Investigation And Analysis On Beef Color Of Different Ultimate PH Values

With the continuous development of economy,people's living standard has been gradually improved,beef consumption has increased year by year,beef has good nutritional value,by the consumer favorite.Color is one of the important indexes of beef quality,it is also an important factor in determining whether the consumer buy.So it is very important to keep the fresh red and color stability of beef.In the actual production process,due to the reasons of beef cattle,feeding slaughtering process of transportation,and postmortem mature caused unnormal beef color,and the phenomenon of black color appears to generate DFD beef.In addition to the dark color,dark cutting beef has many disadvantages,such as high pH value,high intracellular water,low oxygen partial pressure,susceptible to microbial infection,resulting in bad taste and so on.But the DFD beef has good tenderness.DFD meat production has connect with postmortem ultimate pH value.The main factors about the impact of beef color were pH,concentration of myoglobin,metmyoglobin reduction ability and NADH content.Beef initial color(postmortem within 24 hours)of meat color formation process,and it is the postmortem metabolism of the most productive stage,mitochondrial OCR is the highest,NADH content and enzyme activity is the highest.Therefore,it is critical stage of flesh chemical index and the color correlation.In this experiment,by measuring the different limits of pH value of the color properties of beef basic index,and oxymyoglobin,the relative content of deoxymyoglobin,metmyoglobin,NADH levels,metmyoglobin reducing ability index,analyse difference of beef clolor in different ultimate pH values.Select 90 Luxi and Simmental crossbred cattles with similar age and weight.Afterslaughter measure temperature,pH value and meat color of basic index at 45 min,3h,6h,12 h and 24 h,and beef cattles were divided into three groups according to the ultimate pH value,divide samples in 3 group: low pH value group(5.40<pH<5.80)intermediate pH value group(5.80<pH<6.10)and high pH value group(pH>6.10),each group ttook six bulls and points ttook samples at corresponding time,quickly into the liquid nitrogen cooling,to prepare for the next step for determination of color related indicators.The results show:There was no significant difference in the body temperature of pH group at different limit.Indicating that the limit pH value has no effect on the carcass temperature.Low pH value of beef muscle has a significant downward trend.The pH value in high pH value group at 12 h after slaughter basically unchanged.After slaughter,the changes of pH value were affected by the glucolysis.Low pH value group's basic color index was significantly better and high pH value group with increasing time after slaughter,basic meat color index increased to the best at 24 h after slaughter.The content ratios of metmyoglobin and oxymyoglobin increased with the increase of time,metmyoglobin content ratio in low ultimate pH value group was lower than high ultimate pH value group,and oxymyoglobin content ratio in low ultimate pH value group was higher than that in high ultimate pH value group.Deoxymyoglobin relative content decreased gradually with the increase of time,and the high pH value group relative content higher than two treatment groups.MRA in different ultimate pH value groups gradually increased with the increase of time,low pH group of metmyoglobin reduction ability is higher than the intermediate pH value group and high pH group.At 24 h,MRA of low pH value group had different differ with two other treatment groups.MRA showed a downward trend with the increase of pH value.