| Color stability is one of the important characteristics of meat and meat products. It is the primary quality attribute seen by the consumer, who may use it as an indication of freshness and wholesomeness. As the way of future development of meat, chilled meat was introduced China lately and a lot of quality defects still exist currently. Discoloration is one of the important problems which will shorten chilled meat’s shelf life. Many factors affecting color stability, such as myoglobin oxidation, metmyoglobin reducing activity, lipid oxidation and mitochondrial oxygen consumption. Deep research had reported on single factor affecting color stability in overseas, but changes and relationship of predominant bio-factors correlating discoloration during storage has little reported. Lactate enhancement can significantly inhibit the growth of microorganism, but its impact on meat color is still in dispute, and little report has been found in domestic. The purpose of this study is to reveal the mechanism of beef discoloration during chilled storage, and to provide a theory basis for seeking a scientific method effectively to inhibit discoloration. Based on the purpose, the research was designed by comparing apparent fading theory about three bovine muscles and oxidation characteristics of endogenous bio-factors, meanwhile extracting myoglobin from bovine heart and determining oxidation stability of myoglobin under different physical and chemical factors in viro.1. Analysis of major bio-factors affecting beef color stabilityThe experiment was designed to investigate the major bio-factors affecting color stability from different bovine muscles. Three representative bovine muscles-M. longissimus lumborum (LL), M. semimembranosus (SM), and M. psoas major (PM) were obtained from8beef carcasses. Instrumental color(L*, a*, b*, Chroma, Hue angle), pigment content, pH value, MDA content, NADH concentration, LDH and metmyoglobin reductase activity were measured every two days in pallet package over the period of7d retail display at0-4℃. The order of color stability of the three muscles was:LL>SM>PM. The a*value, NADH concentration, LDH and metmyoglobin reductase activity was the highest in LL and the MDA content was the least. While the a*value, NADH concentration, LDH and metmyoglobin reductase activity of PM was the lowest and MDA content was the highest. NADH concentration, LDH and metmyoglobin reductase activity in beef muscle correlate with color stability significantly (P<0.05)2. Isolation, characterization and redox stability of oxymyoglobin from bovine heartThis study aimed to characterize the oxymyoglobin stability under different physical and chemical factors from bovine heart. Myoglobin was isolated and purified by ammonium sulphate precipitation (75-100%saturation), followed by Sephadex G-75chromatography. Its purity was identified by scanning spectrophotometry. The pH and thermal stability of myoglobin were tested under a pH range of3.0-11.0and a temperature range of20-60℃, respectively. In addition, oxymyoglobin was incubated with HNE and lactate, the redox stability of oxymyoglobin was expressed by metmyoglobin percentage. The result showed:the stability of oxymyoglobin was decreased and the formation of metmyoglobin increased with the increasing of temperature. The stability of metmyoglobin in pH7.0was the highest, and the characteristic absorption peak of myoglobin disappeared. As compared with the control group, HNE improved the accumulation of metmyoglobin, while lactate decreased the accumulation of metmyoglobin. Oxymyoglobin redox stability in neutral and alkaline environment was significantly higher than acid environment (P<0.01). HNE can improve the autoxidation of oxymoglobin, while lactate inhibit the autoxidation of oxymoglobin.3. Effects of calcium lactate on color stability of beef pattiesIn order to investigate the effects of addition of calcium lactate on color stability of chilled beef patties, color stability, pigment content, lipid oxidation and myoglobin reductase activity were measured after they were enhanced with calcium lactate at concentrations of0.1%,0.3%and0.5%in the finished product during refrigerated storage at (4±1)℃, respectively. The results indicated that:addition of calcium lactate to meat patties inhibited myoglobin oxidation, lipid oxidation and increased myoglobin reductase activity and color stability, however the L*value decreased significantly (P<0.05) during refrigerated storage. Calcium lactate (0.3%) significantly inhibited lipid oxidation and increased color stability of beef patties during chilled storage. |
PDF Full Text Request