Muscle to Meat

Question 1

Name the main steps of conversion of muscle to meat

Answer 1

Muscle
Slaughter
Blood supply ceases
Remaining energy used to allow muscle extensibility
When energy is depleted => rigor mortis
Without oxygen, glucose => lactic acid
pH 5.4-5.7
Meat

Question 2

Define rigor mortis

Answer 2

Muscle stiffening and loss of extensibility after death.

Question 3

Name the 4 stages of Rigor Mortis

Answer 3

Delay - 6-12 hours post mortem
Onset - when ATP is exhausted
Completion
Resolution - proteolytic enzymes come into action

Question 4

Name the pre-slaughter factors that can affect rigor mortis and how they affect it

Answer 4

Physical stress or disease
Depletes muscle glycogen store
Limited glycolysis => early RM and high muscle pH

Question 5

Name the post-slaughter factors which affect rigor mortis and how they affect it

Answer 5

Excessive rate of chilling => cold shortening (severe shortening) => tough meat

Question 6

What type of muscle is most prone to pale soft exudate, and which animals do NOT have these

Answer 6

Fast glycolytic muscles
Cattle and horses - not prone to PSE

Question 7

Name the endogenous proteases which play an important role in the resolution of rigor mortis, and what are they inhibited by

Answer 7

Calpains - inhibited by calpastatins
Cathepsins - inhibited by cystatin

Question 8

What does increased calpastatin cause

Answer 8

Inhibition of calpains
Leads to tougher meat

Question 9

What is a risk of prolonged ageing of meat

Answer 9

Can cause fat oxidation => rancid odour

Question 10

Name the 3 different ways tenderness can be expressed

Answer 10

Shear force
Myofibrilar fragmentation index (MFI)
Taste or eating quality assessment

Question 11

What are the positives and negatives of rapid chilling of meat

Answer 11

+ve = reduces microbial growth, evaporation and drip loss
-ve = risks cold shortening of the meat making it tough

Question 12

What conditions are required for cold shortening to take place

Answer 12

Cooling below 10 degrees C before rigor mortis sets in

Question 13

How to prevent cold shortening in beef/lamb and pork, and generally

Answer 13

Beef/lamb - not below 10 degrees in the first 10 hours
Pork - not below 10 degrees in the first 3 hours
Generally - electrical stimulation

Question 14

What can electrical stimulation induce in pork

Answer 14

Pale soft exudate

Question 15

Apart from electrical stimulation, name other methods to improve tenderness

Answer 15

Stretching the muscles - hip suspension
Needle/blade tenderisation
Papain, bromelin, ficin
Marination

Question 16

Name some properties of meat quality

Answer 16

Dark cutting beef/ Dark firm dry pork = not good
Pale soft exudate = bad
Water holding capacity
Succulence
Colour and paleness - paleness = bad
Boar taint = bad

Question 17

If acidification of meat is very rapid, what is the result

Answer 17

Pale soft exudate

Question 18

If the acidification of meat is very slow, what is the result

Answer 18

Dark, firm, dry meat

Question 19

What affects the water holding capacity of meat

Answer 19

pH - influences the extent that muscle proteins are charged, which is needed to hold onto water

Question 20

How able is dark, firm, dry meat able to hold onto water vs pale soft exudate

Answer 20

DFD - Higher water holding capacity
PSE - lower, high drip loss of water

Question 21

The paleness of meat is inversely proportional to pH - true or false

Answer 21

True

Question 22

What gives meat its colour

Answer 22

Myoglobin
Bright red colour in presence of oxygen is synonymous with freshness

Question 23

DFD pork and DCB dont “bloom” in presence of oxygen - true or false and why

Answer 23

True
High water holding capacity makes meat turgid and reduces oxygen penetration therefore no blooming

Question 24

What is “blooming” when talking about meat colour

Answer 24

The bright red colour in presence of oxygen

Question 25

What are the causes of boar taint

Answer 25

Sex steroids, like androsterone, deposited in intramuscular fat.

Question 26

Give 4 ways that boar taint is managed/prevented

Answer 26

1. Castration
2. Avoiding overcrowding
3. Slatted floors to reduce faecal contamination
4. Early slaughter of males.