Emerging muscle abnormalities in broilers: impact on quality traits of raw meat for further processing

Introduction. In the past few decades, the breeding companies focused on the genetic selection of high growth-rate and breast yield chicken hybrids. Within this context, although an overall improvement in the live performances was achieved, an increased incidence of several emerging muscle abnormalities termed as White-striping (WS) and “Spaghetti-Meat” (SM) was observed. Materials and Methods. Ninety-six boneless and skinless Pectoralis major muscles were selected from the same flock of high-breast yield hybrids (males) in the deboning area of a commercial processing plant and classified by two experienced people according to the presence of WS and SM defects: 24 Normal (NORM), 24 WS, 24 SM and 24 WS/SM samples. Implications of WS and/or SM abnormalities on quality characteristics (morphometric measurements, pH, colour, physicochemical state of water molecules by LR-NMR) and muscle proteins traits (as assessed by SDS-PAGE analysis, Myofibrillar Fragmentation Index, protein solubility and oxidation) were assessed. In addition, since both WS and SM defects seemed to mainly affect the superficial part of the Pectoralis major muscle, each parameter was separately determined in the superficial and in the deep part of each fillet in order to assess whether any difference might be attributed to the sampling position. Results. The findings of the present study evidenced that WS and SM abnormality occurring alone or combined within the same Pectoralis major muscle significantly affected all the parameters assessed within this study. In detail, although only negligible effects might be observed within the deep part of the fillet, the occurrence of WS and SM defects severely affected the superficial layer of the P. major muscle. Furthermore, even if no relevant differences were found concerning colour, all samples affected by muscle abnormalities exhibited significantly higher pH and a remarkable increased proportion and mobility of extra-myofibrillar water fraction. In addition, although no significant differences were found concerning both myofibrillar and sarcoplasmic proteins solubility, protein functionality was found to be significantly impaired within the samples affected by WS and/or SM muscle abnormalities. This might be partly explained by the higher fragmentation index, the increased carbonylation level as well as by the overall altered myofibrillar and sarcoplasmic protein profiles observed within the abnormal samples. Conclusions. This study evidenced that especially SM abnormality can impair breast meat quality properties as previously evidenced for wooden-breast condition. Within this context, considering that abnormal fillets are normally downgraded by the poultry industry and included as raw materials for processed products manufacture, further studies are needed in order to identify the proper technologies and formulations to apply. Additional information would also help to identify the proper proportion of abnormal meat to be included within the formulation of processed products without impairing quality traits and functionality