Determination Of Color And PH Threshold Of Dark Cutting Beef Based On Consumers' Visual Evaluation

When purchasing chilled beef,consumers often evaluate meat quality based on the color of the meat,but the main characteristics of dark cutting beef are dark,dry and firm surface,which directly affect consumers' purchase choices.At present,in most countries,it often uses pH to determine dark cutting beef,but the thresholds are different among different countries,and it is unclear of the relationshipbetween pH and consumers' acceptance.It is very important to establish the threshold off dark cutting beef based on consumers' visual evaluation,and it will helpmeat industry to classify beef reasonably.In addition,the successful application of Raman spectroscopy in the rapid determination and prediction of beef quality in recent years has also made it possible to quickly identify dark cutting beef.Therefore,in this study,ultimate pHs(pHu)of beef carcasses were monitored,and based on the consumers' visual evaluation of 90 beef images with different pHus,the color acceptance threshold of dark cutting beef was determined.Meanwhile based on the correlation analysis,the pHu threshold of dark cutting beef was determined.Finally,by the correlation analysis of Raman spectrum and meat color and pH value,the rapid determination of dark cutting beef wassucceed.The main findings are as follows:(1)The investigation showed that the pHu values of 766 cattle were mainly distributed between 5.40-5.59 and 6.40-7.99,and the proportion of pHu ? 6.20 accounted for 68%.According to the analysis of the beef cattle's pre-slaughter information,it found that the high incidence of high pHu beef was caused by long-time transportation,mixing lairage and violent operation on the beef cattle.(2)According to the survey of 4322 respondents,it found that the gender and age of interviewees had a significant impact on the color preferences of consumers,in which age had a positive correlation with the consumers' score;the surveyed regions had no effect on the results.Consumers' eating habits also had a significant impact on consumers' color preferences.Among them,consumers' preferences are positively correlated with consumer ratings,while beef consumption frequency is negatively correlated with consumer ratings.In addition,we also found that the importance of color,price,and flavor have a significant impact on consumers' purchasing willingness.The importance of color is positively related to consumer ratings,while the importance of price and flavor is negatively related to consumer sensory ratings.(3)Consumer's visual score was used as the standard for linear regression analysis with a rating of 4,and the acceptance thresholds of beef color characteristics are L* = 31.4,a* =16.4,b* = 6.5,C = 17.4,h = 22.5.As a* reflects the result of consumer visual evaluation most,it is used as the criterion for judging dark cutting beef in this study,and the corresponding pHu threshold is 6.20.(4)In this study,Raman spectrum scanning was performed on 166 normal beef samples and167 dark cutting beef samples,the Raman spectrum prediction models of normal beef and dark cutting beef were established based on support vector machine(SVM)algorithm.As a result,it was found that the accuracy of the model reached 0.90,indicates the rapid detection of dark cutting beef via this model was sucessful.In addition,it also found that the Raman spectrum wascorrelated with the beef color parameters,indicating that Raman spectrum can also predict beef color rapidly.