Muscle to meat

Question 1

What theory is used to describe muscle contraction and relaxation

Answer 1

sliding filament theory

Question 2

what is the sliding filament theory supported by

Answer 2

molecular structure and interactions
myofribillar proteins

Question 3

describe myosin structure

Answer 3

large elongated
two regions

Question 4

describe the head region of myosin

Answer 4

globular
-pear shaped
-functional: actin binding site

Question 5

describe the tail region of myosin

Answer 5

rod
responsible for filament

Question 6

name of complex that resembles a string or pearls

Answer 6

actin-troponin-tropomyosin complex

Question 7

what is the Tn-C of the complex

Answer 7

caclium binding site

Question 8

what is the Tn-T

Answer 8

binding site with tropomysin

Question 9

what is the Tn-I of the complex

Answer 9

Inhibits ATP-ase

Question 10

what does the binding of calcium do to the complex

Answer 10

reveals a binding site for myosin

Question 11

describe the process of the complex

Answer 11

-Calcium ion binds to tropomyosin which exposes the myosin binding site on actin
-ATP binds to the myosin head
-mysoin detaches from actin
-ATP hydrolysis occurs which activate myosin head
-tropoyosin bind to site on actin and phophate disociates strengthening the bond between actin and myosin
-ADP disociates and myosin contracts pulling actin

Question 12

first step of muscle contraction/relaxtion event

Answer 12

nerve impulse transmitted via T-Tubules

Question 13

what are T-tubules

Answer 13

blanket that surrounds the myofibrils

Question 14

describe calcium’s role in contraction (steps 2 and 3 of the sequence)

Answer 14

sarcoplasmic reticulum releases Ca2+
Ca2+ binds to Tn-C

Question 15

What happens to the troponin complex after calcium is bound

Answer 15

changes position to reveal myosin binding site

Question 16

what is required for actin-myosin interaction

Answer 16

ATP

Question 17

why can muscle contract after death

Answer 17

ATP is still present in the muscle which can cause contraction

Question 18

Which respiratory cycles are not supported after slaughter

Answer 18

oxidative phosphorylation

Question 19

After death what does the muscle use for energy

Answer 19

glycogen and creatine phosphate stored in the muscle

Question 20

what does glycolysis without oxygen generate

Answer 20

lactic acid

Question 21

what does the production of lactic acid do to the meat

Answer 21

drop pH

Question 22

what happens once all the energy stores have been used

Answer 22

muscles stay contracted = maximum toughness

Question 23

process of glycogen to lactate

Answer 23

glycogen -> glucose-> pyruvate-> lactate

Question 24

what is the ultimate pH

Answer 24

final pH the tissue will reach

Question 25

at what pH is muscle near at death

Answer 25

7

Question 26

what is the rejection of the ultimate pH of lamb

Answer 26

<5.5

Question 27

what is the rejection of the ultimate pH of beef

Answer 27

>5.8

Question 28

characteristics of meat at a high pH

Answer 28

DFD dark firm dry

Question 29

characteristics of meat at low pH

Answer 29

PSE pale soft exudative

Question 30

what can cause a dark color in meat

Answer 30

stress before death

Question 31

rate and extent of pH fall is affect by what

Answer 31

intial glycogen in muscle pre-slaughter stress muscle fibre type temperture

Question 32

what is rigor mortis

Answer 32

stiffness of death

Question 33

when does rigor mortis occur

Answer 33

when all ATP is depleted

Question 34

what happens during rigor mortis

Answer 34

irreversible cross-bridges form between actin and myosin

Question 35

another name for pre-rigor meat

Answer 35

hot boned

Question 36

what is hot boned beef

Answer 36

when carcass is boned while warm and in pre-rigor state

Question 37

why is hot boned beef used for production of burgers and sausages

Answer 37

-it is often dark in color becuase endogenous enzymes have not been able to relax the meat -it has high WHC -lower eating quality

Question 38

how can toughness of rigor be resolved

Answer 38

aging

Question 39

how does aging resolve rigor

Answer 39

proteolytic enzymes hydrolyse myofilaments which caused release between actin and myosin= relaxtion

Question 40

types of proteolytic enzymes that resolve rigor

Answer 40

calpains cathepsins

Question 41

describe calpains

Answer 41

require Ca2+ and high pH -disrupts Z lines

Question 42

what pH are cathepsins active at

Answer 42

lower pH

Question 43

what is cold shortenign

Answer 43

excess contraction/shortening

Question 44

when does cold shortening occur

Answer 44

when pre-rigor meat is chilled too quickly (between 10 and 0C)

Question 45

effect on mea tof cold shrotenign

Answer 45

excess drip low WHC extremely tough

Question 46

mechanism of cold shortening

Answer 46

at low temp muscle is still alive with plenty of ATP and ph>6 -sarcoplasmic reticulum becomes leaky and Ca2+ leaks out to trigger contraction -calcium pump can no longer remove Ca2+ and muscle remains contracted

Question 47

why does DFD meat appear darker

Answer 47

light does not reflect off dry meat as well

Question 48

why does PSE meat have a light appearance

Answer 48

more light reflects or watery surfaces

Question 49

what causes the sfotness of PSE meat

Answer 49

protein denaturation at the low pH

Question 50

what is accelerated aging and conditioning of meat

Answer 50

treatment that allows for control over time and temp to reach rigor

Question 51

advantages to accelerated aging and conditioning

Answer 51

more consistent and tender meat avoids cold shortening

Question 52

what does accerlerated aging and condiitoning involve

Answer 52

the electrical stimulus of the carcass -controlling the cooling rate through strict temp and time regime

Question 53

what does accelerated aging and conditioning involve

Answer 53

the electrical stimulus of the carcass -controlling the cooling rate through strict temp and time regime

Question 53

what does accelerated aging and conditioning involve

Answer 53

the electrical stimulus of the carcass -controlling the cooling rate through strict temp and time regime

Question 54

what does accelerated aging and conditioning induce

Answer 54

induces rapid ATP hydrolysis -muscle enter rigor sooner so it can be chilled without shortening

Question 55

what does accelerated aging and conditioning involve?

Answer 55

the electrical stimulus of the carcass -controlling the cooling rate through strict temp and time regime

Question 56

what does accelerated aging and conditioning induce

Answer 56

induces rapid ATP hydrolysis -muscle enters rigor sooner so it can be chilled without shortening