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Year 3 > Meat Processing, fish > Flashcards

Meat Processing, fish Flashcards

1
Q

Give some methods of preserving meats

A 
Chilling
Freezing
Heat processing
Curing
Smoking
Packing
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2
Q

What is pasteurisation?

A

Relatively mild heat treatment, reduces the total microbial load without changing the nature of the food severely

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3
Q

What is canning?

A

Sealing the food in an air-tight container (eg tin can), and then heating to high temperatures to destroy the majority of micro-organisms
Effective in extending the shelf life

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4
Q

What temperature should meat be frozen to?

When should meat not be frozen?

A

Below -18oC (most of the water is converted to ice crystals)

Merat should not be frozen before rigor mortis sets in

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5
Q

Why do frozen meats gradually spoil?

A 
Enzymatic activity (change in flavour)
Oxygen reacts with fat -> rancidity 
Surface dehydration (freezer burn)
The faster the freeze, the smaller the ice crystals -> less damage to structural properties of meat
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6
Q

Give the 4 techniques for freezing meat

A

Air blast freezing
Plate freezers
Immersion of spray freezers
Cryogenic freezing

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7
Q

What is the aim of chilling meat?

A

Reduce the temperature without causing formation of ice crystals, and to extend the shelf-life while causing minimal change to flavour, appearance or nutritional value
Reduces enzyme activity, slows growth and multiplication of pathogenic bacteria, extends shelf-life

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8
Q

What temperature must lamb and beef not got below?

A

Must not go below 10oC for the first 10 hours to avoid cold shortening

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9
Q

Which 2 gases are used in packaging?

A

N2 and CO2
Produce carbonic acid -> reduces surface contamination, acts as a weak organic acid (affects enzyme availability)
CO2 retards the growth of mould and aerobic bacteria
N2 acts as an inert gas filler to prevent pack collapse

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10
Q

Describe post-mortem glycolysis

A

Glycogen -> glucose -> lactic acid

pH drops from 7.0 to 5.5 (inhibits microbial growth)

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11
Q

When does rigor mortis occur?

A

9-12 hours after death

Maximum rigidity is attained 24 hours after death

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12
Q

Give some ante-mortem factors that affect meat quality

A 
Species/breed
Age
Sex
Environment
Nutrition
Disease
Stress
Pre-slaughter conditions
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13
Q

Give some post-mortem factors that affect meat quality

A 
Slaughter technique (eg insufficient bleeding will lead to problems with appearance and quality)
Storage conditions
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14
Q

What temperature should white meat be chilled at?

What about red meat?

A

White: 4oC
Red: 7oC

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15
Q

What is the problem with meat having a high sugar content?

A

Increased risk of fungal growth

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16
Q

How can meat be made more tender?

A 
Electrical stimulation immediately after slaughter
Mechanical tenderising (machines/tools)
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17
Q

Why is meat smoked?

What are the two processes?

A 
Aids preservation (phenolic compounds from the smoke are bactericidal)
Develops flavour
Cold smoking (up to 33oC)
Hot smoking (up to 90oC)
18
Q

How is meat cured?

What are the 3 methods?

A

2-6% salt, nitrite

19
Q

Which bacteria are used in fermentation?

A

Bacteria that produce lactic acid

20
Q

What is MAP?

A

Modified Atmosphere Packing

21
Q

What is Mechanically Recovered Meat (MRM)?

A

Meat with the texture of a puree, which has been obtained by mechanical means from residual material (muscle, connective tissue, bone, fat) of any species
Used as a ‘filler’ in burgers

22
Q

What percentage of CO2 will inhibit the growth of mould?

A

10% CO2

23
Q

Give the 3 kinds of heat treatments and give an example of a meat product that undergoes each one

A

Pasteurisation in water or steam at temperatures 100oC, usually in pressurised steam autoclaves (canned meats). Can be stored without refrigeration.

24
Q

Give some factors that affect fish spoilage rates

A 
Size (small fish= faster spoilage)
Post-mortem pH (high pH= faster spoilage)
Fat content (fatty= faster spoilage)
Skin properties (thin skin= faster spoilage)
25
Q

Give the 3 kinds of decomposition that affect fish

A

Bacterial
Enzymatic
Oxidative

26
Q

How does enzymatic spoilage of fish occur?

A

Stiffness of fish decreases -> protein degradation by enzymes (autolysis) -> pH increases
Proteins break down -> favourable conditions for bacterial growth

27
Q

Describe the 4 phases of fish spoilage

A

Phase 1: 0-5 days (autolytic changes caused by enzymes)

  • Sweet, seaweedy, delicate taste
  • Little deterioration

Phase 2: 5-10 days (autolytic changes caused by enzymes)

  • Significant loss of odour and flavour
  • Flesh is neutral, texture still pleasant

Phase 3: 10-14 days (bacteriological changes)

  • Fish begins to show signs of spoilage
  • Strong off-flavours, unpleasant smells

Phase 4: >14 days (bacteriological changes)
-Fish is spoiled and putrid, inedible

28
Q

How do you assess freshness of fish?

A

Appearance of eyes, gills, skin
Colour of gills and cavity
Discolouration
Presence/absence of rigor mortis

29
Q

How does stress affect meat quality?

A

Stress affects metabolism of glycogen in muscles
Affected meat doesn’t taste or keep well
Acute stress: pale, soft, exudative (PSE)-pigs
Chronic stress: dry, firm, dark (DFD)-beef

Chronic stress depletes available glycogen
Acute stress increases metabolic activity (thus depletes glycogen)

30
Q

What is the purpose of stunning?

A

Renders animal immediately insensitive to pain

31
Q

What are the phases of stunning?

A 
Tonic phase (very short in pigs)
Clonic phase (involuntary kicking movements)
Recovery?
32
Q

What are the 3 methods of stunning?

A

Mechanical
Electrical
Chemical (CO2 or inert gases eg argon)

33
Q

What are the 2 kinds of stunning using a captive gun?

A

Invasive: impact with skull produces stun, penetration of brain prevents recovery
Non-invasive: impact with skull produces stun

34
Q

What are the physical signs of an effective mechanical stun?

A 
Animal collapses
No rhythmic breathing 
No corneal reflex
Fixed, glazed expression 
Relaxed jaw, possibly with tongue hanging out
35
Q

What is the problem with high frequency stunning in poultry?

A

If over 100Hz, heart attacks are not induced so bird doesn’t die

36
Q

Give the signs of an effective electrical stun in poultry

A 
Arched neck with head held vertically
Eyes open
Wings held tight against body
Constant rapid body tremors
No rhythmic breathing
Rigidly extended legs
37
Q

Give some pros and cons of electrical stunning in poultry

A

Pros: Rapid, cheap
Cons: Proportion of birds are not stunned
High frequency stunning does not kill birds

38
Q

Give some pros and cons of gas stunning in poultry

A

Pros: minimal handling of birds, no live shackling, improved health and safety of person handling the birds, no possibility of missing stunner/inadequate stuns, improved carcass quality
Cons: more expensive, potential danger of leaks

39
Q

What is the maximum journey time (hours) for cattle, calves, pigs, piglets, sheep and lambs travelling in a basic standard vehicle?

A

8 hours

40
Q

Who is responsible for enforcement relating to ABP within slaughterhouses and cutting plants?

A

FSA

41
Q

Whose job is it to control and inspect ABPs?

A

Veterinary officer

Year 3 (28 decks)

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