Meat science and meat hygiene in the USA Flashcards
What makes wagyu beef so expensive?
The fat content
- ______ leads the world in beef production
whereas - _____ leads in poultry meat & pork production
- USA leads the world in beef production
whereas - China leads in poultry meat & pork production
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)
75% of meat cell is ?
Water
Connective tissue (collagen, elastin) decide?
Whether meat is tender or tough when you chew it
Sarcoplasmic protein function to?
Include aerobic & anaerobic metabolic enzymes, myoglobins
Myofibrillar protein exist in?
What are tehy?
Cytoplasm
Myosin, actin, other. They are contractile proteins.
When we are eating meat, we mainly eat?
Myofibrile proteins
What is water holding capacity?
?
What is the role of myosin in meat?
MY meat is so juicy, flavorful, and hydrates me!
Has role in meat
1. juiciness
2. Flavor
3. water-holding capacity of meat
5% of fat also exists in muscle cells
Beneficial role of lipids in meat?
My lips are so juicy, flavorful, and tender
1. tenderness,
2. juiciness &
3. flavor
Bad role of lipids in meat?
1. ______ taste if there is too much fat &
2. impaired _____-holding capacity of meat.
rancid, water
Low levels of intramuscular fat results in
1. ____ meat with _____ taste.
2. Hence, consumers prefer _______ or ______ marbled meat
dry, little, slightly, moderately
Ash 1%
- The heme iron from meat is more readily
absorbed as a nutrient, and heme iron accounts
for 40–60% of the total iron. - Calcium, magnesium, sodium, and potassium are
directly involved in contraction in living muscle, - whereas magnesium and calcium contribute to
muscle fiber contraction post-mortem
Composition of muscle varies from species to species
Cod has essentially no?
Lipids
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
connective and fat tissues.
muscle, fibers, connective
endomysium, perimysium, epimysium
Within the muscle cells/fibers,
1. the ____________ occupy nearly the entire intracellular volume.
2. The contractile unit of the muscle fiber is the ___________
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
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
has thousands of nucleuses, ER, mitochondria
A single muscle cell you have?
Myofibrils in the form of “stick”
When we are eating meat, we are eating these myofibrils.
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.
- 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
How many types of deaths are there?
- Somatic death –> immediate
- Cellular death –> they do not die soon, because they have glycolysis in the absence of oxygen can survive up to 4 hours.
During somatic death,
- Brain stops regulating the body
- Heart stops circulating blood
- Lung stops pumping oxygen
- Immune system stops body surveillance
What are the Normal biochemical changes during post-mortem
for conversion of muscle to meat?
- Lack of nutrient supply (glucose & oxygen) to cells…….aerobic metabolism stops
- Decline in body temperature (due to heat loss from dead body > heat gain)
- 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
Muscle stiffness in live animals is?
Tetanus
Muscle stiffness in dead animals is?
Rigor mortis
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
Color change during post-mortem in meat
Red meat = myoglobin
poultry/seafood = muscle is white
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)
DFD stands for?
Dark, firm, dry meat
Low lactic acid production makes PSE meat. What does PSE stand for?
PSE = meat is water, exudative. Pale, soft, and exudative.
- 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
- 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.
Glycogen and pH affect meat quality
Abnormally persistent ____ pH
(lack of _______) = DFD
or
A rapid drop in pH of meat = ___
high, glycogen, PSE
What are the four stages of rigor mortis?
The onset and completion of rigor mortis vary
with the
size, age, and species of animals
A. Endogenous enzymes:
1. cathepsins &
2. calpains
destroy ____, _____, ____, to speed up the rigor mortis
CT, myosins, actins
B. exogenous enzymes:
The most widely used enzymes are _________, known as cysteine endopeptidases
- derived from plants such as?
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)
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)
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)
Catheptic enzymes destroys _________ _________ tissue of the muscle and cause:
____________ of meat during aging.
Catheptic enzymes destroys collagenous
connective tissue of the muscle and cause:
tenderization of meat during aging.
What are the Three methods of storing meat for aging/ripening?
- Chilling room
- Pack them a vaccuum sealed bag.
- Or both in combo can be used
How do you grade meat so it is sold at the right price?
- Marbling (fat) distribution
- Texture of the muscle bundles. If the bundles, whether they are fine, coarse, or medium
- Color - dark, firm, dry, pale, soft, exudative = poor
- Maturitiy of the animal, whether producing meat from old or young animal
- 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
Which is considered to be a fine type of meat here?
12 because of the dat
There are ___ grades of meat in the US.
8
The last 3 grades in the US are not good quality. Name these grades.
Utility, cutter, canner
The last 3 grades of meat are used in?
sausage
What about the last 3 grades of beef make it bad?
- shows too much signs of age
- too little intramuscular fat in the meat
too little marbling - too low quality for cooking on its own
- usually sold to be used as an ingredient
in industrial food processing factories
e. g. hotdogs, dog food, etc
Left to right, age of animal increases
Moving away from prime to poorest quality
Fat (3-7.3%) is responsible for all good things in meat
such as palatability, juiciness, tenderness, and flavor
Meat Quality is generally described by 4 terms
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
Meat grading and quality are based on many factors. The way we are handling, transporting, slaughtering, preserving the meat all factor into quality.
Nutrition and social environment are also very important
