The relationship between colour and pH in cold - stored quail breast muscle

The purpose of this study was to analyse the colour of the breast muscles of Japanese pharaoh quail on the first day after slaughter and again after further six days of cold storage, in relation to their muscle ph. The material for the study consisted of 40 breast muscles taken from the carcasses of six-week-old Japanese Pharaoh quail. Based on pH results, the muscles were divided into three groups: I (pH = 5.51-5.70), II (pH = 5.71-5.90) and III (pH = 5.91-6.10). After this the muscles were stored for a further 6 days at 4°C. It was found that the pH of freshly dissected quail breast muscle is a good indicator of the colour stability of muscles cold-stored at 4°C for six days. The lowest degree of colour stability was observed in the pH range 5.51-5.70. In the sensory evalua- tion muscles displaying this degree of colour instability were considered unacceptable or barely acceptable. In contrast, muscles in the pH ranges 5.71-5.90 and 5.91-6.10 displayed a high degree of colour stability and were considered acceptable in the sensory evaluation. The colour changes that occurred during storage of the muscles were due to changes in the values of all of the colour parameters (L*, a*, b*, C* and ho); however, the greatest changes were found in the case of redness (a*) and the hue angle (ho). The changes were caused both by alterations in the amount of pigment reached by light, and by changes in the relative amounts of the chemical forms of myoglobin.