Effects of Kudoa thyrsites on Proximate Composition and Texture of Merluccius capensis and Zues capensis.

Abstract

Kudoa thyrsites is a myxosporean endoparasite that infects fish, frequently resulting in myoliquefaction, impacting the texture and eating quality of fish muscle. The aim of this study was to investigate the effects of K. thyrsites infection on the proximate composition and texture parameters of raw fillets from two South African economically important species: Cape hake (Merluccius capensis) and Cape dory (Zues capensis). Infection status was determined using real-time quantitative polymerase chain reaction. Association of Official Agricultural Chemists (AOAC) methods were used to determine moisture, protein, fat and ash of raw fillets. Texture Profile Analysis measured springiness and gumminess, using an Instron. The study revealed host species-specific impacts. For Cape hake, K. thyrsites infection showed no statistically significant effect on proximate composition or texture (springiness, gumminess). In contrast, Cape dory demonstrated a significant increase in moisture content in infected (76.48%) compared to uninfected samples (75.22%). Furthermore, infected Cape dory exhibited significantly lower springiness (5.98%) compared to uninfected samples (6.30%), correlating with a softer texture. These findings are the first for Cape dory and of interest to the fishing industry for developing quality assessment tools.