D. Varga, Cs. Hancz, A. Szabó, T. Molnár. Results and discussion EFFECT OF SLAUGHTERING METHOD ON THE MEAT QUALITY AND RIGOR DEVELOPMENT OF COMMON CARP (Cyprinus carpio) D. Varga, Cs. Hancz, A. Szabó, T. Molnár. Kaposvár University, Faculty of Animal Science, H-7400, Kaposvár, Guba S. str. 40. Hungary Introduction Many circumstances can modify the value and meat quality of fishes: feeding regime, water quality and stress. Perimortal stress induced biochemical processes change blood and tissue characteristics, e.g. increase the lactate and the glucose level. These changes have an impact on the post mortem processes and modify the quality of the product. Effects of slaughtering method on the meat quality were investigated in many cases on lots of seawater and freshwater fish species but common carp in this context has not yet been tested. Table 1. Mean quality parameters of the carps slaughtered by different methods Materials and Methods 45 common carps were introduced into plastic fish tanks and kept 4 weeks long. Fishes were divided in three groups and slaughtered by different methods: percussive stunning (blow on head), live chilling (in ice slurry) and CO2 asphyxiation (in CO2 saturated water). Every fish were gutted and 10 fish by group were subsequently filleted. Fillet pH and color (CIE Lab) was measured at 24 h post mortem. Water holding capacity of the fillet was determined by dripping, cooking and thawing loss. The remaining 5 gutted fish of each group were used for recording rigor progression. Fishes were stored on solid flat surface. Measurements were performed by placing the carp so that the body part behind the posterior end of the dorsal fin was hanging over the edge, unsupported. The rigor angle was calculated as α=tan−1 (X/Y), where X: length (cm) of the horizontal leg of the right-angled triangle, and Y: length (cm) of the vertical leg of the right-angled triangle. Results and discussion Slaughtering methods had not significant impact on the meat quality of common carp, and no significant differences were found between groups due to the low number of data. CO2 asphyxiated group had highest pH value and highest values of redness (a) and yellowness (b). In each groups, stiffening started about 6 h after slaughtering. Course of rigor development is similar in the case of the live chilled and the percussive stunned groups. Subsequently, rigor process of the CO2 asphyxiated fish is slower, the muscle stiffening is not so hard than other groups. In conclusion, CO2 asphyxiation slightly influences the pH, flesh color and rigor development of common carp. References Olsen, S.H., Sorensen, N.K., Larsen R., Elvevoll, E.O., Nielsen, H. (2008): Impact of preslaughter stress on residual blood in fillet portions of farmed Atlantic cod (Gadus morhua) Measured chemically and by Visible and Near-infrared spectroscopy, Aquaculture 284: 90–97. Olsen, S.H., Sorensen, N.K., Stormo S.K., Elvevoll, E.O. (2006): Effect of slaughter methods on blood spotting and residual blood in fillets of Atlantic salmon (Salmo salar), Aquaculture 258: 462–469. Wilkinson, R.J., Paton, N., Porter, M.R.J. (2008): The effects of pre-harvest stress and harvest method on the stress response, rigoronset, muscle pH and drip loss in barramundi (Lates calcarifer), Aquaculture 282: 26–32. Figure 1. Rigor developement of gutted carps during 48 h storage Acknowledgement The support of the Hungarian Scientific Research Fund (OTKA 83150), the Bolyai János research grant by the Hungarian Academy of Sciences (BO_26/11/4) and the TÁMOP 422b project is gratefully acknowledged.