Meat color is very important because it affects consumer purchase decisions Research continues to find ways to improve the length of time a product stays bright red in the meat case The protein responsible for meat color is myoglobin ID: 1030361
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1. Meat ColorANSC 3404
2. Meat ColorMeat color is very important because it affects consumer purchase decisionsResearch continues to find ways to improve the length of time a product stays “bright red” in the meat caseThe protein responsible for meat color is myoglobin
3. Meat ColorDependent on Pigment content Ultimate pH and rate of pH decline postmortem Nature of group attached to the iron and the state of the iron Ingredients, processing, packaging
4. Meat Color – Pigment ContentPigmentsTwo main pigments: myoglobin and hemoglobinMajority of color is due to myoglobin
5. MyoglobinAccepts oxygen from hemoglobinStores oxygen for use by the living muscleContains a globin protein attached to a porphyrin ring containing a heme ironNature of the group attached to the iron, and the state (covalent or ionic) of the iron determines meat color
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7. DeoxymyoglobinDMb, Fe++No O2 presentOxymyoglobinOMb, Fe++Atmospheric O2 present+ O2MetmyoglobinMMb, Fe+++Low O2 partial pressureCarboxymyoglobinCOMb, Fe++CO present- O2 – e- + O2 Ensymatic Reduction (MRA) + O2 – e- + CO
8. DeoxymyoglobinOccurs when no ligand present for binding 6th siteHeme Fe is Ferrous (Fe++) Uncut MeatOnly water present to bind Very low oxygen tension requiredTypically associated with Vacuum PackagingConsumer acceptance of vacuum packaged products?Purplish-red or purplish-pink color
9. OxymyoglobinHeme Fe is Ferrous (Fe++) Cut meat exposed to O2No change in iron’s valence6th binding site occupied by diatomic oxygenDistal histidine interacts with bound O2Requires 40 torr partial pressure of O2 (5.25%)Alters structure and stabilityBright Cherry Red colorAs exposure increases-OMb penetrates deeperHigh O2 maintains OMb, but may induce Oxidation reactionsUnstable formationElectron availabilityStability depends on continuing supply of O2 Oxidative Metabolism enzymes rapidly use O2
10. MetmyoglobinOxymyoglobin is very unstable Oxidation of ferrous (Fe2+) Mb to ferric (Fe3+)Reasons for Formation of MMb:O2 levels of 0.2-1.3%Complete Oxygen Consumption Cellular respirationLow partial pressures of O2 (5-10mm/ 2.6-5.3%)Low MMb reducing ratesLow Oxygen transmission ratesSurface contamination Aerobic bacteria use up O2Brown ColorSurface Discoloration MMb located between superficial OMb and interior DMbgradually thickens and moves to surface
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12. Factors Affecting Meat ColorAmount of myoglobin in the muscleAge: Veal<Calf<Young beef<Old beefLooses affinity for oxygen as age increasesSpecies: Pork<Lamb<BeefType: Support<Locomotive
13. Age classMyoglobin contentVeal2 mg/gCalf4 mg/gYoung beef8 mg/gOld beef18 mg/gQuantity of Myoglobin
14. SpeciesColorMyoglobin contentPorkPink2 mg/gLambLight red6 mg/gBeefCherry red8 mg/gSpecies Differences of Myoglobin
15. Fiber Type Differences Muscle Fiber TypeCharacteristicsREDWHITEOxidative metabolismGlycolytic metabolismMyoglobin contentReddnessCapillary densityNumber of MitochondriaMitochondria sizeLipid contentGlycogen content Fiber diameterContraction speedFatigue resistanceContractile actionZ disk widthHigh LowHigh LowHigh LowHigh LowLow HighHigh LowLarge SmallHigh LowHigh LowLow HighSmall LargeSlow FastTonic PhasicLarge Small
16. Factors Affecting Meat ColorChemical State of MyoglobinFerrous (Fe++)H2O Purple DeoxymyoglobinO2 Red OxymyoglobinNO Unstable pink Nitric oxide myobglobinCO Red CarboxymyoglobinFerric (Fe+++) H2O (globin) Brown MetmyoglobinH2O (denatured globin) Brown/gray Denatured metmyoglobinSH Green SulfmyoglobinH2O2 Green Choleglobin
17. Color changes
18. Sulfmyoglobin and Choleglobin
19. Factors Affecting Meat ColorVitamin E feeding of cattlePrevents oxidation; retards conversion of myoglobin to metmyoglobinBacteriaProduce metmyoglobin, choleglobin, and sulfmyoglobin pigmentsCuringNitrosylhemochromogen is the stable cured meat pigment
20. Vitamin E
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22. Factors Affecting Meat ColorPre-Harvest StressExposure to long-term or short term stressEffects glycogen content of muscle and ultimate pH of muscleLong Term Stress: DFD (dark cutter)Transport, Hunger, Fear, AggressionUltimate pH above 5.9 (beef), 6.5 (pork)Short Term Stress: PSE Usually only problematic in pork Ultimate pH below 5.4Generally problem can be overcome with enhancement
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24. Factors Affecting Meat ColorPackaging