AS 445 Test Question and Answers Updated

AS 445 TEST QUESTION AND ANSWERS UPDATED Muscle Composition ▪75% water ▪18% protein ▪3% lipid ▪1.5% non-protein N substances •Nucleotides (ATP & ADP), free Amino Acids, peptides ▪1% carbohydrates •Glycogen, glucose ▪1% ash •Iron, potassium, sodium, sulfur what can change muscle composition? age, finish, area of carcass (front vs back), species trimmings range Beef:50/50 - 95/5 Pork: all fat (80% chemical fat)- 90/10 Muscle Structure muscle --> Muscle bundle -->muscle fibers-->myofibrils--> sarcomere (actin and myosin) connective tissue used for jerky or ground -flat iron steak cut with grain to avoid CT Muscle Protein Classes 1. Myofibrillar: (contractile and structural) actin and myosin = salt soluble 2. sarcoplasmic: water soluble 3. stromal: connective tissue= collagen and elastin Myofibrillar Proteins - salt soluble 1. contractile: actin and myosin regulated by troponin and tropomyosin 2. structural: degraded during postmortem storage;- 'aging' = tenderness -titin, nebulin, desmin 80% of what we use Sarcoplasmic Proteins •Water-soluble •Mainly glycolytic enzymes •Myoglobin (Oxygen-binding protein inside muscle, Responsible for meat color, Darker color = more myoglobin, Heme (iron) group changes color with oxygen, oxidation, and during curing) important for cured products- myoglobin Stromal Proteins connective tissue 1. collagen (most abundant protein in mammals)- breaks down with slow moist cooking (major impact on meat tenderness) 2. elastin- doesn't break down (ligamentum nuchae) yellow tough, needs to be ground Water importance -largest % of meat -meat and non meat ingredient