Meat
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outline the nutritional values of meat
• high biological value • contains essential amino acids • source of vitamins and minerals • high in saturated FAs
what are the health related concerns of eating meat
• meat is energy dense and low in fibre • may lead to chronic diseases e.g cancer, CV disease • nitrites • food safety e.g salmonella. ecoli • antibiotic resistance
what are the environmental concerns of eating meat
• agricultural sustainability - animal welfare
what are the three layers of connective tissue
There are three layers of connective tissue: epimysium, perimysium, and endomysium.
what factors do protein and fat content vary with
age, breed, cut of meat
what are the three classifications of meat proteins?
stromal myofibrillar sarcoplasmic
what are the characteristics of stromal muscle cells
10-15% of the muscle made up of collagen, elastin and reticulin
what are the characteristics of myofibrillar muscle cells
55% of the muscle made up of actin and myosin
what are the characteristics of sarcoplasmic muscle cells
30% of the muscle made up of haemoglobin and myoglobin
what are the characteristics of collagen
white thin transparent insoluble triple helix structure
what are the characteristics of elastin
yellow does not degrade to geltin
what are the characteristics of gelatin
product of the reversible thermal denaturation of collagen used in jam, jelly, yoghurt, marshmallows
what are the three myofibrillar proteins
myosin actin desmin
what is myosin
long, filamentous, highly charged have a strong affinity for calcium and magnesium has two subunits
what is actin
globular actin forms filamentous actin involved in muscle contraction associated with troponin and tropomyosin
what is desmin
degrades during ageing can increase water holding capacity
what are the two subunits of myosin and what are their roles
light meromyosin- structural stability and muscle contraction heavy meromyosin- ATP binding
what are the sarcoplasmic proteins
enzymes - e.g calpaan, for tenderisation and flavour contribution pigments - e.g myoglobin, haemoglobin, for colour intensity and variation
what are the 3 types of myoglobin
deoxymyoglobin- Fe2+, no ligands, purple oxymyglobin- Fe2+, oxygen, bright red metmyoglobin- Fe3+, no ligands, brown
what are the 4 stages of muscle to meat after death
acidification onsent resolution conditioning
what are the three stages of rigor mortis
pre-rigor rigor post-rigor
outline the process of post-mortem acidification
animal dies and oxygen levels fall respiration and oxygen supply to muscles stop ATP is generated from glycogen by anaerobic glycolysis lactic acid accumulates and the muscle acidifies pH falls to 5.5
what is pale soft exudative meat?
-short term stress on the animal, low pH at the time of slaughter
what is dark firm and dry meat?
• long term stress on the animal, high pH at slaughter, produces better meat