Depuration and starvation improves flesh quality of grass carp (Ctenopharyngodon idella)

Farmed grass carp (Ctenopharyngodon idella) at commercial size were transported to a natural lake for long-term depuration while being food deprived. The effect of depuration time on the quality of fish fillets was investigated based on proximate compositions, textural parameters and flavour characteristics. The results showed that protein and lipids, but not carbohydrates, were the major source of energy for grass carp during depuration and starvation. Textural parameters that included hardness, springiness, gumminess and cohesiveness increased significantly after depuration, as well as water-holding capacity of fish muscle. Taste and odour characteristics of grass carp muscle were obviously changed by depuration based on tests by an electronic tongue and nose. Off-flavour volatile compounds, such as nonanal and hexanal, were reduced after depuration. In conclusion, the quality of grass carp fillets was improved effectively by long-term depuration and food deprivation. More than 20days of depuration was appropriate for the enhancement of grass carp quality before marketing.