Investigation of objective evaluation method for meat firmness by computer image analysis of Holstein steers

摘要

The firmness of meat is deeply related to the quality and palatability of the meat, and has a large economic impact. However, it is difficult to perform a stable subjective evaluation of meat firmness because there is no objective standard model for judging. The purpose of this study was to investigate the objective evaluation method for meat firmness by using computer image analysis. Generally, the evaluation of the meat firmness is visually graded into 5 scores (1 : poor-5 : fairly good). In this study, the meat firmness was minutely evaluated into 15 scores by the expert grader of the meat quality evaluation for 51 Holstein steers. The digital images of the carcass cross section were taken between the 6th and 7th ribs by the mirror-type photographing equipment, and the macro images of M. trapezius at the 6th and 7th ribs were taken with the digital camera attached with an ultra macroscopic lens. Using the digital images of carcass cross section, the ratio of marbling area to rib eye area (FATPER) as well as traits for marbling particles were obtained by image analysis. Also, in this study, the boundary division between muscle bundles on the zoom image of M. trapezius, was determined as a muscle bundle gap. The ratio of gap of the muscle bundlesoccupied in the object region of 3008 X 2000 pixels (GAPPER) and traits for the gap of the muscle bundles were also calculated for the macro images of M. trapezius. The correlation coefficient between detailed evaluation score of the meat firmness and FATPER was highly significant (r = 0.73, P < 0.01). On the other hand, the correlation coefficient between GAPPER and the detailed evaluation score for the meat firmness was —0.75 {P < 0.01). Multiple regression analysis was conducted in order to evaluate the firmness of the meat by objective image analysis variables. Selected variables of the multiple regression equation were GAPPER with the negative regression and FATPER with the positive regression ( R~2 = 0.71, P< 0.01). Results of this study showedthat the meat firmness was highly related to the condition of the muscle bundles and the possibility of the objective evaluation by means of image analysis for the meat firmness.