Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

VPH - Animal By-products and Food Technology > Muscle to Meat > Flashcards

Muscle to Meat Flashcards

You may prefer our related Brainscape-certified flashcards:
Gourmet Food flashcards
1
Q

Post-mortem changes in meat

A

Exanguination leads to collapse of circulation
No oxygen is available
Energy comes from CP and anaerobic glycolysis - production of lactic acid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is rigor mortis

A

Muscle stiffening and loss of extensibility after ATP is exhausted

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What causes rigor mortis

A

ATP is depleted so myosin heads irreversibly bind to actin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Phases of rigor mortis

A

Delay phase
Onset phase
Completion phase
Resolution phase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Delay phase

A

Muscle gets energy from CP and anaerobic glycolysis
Causes lactic acid build up - lowers pH of meat

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Onset phase

A

ATP is exhausted and extensibility reduces

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Completion phase

A

Irreversible binding of actinomyosin bonds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Resolution phase

A

Proteolytic enzyme action

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Pre-slaughter factors affecting rigor mortis

A

Stress depletes muscle glycogen stor
Leads to early rigor and high muscle pH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Post-slaughter factors affecting rigor mortis

A

Excessive chilling causes severe shortening - tough meat
Electrical stimulation can accelerate rigor without excessive shortening

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Other factors affecting rigor

A

Fibre type composition - Determines ATP production/consumption
Fast muscle is prone to PSE - more glycogen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

When does resolution occur

A

After a variable period of time

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How does resolution occur

A

Two endogenous proteases:
Calpains
Cathepsins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What inhibits calpains?

A

Calpastatins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What inhibits cathepsins?

A

Cystastatin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What happens during ageing?

A

Proteins are broken down into amino acids and fats then into aromatic fatty acids (glutamic acid, inosinic acid)

17
Q

Risks of prolonged ageing

A

Rancidity due to fat oxidation

18
Q

What is tenderness

A

Eating/physical quality
Expressed in terms of:
Shear force
Myofibrillar fragmentation index (MFI)
Taste/eating quality assessment

19
Q

What influences tenderness?

A

Age - older animals have more collagenous tissue
White meat is less tender than red
Amount of shortening during rigor

20
Q

What is cold shortening?

A

When muscle cools below 10 degrees BEFORE rigor mortis starts
Due to excessive release of Ca from SR in presence of ATP

21
Q

Prevention of cold shortening

A

Keep beef/lamb >10 degrees for first 10h
Keep pork >10 degrees for first 3h

22
Q

Electrical stimulation

A

Within 1 hr of slaughter
Causes muscle contraction
Accelerates pH fall
Depletes ATP
Induces early rigor
Prevents cold shortening
Improves meat tenderness
Fractures sarcomeres and activates proteases

23
Q

How do you suspend bovine carcasses?

A

By obturator foramen to stretch premium muscles (longissimus dorsi)
Makes meat more tender

24
Q

Methods of improving tenderness

A

suspend cattle from obturator foramen
Needle/blade tenderisation
Papain from papaya
Bromelin from pineapple
Ficin from pigs
Marination
Electrical stimulation

25
Q

How does pattern of acidification affect meat quality?

A

Rapid acidification = PSE
Slow acidification = DFD

Affected by pre-slaughter handling of animals

26
Q

What is PSE?

A

Pale Soft Exudative Meat
Abnormally pale
High drip loss
Lower water holding capacity
Tough
Caused by rapid acidification

27
Q

What is DFD?

A

Dark Firm and Dry meat
Abnormally dark
Rapid spoilage
Tender
High water holding capacity
Caused by slow acidification

28
Q

What is water holding capacity?

A

pH of meat influences extent muscle proteins are changed
Most proteins lose change between pH 5.1-5.5
(In this range muscle release water)
Isoelectric point is 5.2

29
Q

What causes the bright red colour

A

Oxidation of myoglobin to oxymyoglobin (Blooming)

30
Q

Why does DFD not turn bright red

A

High water holding capacity so reduced oxygen penetration
No oxygenation of myoglobin

31
Q

What causes paleness in PSE?

A

Enhanced protein denaturation
Increase in conversion to metmyoglobin

32
Q

How do you assess colour of meat?

A

Minolta colour meter

33
Q

Which is more succulent?

A

DFD

34
Q

How can you improve succulence

A

Increase fat content

35
Q

What is boar taint?

A

Unpleasant urine-like odour of uncastrated boars caused by sex steroids deposited in IM fat

36
Q

Prevention of boar taint

A

Castrate males
Slaughter younger
slatted floors to reduce faecal contamination
Avoid overcrowding

37
Q

How is carcass quality assessed?

A

Weight
Conformation
Fatness

VPH - Animal By-products and Food Technology (12 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions