ADSC 2010 Week 5 Notes
ADSC 2010 Week 5 Notes ADSC 2010
Popular in Intro to Animal and Dairy Science
Popular in Agricultural & Resource Econ
This 5 page Class Notes was uploaded by Neena Molavi on Sunday February 8, 2015. The Class Notes belongs to ADSC 2010 at University of Georgia taught by Dean Pringle in Spring2015. Since its upload, it has received 104 views. For similar materials see Intro to Animal and Dairy Science in Agricultural & Resource Econ at University of Georgia.
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Date Created: 02/08/15
MONDAY FEBRUARY 2 2015 Fresh meat color triangle Deoxymyoglobin no oxygen Fe H20 bound 0 Purple Oxymyoglobin Fe 02 bound 0 Bright red Metmyoglobin 0 Fe no site 0 Brown Deoxymyoglobin oxygenation blooming 1520 min9 oxymyoglobin oxidation9 metmyoglobin reduction9 deoxymyoglobin Deoxymyoglobin oxidation9metmyoglobin reduction oxymyoglobin reduction9deoxymyoglobin When you introduce oxygen it will bind where the water was bound 0 Myoglobin has a stronger affinity for molecular oxygen than for water If you dissolved vitamin c in water and put it on metmyoglobin meat it would go back to red o Antioxidants primarily vitamin C and E are reducing agents Cooking denatures myoglobin and produces brown color Cured meats nitrite interacts with myoglobin and forms a pink color cured meat color 0 N029 N0 gas 0 NO binds to free binding site Remember oxidation is LOSS of an electron reduction is GAIN of an electron Meats Proteins 1 Myofibrillar proteins salt soluble myo means muscle 0 Actin and myosin main contractile proteins Together they make up 75 of myofibrillar proteins 0 Troponin and tropomyosin main regulatory proteins work together to open the binding sites to allow interaction between actin and myosin or cover and close the binding sites calcium is the switch interacts with troponin and pulls tropomyosin off the binding site 2 Stromal or connective tissue proteins acid soluble marinate in orange juicelemon juicecitrus juice to combat them i Collagen is the major protein in the body 1 2530 of weight 2 White 3 High tensile strength 4 Has a negative impact on quality of meat ii Elastin 1 Yellow color 2 Very strong 3 Mainly in tendons and ligaments WEDNESDAY FEB 4 2015 Meats Lipids Muscle fat 0 About 50 of dietary energy from meat comes from the fat 0 Animal fat is highly digestible 97 0 Much of the flavor of meat comes from fat carbonyl compounds Species flavor 0 Animal fat is generally more saturated than plant Solid at room temperature Order of saturation level pork ltlt beef lt lamb n Digestive system 0 In monogastrics dietary fat can influence the saturation level of carcass fat Can get soft and oily carcasses Meats Nutritive Value Fats Oils 8 Sweets USE SPARINGLY Key 1 Fat natually occurring i Sugar and added added v51 These symbols show fat and v vquot v YA added sugars in foods Milk Yogurt Meat Poultry Fish amp Cheese Group Dry Beans Eggs 2 3 SERVINGS amp Nuts Group 23 SERVINGS Ve etable Fm Grgup Group 35 24 SERVINGS SERVINGS Bread Cereal 39 Rice amp Pasta V Group 611 SERVINGS 0 one 3 02 serving of meat provides 0 10 of RDA of calories 0 40 of RDA of protein 0 16 of RDA of iron Heme iron comes from meat myoglobin Nonheme iron comes from vegetables Heme iron increases absorption of nonheme iron into the body 35 of RDA of zinc 40 of RDA of Bvitamins poor source of vitamins A D E K and C 0 poor source of calcium and magnesium meat protein has high biological value Meats Acceptability Factors affecting consumer acceptability Tenderness single most important factor 0 Three factors impact tenderness Myofibrillar component contractile proteins a Contraction clue to rigor causes toughening Rigor stiffening clue to death of 000 muscle a Aging causes increased tenderness 0 Dry aging 0 Wet aging 0 Muscle enzymes break down proteins and loosen structure 0 1421 days of aging to optimize tenderness Connective tissue component mainly collagen n Amount of connective tissue locomotor muscles increase a Solubility as animal age increases solubility decreases FRIDAY FEBRUARY 6 2015 Meats Acceptability Marbling intramuscular fat 0 Lubrication fat stimulates salivation which eases chewing Dilution fat dilutes the negative myofibrillar and connective tissue effects on tenderness increases tenderness Methods for improving tenderness 0 Electrical stimulation 60500 V Mainly beef and lamb Speeds rigor formation a Rigor mortis myosin clamps downquot on actin when ATP is taken away death then 12 hours later that relaxes for cows n Electrical stimulation speeds up the process Blocks cold shortening n Meat gets too cold before it has finished rigor mortis Causes pH decline a Regular muscle has a pH of approx 7 n Meat has a pH of approx 56 Physical disruption 0 Aging structural breakdown by muscle enzymes 0 Marinating acid solutions to solubilize connective Ussue o Tenderizers papain ficin bromelin CaCl2 NaCl P04 0 Mechanical tenderization needle or blade tenderizers 0 Proper cooking low temperaturelong time solubilizes collagen Factors affecting consumer acceptability Juciness refers to the fluid retention during cooking 0 Three factors impact juiciness Marbling intramuscular fat contributes to juiciness Cooking method rapid heat searing or broiling seals in moisture n Cooking for too long takes out the moisture Addedinjected moisture enhancement 0 Flavor and aroma 0 Protein gives the meat flavor nitrogenous compounds 0 Fat gives the species flavor beef pork or lamb carbonyl compounds 0 Appearance 0 Major factor at point of purchasequot 0 Color uniformity correctness firmness texture 0 pH related problems normal pH of meat 56 0 Dark firm and dryquotDFDquot predominantly in beef results from High pH gt60 caused by a Long term stress a Low muscle glycogen at slaughter o Pale soft and exudativequotPSEquot predominantly in pork Low pH lt54 caused by a Short term stress prior to slaughter a High glycogen at slaughter n Exudative won t retain its natural juices Price 0 Chicken vs beef Meats value determinants Two main determinants of carcass value 0 Carcass weight Dressing percentage hot carcass weight live weight x 100 Hot carcass weight no skin no GI tract no hide General ranges n Pork 70 DP 196 HCW 280 LW n Beef 60 DP 750 HCW 1250 LW n Sheep 50 DP 70 HCW 140 LW Factors affecting dressing percentage n Fill content of the GI tract at slaughter n Finish fatness fatter animals have higher DP n Muscling heavier muscled animals have higher DP n Hide head and feet weight
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