Marination and safety of meat

Question 1

Role of acid in marination

Answer 1

Reduces pH to increase myofibrillar spacing and increase WHC
Increases proteolysis by enzymes to weaken muscle structure
Increase conversion of collagen to gelatine

Question 2

What are other materials used for marinades?

Answer 2

Salt and phosphates
Water
Hydrocolloids
Flavourings

Question 3

How does myofibrillar protein solubilisation occur?

Answer 3

Salt causes protein to migrate to surface
Protein becomes denatured with heat
Causes coagulation and gel formation
Entraps the moisture

Question 4

How does papain and bromelain work as enzymes?

Answer 4

Cleaves peptide bonds and hydrolyses collagen and actomyosin

Question 5

Dry marinades use

Answer 5

Easy
Low penetration
Good on tender meats

Question 6

Wet cure use

Answer 6

Injection
Less time than dry methods

Question 7

Pastes use

Answer 7

Easy
Good crust

Question 8

What are the 2 types of tenderisation?

Answer 8

Mechanical and injections

Question 9

Use of injections

Answer 9

Precise and uniform
Economical

Question 10

What is mechanical tenderising?

Answer 10

Tumbling and massaging under vacuum

Question 11

What are the drivers of meat colour?

Answer 11

Myofibrillar levels
Haemoglobin and cytochromes
Myoglobin is the main component as it stores and delivers oxygen

Question 12

What is myoglobin?

Answer 12

Iron containing protein which causes red meat

Question 13

Why is red meat high in myoglobin?

Answer 13

Longer periods of activity

Question 14

Why is white meat low in myoglobin?

Answer 14

Limited activity and anaerobic

Question 15

What are the 3 types of myoglobin?

Answer 15

Deoxymyoglobin
Oxymyoglobin
Metmyoglobin

Question 16

Traits of deoxymyoglobin

Answer 16

Non-oxygenated
Ferrous iron
Dark purple

Question 17

Traits of oxymyoglobin

Answer 17

Oxygenated
Ferrous iron
Bright red as meat is cut

Question 18

Traits of metmyoglobin

Answer 18

Oxidised
Ferric oxidised iron
Brown colour

Question 19

How does curing effect myoglobin?

Answer 19

Forms nitroso myoglobin and nitrosylhemochrome

Question 20

What does spoiled meat form?

Answer 20

Sulfmyoglobin and ferrihemochrome when cooked

Question 21

When can meat become contaminated?

Answer 21

Slaughter and washing
People and equipment
Additional ingredients

Question 22

Why is fresh muscle-based food more risky?

Answer 22

Water activity, substrates and pH is compatible for microbes

Question 23

How does heat effect water?

Answer 23

Myofibrillar denaturation causes contraction and exerts force on water (decreases WHC)

Question 24

At what temperatures does collagen denature and become gelatine?

Answer 24

Denatured at 65C and changed at 95C

Question 25

What are the ingredients used for curing?

Answer 25

Nitrates and nitrites Salt and sugar Polyphosphate

Question 26

When is nitrate converted to nitric oxide?

Answer 26

By microbial enzyme endogenous in meat to form nitrite then to nitric oxide

Question 27

How does meat become pink during curing?

Answer 27

Nitric oxide binds to metmyoglobin

Question 28

Why is nitrite important during curing?

Answer 28

Protects against clostridium botulinum

Question 29

What is the role of ascorbic acid, sodium ascorbate and sodium erythorbate?

Answer 29

Colour development, prevent oxidation of pigments and reduce nitrosamines

Question 30

What are the 2 types of smoking?

Answer 30

Wood and liquid smoke

Question 31

How does fermentation occur?

Answer 31

Carbohydrates are converted to lactic acid at the right temperature

Question 32

How is drying used in sausages?

Answer 32

Removal of moisture from outside layer, drives water from inside to outside to prevent case hardening

Question 33

What are the steps of sausage manufacture?

Answer 33

Meat comminution, add water (50% ice), seasonings and rusk

Question 34

How does the protein interface effect sausages?

Answer 34

Solubilised protein creates thin layer around cut fat particles Denatures then prevents fat separation during cooking Thickness and composition determines stability

Question 35

How are myofibrillar proteins different to sarcoplasmic?

Answer 35

High emulsifying ability

Question 36

What is the gelling element in a sausage?

Answer 36

Collagen is surface active and is converted to gelatine which melts on heating and gels when cooled

Question 37

What casings can be used for sausages?

Answer 37

Natural: animal intestines, permeable and expandable Artificial: cellulose, collagen, minimises contamination Peelable: smoked and coagulated films

Question 38

How does under comminution time effect sausages?

Answer 38

Larger fat droplets Insufficient protein solubilised Thin interface Collagen at interface

Question 39

How does over comminution time effect sausages?

Answer 39

Small fat droplets Insufficient protein to stabilise interface Fat droplets coalesce Protein damage Collagen at interface