ADSC 2010 Lecture 9 Outline of Last Lecture I Meat Color Continued A Deoxy myoglobin B Oxy myoglobin C Met myoglobin D Chart E Vacuum packaged meats F Vitamins G Cured Meats Outline of Current Lecture I Meats Proteins 1 Myofibrillar Proteins a Myosin and Actin b Troponin and Tropomyosin 2 Stromal or Connective Tissue Proteins a Collagen b Elastin II Meat Lipids A Muscle Fat III Meats Nutritive IV Meats Acceptability 1 Tenderness 2 Juiciness 3 Flavor Aroma 4 Appearance 5 Price V Meat Value Determinants A Carcass Weight B Carcass Category and Grade a Beef 1 Yield 2 Quality Current Lecture I Meats Proteins Continued 1 Myofibrillar proteins salt soluble Myosin and actin contractile 75 Make up majority of muscle structure and contraction in meat Troponin and Tropomyosin main regulatory proteins Attach with actin Reg actin and myosin interact ion during muscle contraction Both each make up 5 of myofibrillar Close contact with actin and myosin filament 2 Stromal or Connective tissue proteins acid soluble Fiberglass Connect hold various parts of body together and distributed throughout body as components of skeleton Attaches skin hide Infections II III Wound healing Collagen major protein in body 25 30 weight White color High tensile strength highly ordered structure complex protein Elastin Yellow color Very strong ELASTIC Mainly in tendons and ligaments Repro tract blood vessels abdominal wall Sarcoplasmic myofibrillar stromal biggest effect on tenderness Solubility less soluble as you go up Meats Lipids adipose tissue A Muscle Fat About 50 of dietary energy comes from fat Animal fat highly digestible 97 Much of flavor of meat comes from fat carbonyl compounds Species flavor Animal fat generally more saturated than plant Solid at room temp Order of saturation level pork beef lamb In monogastrics dietary fat can influence the saturation level of carcass fat Can get soft and oil i e when pigs eat peanuts Meats Nutritive In one 3 oz serving of meat Calories 10 RDA Protein 40 RDA Iron 16 RDA Zinc 35 RDA B Vitamins 40 RDA Poor source of vitamins a d e k c Poor Source of Calcium and Magnesium Meat protein has high Biological value All essential amino acids Most people eat 3 5 Servings Fat oils IV 1 3 Milk dairy 2 2 Meat eggs beans 2 Veggies 1 Fruit 5 1 Breads Meats Acceptibility Factors affecting consumer acceptability 1 Tenderness single most important factor 3 factors that impact tenderness a Myofibrillar contractile proteins Contraction due to rigor causes toughening Rigor stiffening due to death of muscle Aging causes increasing tenderness Muscle enzymes break down proteins and loosen structure 14 21 days b Connective mainly collagen Amount of connective tissue locomotor muscle Solubility as animals age solubility c Marbling intramuscular fat keeps tender Lubrication fat stimulates salivation which eases chewing Dilution fat dilutes the negative Methods for improving tenderness Electrical stimulation 60 500V Speeds rigor formation Blocks cold shortening Cause pH decline Physical disruption Aging structural breakdown by muscle enzymes Marinating acid solutions to solubilize connective tissues Tenderizers papain ficin bromelin CaCl2 NaCl PO4 Papin pineapple Mechanical Tenderization needle or blade tenderizers Proper cooking low temperature long time solubilizes collagen 2 Juiciness refers to liquid retention during cooking Three factors that affect juiciness a Marbling intramuscular fat contributes to juiciness b Cooking method rapid heat searing broiling seals in moisture c Added moisture Enhancement V 3 Flavor and Aroma Protein gives meat flavor nitrogenous compounds Fat gives species flavor beef pork lamb carbonyl components 4 Appearance major factor at point of purchase Color uniformity correctness firmness texture pH related problems normal pH of meat 5 6 Dark Firm Dry DFD predominately in beef Results in pH of 6 0 Long term stress Low muscle glycogen at slaughter Pale Soft Exudative PSE predominately in pork Results from low pH 5 4 Short term stress prior to slaughter 5 Price Chicken vs Beef Meats Value determinants Two main determinants of carcass value A Carcass weight Decreasing percentage hot carcass weight live weight x 100 Hot carcass no organs hair head feet OP HCW LW Pork 70 196 280 Beef 60 750 1250 Sheep 50 70 140 Factors affecting dressing percentage Fill contents of GI tract at slaughter Finish fatness fatter animals DP Muscling Heavier muscled animals have DP Hide head feet weight B Carcass Category or Grade Beef Evaluated between 12th and 13th rib 2 Grades Yield Grade and quality grades a Yield Grades 1 5 boneless closely trimmed retail product from chuck round rib and loin 12th rib backfat inch Ribeye area in2 Kidney Pelvic and heart fat of carcass weight Hot carcass weight pounds b Quality Grade Prime Choice Select Standard Maturity A E Bone size shape ossification Marbling score intramuscular fat content
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