The color of the meat didn't have much effect on the nutritional value of meat, but to some extent affect appetite and commodity value.If it is caused by microbial color changes affect the sanitary quality of meat.
1. The flesh of flesh color is essentially composed of myoglobin (Mb) and hemoglobin (Hb).Myoglobin pigment protein of meat itself, about the color depth and its content.Hemoglobin in the blood, the effect on meat color depending on whether bloodletting fully.Blood in the meat residue is more hemoglobin content, more deep color.Bloodletting fully nude is normal, bloodletting inadequate or not bleed (cold) slaughter flesh deep and dark.
2. The change of myoglobin muscle of eggs Bai Ben as purple, combines with oxygen to generate oxygenation myoglobin, bright red, is the symbol of fresh meat.Myoglobin and oxygenation myoglobin can be oxidized to generate high-speed myoglobin, brownish, make the color darker;Myoglobin and nitrite reaction can generate nitroso myoglobin, is bright red, is the typical color of bacon when heated.
3. The factors affecting muscle color changes
(1) the oxygen content in environment determines the content of oxygen in the myoglobin is MbO2 or MMb formation, which directly affect the color of the meat.
(2) the humidity environment humidity is big, the oxidation slowly, because of moisture in the meat surface, influence the diffusion of oxygen.If fast, low humidity and air velocity are accelerating the formation of the high-speed rail myoglobin, make the brown color is fast.Such as beef at 8 ℃ refrigerated, relative humidity is 70%, 2 d brown;Relative humidity is 100%, 4 d brown.
(3) the high temperature environment temperature to promote oxidation, low temperature oxidation more slowly.Such as beef 3 ~ 5 ℃ storage 9 d brown, brown at 0 ℃ storage 18 d.So in order to prevent the oxidation of the meat brown, as far as possible under the low temperature storage.(4) pH animal glycogen depletion before slaughter, the limit of the flesh after the rigor mortis pH is high, easy to appear abnormal physiological meat, beef DFD meat, the meat color than normal dark meat.The pig is easy to lead PSE meat, make color is pale.(5) microorganisms pollution meat stored at low temperature can make the meat surface color change.Contaminated bacteria, decomposing protein to make color dirty;Pollution of mold is formed in the surface of the meat such as white, red, green, black spots or fluoresce.