| Bison has excellent nutrition and eating quality traits, but have less color stability compared with beef. The purpose of this study is to explore the high voltage stimulation after slaughter and nitrite film packaging on improving bison quality and color of retail meat.40 Canada bisons were slaughtered, split and divided into high voltage stimulation groups side and control side, then cut into subsamples and stored according to different ageing time. Their fat and protein, myoglobin, pigment and other basic bison carcass traits were measured, and the change of their color, tenderness and intramuscular glycolysis metabolism and related changes were observed, sensory assessments to the steaks and burger of ageing 13 days were made by the panelist. Steaks and burgers in NIT vacuum package from different ageing time comparing with in PVC package and normal vacuum package, were observed of the change to their color, tenderness, and the fatty acids, then the effect of packaging on microbiology growth on the bison meat in it wre observed. The results showed that:1.In this project, Bison was classified into 47.5% categories of A1, 35% to A2, 12.5% to A3, 2.5% to A4 and 2.5% to B1. It shows that the high quality meat ratio of the high quality beef cattle raised in the pasture has a good prospect of market development. The percentage of 1 carcass yield of Bison was higher than that of beef cattle. The color of the Bisonwas darker than that of beef, and the concentration of the pigment was 10.02 mg/g, and the content of the pigment was higher than that of beef cattle. The marble is also small, the total ratio of fat is very low, but the total fat percentage of unsaturated fatty acids is higher than the corresponding proportion of beef cattle, unsaturated fatty acid ratio is 56.56%, unsaturated fatty acids of which is 47.24, polyunsaturated fatty acids is 9.32%.2. High voltage stimulation had a limited effect on bison quality characteristics, there was not a significant decline in pH(P = 0.11) after stimulation postmortem, the color of the meat and shear force were no significant improved versus the contrast samples(P > 0.05), the muscle glycogen remain in bison(> 70(including mol. G- 1) and total sugar metabolism related potential(-94μ mol/g) were still at high level, which shows that bison should have enough energy for high voltage stimulation.For most taste sensory properties after cooking, steak and burgers in the high voltage stimulation group and the control group was not significantly different. However, steaks in high voltage stimulus group had slightly higher score in last juiciness sensory than that of control group(P < 0.05), burgers in high voltage stimulation group had significantly lower score in starting juiciness and juiciness of sensory than control group(P < 0.05). High voltage stimulation and ageing time had significant interaction on MFI(P = 0.03), bison meat in high voltage stimulus group of ageing time 6 d and 13 d is significantly higher on MFI than the control group. bison meat in High voltage stimulus have significantly lower drip loss than the control group(P< 0.05), drip loss of the steaks in high voltage electrical stimulation group was lower than that in the control group(P <0.05), the result from above indicated that high voltage electrical stimulation had significant effects on the decomposition rate of protein as ageing time increased,and had better water holding capacity. Tenderness of bison steak was improved, the shear force decreased as the ageing time increased after slaughter(p<0.0001).3. the beef tenderness has been improved with the increase of the ageing time after the slaughter of bison, and the shear of the was reduced(p<0.0001). With the increase of ageing, the value of L* was also observed to be significantly increased(p<0.0001), the value of Chroma(p<0.001) and value Hue(p<0.01) was also significant, but the consistency of the time was maintained. In the mature stage of 13 d, the subjective color score was the highest, which was significantly higher than that of 6d and 20d(p=0.004) in the mature stage.4. The nitrite(NIT) embedded film had significant effect on color stability of bison meat. Subjective observe bison steaks in NIT package from different ageing time, the color of the meat changed from " moderately dark red" to " slightly dark red"(P < 0.05) which meant NIT packag improved the bison meat color stablitys. Bison meat was measured by instrument, Hue value declined significantly from the first day when the sample was packaged and place on the retail case to 2nd day(P < 0.0001), meant red color increased in 2 days; From 2nd day to 4th day, hue value almost remain unchanged. NIT packaging for meat had no significantly effect on th e shear force(p = 0.7). The average of bison pigments concentration was 10.02 mg/g, unsaturated fatty acid ratio was 56.56% including monounsaturated fatty acids(47.24%) and polyunsaturated fatty acids(9.32%), these compositional traits affect the color stability of bison meat. The bison burgers subjective observation and instrument observations indicated that NITpackage had good effects on color stability of bison burgers, just like steaks Thiobarbituric acid reactive substances(TBARS) test of bison burger showed there were no significant change in NIT packaging group from 0 d to 4 d retail, but that were significantly higher in the control group(P < 0.05), which showed NIT package can inhibited fat oxidation in NIT package.5. NIT package inhibited growth of bacteria in the surface of the meat better than the commonly used PVC packaging. It were about 100 times less in NIT package for e. coli(P<0.0001), 0.5log for lactic acid bacteria(P=0.0058) and 1.5log for the psychrophilic bacteria(P = 0.0001). NIT package had stronger inhibition effect for e.coli and psychrophilic bacteria than lactobacillus. There were significantly higher(p=0.04) on antibacterial activity on lactic acid bacteria from Meat surface side contacted with nitrite embedded film versus other side contacted with dri-loc. |
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