the body
2. Heart stops circulating blood
3. Lung stops pumping oxygen
4. Immune system stops body surveillance

Question 25

What are the Normal biochemical changes during post-mortem
for conversion of muscle to meat?

Answer 25

1. Lack of nutrient supply (glucose & oxygen) to cells…….aerobic metabolism stops
2. Decline in body temperature (due to heat loss from dead body > heat gain)
3. Buildup of metabolic wastes in cells due to lack of removal of metabolic wastes by circulation
    e. g. lactic acid is normally transported from muscle cells to liver
   * Muscles must undergo different biochemical processes, which makes muscle to ripen (become meat).
    Key changes that occur in postmortem muscle is the development of rigor mortis, means stiffness of the muscle
    The primary cause of post-mortem muscle biochemical changes such as rigor mortis is a decline in the level of ATP

Question 26

Muscle stiffness in live animals is?

Answer 26

Tetanus

Question 27

Muscle stiffness in dead animals is?

Answer 27

Rigor mortis

Question 28

Normal biochemical changes during post- mortem for conversion of muscle to meat cont…
Anaerobic metabolism due to decline in energy source & oxygen
a. ATP level declines
b. Creatine phosphate (CP) level declines
c. Glycogen breakdown (glycolysis)

leading to?
5. Increase in lactic acid level in muscle cells
6. Decline in pH in muscle cells
7. Rigor mortis (muscle stiffening)
8. Proteolysis of muscles by lysosomal enzymes (muscle aging = meat ripening)
9. Color change in muscle

From purple ——-> to bright red or pink

Question 29

Color change during post-mortem in meat

Answer 29

Red meat = myoglobin
poultry/seafood = muscle is white

Question 30

Within 24 hours after death:
1. Glycogen ——> lactic acid
 Glycogen > 50 mmol/kg in live animals ——> <10 mmol/kg in meat
 lactic acid <10 mmol/kg in live animals ——> > 100 mmol/kg in meat
2. muscle pH: 7.0 ——> 5.6 (because of lactic acid)
3. muscle color (blossoms): purple changes to bright red or pink (pH 7.0 ——> 5.6)

Question 31

Question 32

DFD stands for?

Answer 32

Dark, firm, dry meat

Question 33

Low lactic acid production makes PSE meat. What does PSE stand for?

Answer 33

PSE = meat is water, exudative. Pale, soft, and exudative.

Question 34

1. dark, firm, and dry (DFD) meat is more common in cattle = is opposite to PSE because its pH remains 6.0.
   Such abnormally high pH causes meat darker in color, tough and susceptible for microbial growth
    Cause 1: starvation e. g. extended transport of cattle without feeding, depletes muscle glycogen.
    Cause 2: Beef Stress Syndrome, “Alarm” reaction of General Adaptation Syndrome (i. e. Fright = “fight
   or flight”)
    Limited lactic acid production occurs postmortem;
    hence, pH remains above 6.0 (i. e. does not decline)
    Solution: Feed and rest for 24 or 48 h prior to slaughter

Question 35

2. pale, soft, and exudative (PSE) meat is more common in pigs (hereditary)
    Very rapid glycolysis due to:
    excitement (ante mortem) or
    holding on kill floor a long time before chilling (postmortem)
    huge lactic acid production, leading to a rapid pH decline while the carcass temperature is still warm
    Abnormally pH reaches 5.2 in 2 h postmortem, which is by far below the ultimate pH 5.6 of meat
    Such abnormal pH causes meat
    loss of color, firmness, water-holding capacity.

Question 36

Glycogen and pH affect meat quality
 Abnormally persistent ____ pH
(lack of _______) = DFD
or
 A rapid drop in pH of meat = ___

Answer 36

high, glycogen, PSE

Question 37

What are the four stages of rigor mortis?

Answer 37

Question 38

The onset and completion of rigor mortis vary
with the

Answer 38

size, age, and species of animals

Question 39

A. Endogenous enzymes:
1. cathepsins &
2. calpains

destroy ____, _____, ____, to speed up the rigor mortis

Answer 39

CT, myosins, actins

Question 40

B. exogenous enzymes:
The most widely used enzymes are _________, known as cysteine endopeptidases
- derived from plants such as?

Answer 40

B. exogenous enzymes:
The most widely used enzymes are proteinases, known as cysteine endopeptidases
- derived from plants such as:
1. papain (papaya),
2. bromelain (pineapple),
3. ficin (fig)

Question 41

An ideal meat tenderizer would be a ________ ________ with specificity for ______ and ______ in connective tissue at the
1. low pH of meat which would act either at
 low (refrigerated storage) or high temperatures (cooking)

Answer 41

An ideal meat tenderizer would be a proteolytic enzyme with
specificity for collagen and elastin in connective tissue at the
1. low pH of meat which would act either at
 low (refrigerated storage) or high temperatures (cooking)

Question 42

Catheptic enzymes destroys _________ _________ tissue of the muscle and cause:
 ____________ of meat during aging.

Answer 42

Catheptic enzymes destroys collagenous
connective tissue of the muscle and cause:
 tenderization of meat during aging.

Question 43

What are the Three methods of storing meat for aging/ripening?

Answer 43

1. Chilling room
2. Pack them a vaccuum sealed bag.
3. Or both in combo can be used

Question 44

How do you grade meat so it is sold at the right price?

Answer 44

1. Marbling (fat) distribution
2. Texture of the muscle bundles. If the bundles, whether they are fine, coarse, or medium
3. Color - dark, firm, dry, pale, soft, exudative = poor
4. Maturitiy of the animal, whether producing meat from old or young animal

Question 45

• Good marbling means good quality = Marbling links to quality grades
  such as (moving from lesser to greater quality in that order):
  1. Prime
  2. Choice
  3. Selec

Question 46

Which is considered to be a fine type of meat here?

Answer 46

12 because of the dat

Question 47

There are ___ grades of meat in the US.

Answer 47

8

Question 48

The last 3 grades in the US are not good quality. Name these grades.

Answer 48

Utility, cutter, canner

Question 49

The last 3 grades of meat are used in?

Answer 49

sausage

Question 50

What about the last 3 grades of beef make it bad?

Answer 50

1. shows too much signs of age
2. too little intramuscular fat in the meat
    too little marbling
3. too low quality for cooking on its own
4. usually sold to be used as an ingredient
   in industrial food processing factories
    e. g. hotdogs, dog food, etc

Question 51

Answer 51

Left to right, age of animal increases

Moving away from prime to poorest quality

Question 52

Fat (3-7.3%) is responsible for all good things in meat
such as palatability, juiciness, tenderness, and flavor

Question 53

Meat Quality is generally described by 4 terms

Answer 53

Organoleptic qualities: (read this box)

You have to also look at nutritional or chemical composition.

Safety, does this meat contain biological, chemical and physical hazards? Even if very good marbling, if it contains those hazards –> reject it

Serviceability –> ability to be processed, prices

Question 54

Meat grading and quality are based on many factors. The way we are handling, transporting, slaughtering, preserving the meat all factor into quality.

Answer 54

Nutrition and social environment are also very important