Marination and safety of meat Flashcards
Role of acid in marination
Reduces pH to increase myofibrillar spacing and increase WHC
Increases proteolysis by enzymes to weaken muscle structure
Increase conversion of collagen to gelatine
What are other materials used for marinades?
Salt and phosphates
Water
Hydrocolloids
Flavourings
How does myofibrillar protein solubilisation occur?
Salt causes protein to migrate to surface
Protein becomes denatured with heat
Causes coagulation and gel formation
Entraps the moisture
How does papain and bromelain work as enzymes?
Cleaves peptide bonds and hydrolyses collagen and actomyosin
Dry marinades use
Easy
Low penetration
Good on tender meats
Wet cure use
Injection
Less time than dry methods
Pastes use
Easy
Good crust
What are the 2 types of tenderisation?
Mechanical and injections
Use of injections
Precise and uniform
Economical
What is mechanical tenderising?
Tumbling and massaging under vacuum
What are the drivers of meat colour?
Myofibrillar levels
Haemoglobin and cytochromes
Myoglobin is the main component as it stores and delivers oxygen
What is myoglobin?
Iron containing protein which causes red meat
Why is red meat high in myoglobin?
Longer periods of activity
Why is white meat low in myoglobin?
Limited activity and anaerobic
What are the 3 types of myoglobin?
Deoxymyoglobin
Oxymyoglobin
Metmyoglobin
Traits of deoxymyoglobin
Non-oxygenated
Ferrous iron
Dark purple
Traits of oxymyoglobin
Oxygenated
Ferrous iron
Bright red as meat is cut
Traits of metmyoglobin
Oxidised
Ferric oxidised iron
Brown colour
How does curing effect myoglobin?
Forms nitroso myoglobin and nitrosylhemochrome
What does spoiled meat form?
Sulfmyoglobin and ferrihemochrome when cooked
When can meat become contaminated?
Slaughter and washing
People and equipment
Additional ingredients
Why is fresh muscle-based food more risky?
Water activity, substrates and pH is compatible for microbes
How does heat effect water?
Myofibrillar denaturation causes contraction and exerts force on water (decreases WHC)
At what temperatures does collagen denature and become gelatine?
Denatured at 65C and changed at 95C
What are the ingredients used for curing?
Nitrates and nitrites
Salt and sugar
Polyphosphate
When is nitrate converted to nitric oxide?
By microbial enzyme endogenous in meat to form nitrite then to nitric oxide
How does meat become pink during curing?
Nitric oxide binds to metmyoglobin
Why is nitrite important during curing?
Protects against clostridium botulinum
What is the role of ascorbic acid, sodium ascorbate and sodium erythorbate?
Colour development, prevent oxidation of pigments and reduce nitrosamines
What are the 2 types of smoking?
Wood and liquid smoke
How does fermentation occur?
Carbohydrates are converted to lactic acid at the right temperature
How is drying used in sausages?
Removal of moisture from outside layer, drives water from inside to outside to prevent case hardening
What are the steps of sausage manufacture?
Meat comminution, add water (50% ice), seasonings and rusk
How does the protein interface effect sausages?
Solubilised protein creates thin layer around cut fat particles
Denatures then prevents fat separation during cooking
Thickness and composition determines stability
How are myofibrillar proteins different to sarcoplasmic?
High emulsifying ability
What is the gelling element in a sausage?
Collagen is surface active and is converted to gelatine which melts on heating and gels when cooled
What casings can be used for sausages?
Natural: animal intestines, permeable and expandable
Artificial: cellulose, collagen, minimises contamination
Peelable: smoked and coagulated films
How does under comminution time effect sausages?
Larger fat droplets
Insufficient protein solubilised
Thin interface
Collagen at interface
How does over comminution time effect sausages?
Small fat droplets
Insufficient protein to stabilise interface
Fat droplets coalesce
Protein damage
Collagen at interface
