The effects of pre-slaughter resting periods on carcass and meat quality determined by digital image analysis

Inglés. In this study, the effects of different pre-slaughter resting periods on the carcass and meat quality of slaughtered beef cattle by Digital Image Analysis (DIA) and traditional methods (colorimeter) were determined. There were 4 resting periods, for those slaughtered without resting (RP0); 3 hours resting (RP3), 6 hours (RP6) and 12 hours (RP12) and formed as four different groups of animals and 375 samples in total from 10 animal carcasses from each group were collected. The measurements values of pH for the meat in each group, L*, a* and b* values and the RGB values obtained by the image analysis were subjected to ANOVA analysis by using GLM (General Linear Model) procedure and Tukey test was applied for pairwise mean comparisons. The samples of 2.5 cm thick Longissimus dorsi muscle area (LMA) between the 12th and 13th ribs were taken and pH measurements were obtained from the lumbar region. LMAs were measured using a planimeter and colour values with a colorimeter (L*, a* and b*) were determined. Digital images of the LMA samples taken from the carcass were subjected to image analysis. Both LMA and the colour distribution of red, green and blue (RGB) values and their density were determined by DIA. A-10 cm reference card was placed next to each object to eliminate the effects of shooting distance between the object and a digital camera. There were no statistically significant differences in LMAs of any group of animals obtained by of either method used in this study. All RGB colour values of the meat of the animals slaughtered without resting period (RP0) were significantly higher than those obtained in other resting periods. Similarly, L*, a* and b* values of the meat of the animals slaughtered without resting period (RP0) were significantly higher (P=0.01) than those in other resting periods. It was also found that there were no statistical differences in the colour values of the meats of the animals subjected to resting time 6 and 12 hours in both methods. Therefore, these results suggested that it would be appropriate for the animals to be rested for at least 6 hours before slaughter. It can also be concluded that DIA may open up new dimensions to determine some other meat quality parameters (texture, visual appearance, marbling, lean to fat ratio, lipid

protein oxidation levels etc.).