Fishy odorants in pre-processed fish fillet and surimi products made from freshwater fish: Formation mechanism and control methods

In recent years, freshwater fish as a raw material for pre-processed fish products have caught great attention. However, freshwater fish are generally considered to have a heavier fishy and earthy smell than marine fish, thus restricting their further development and consumer acceptance. This suggests that the fishy odor should be effectively controlled to enhance the application of freshwater fish in pre-processed fish products as well as improve consumer acceptability. The present review focuses on the main fishy odorants, their formation mechanism, and control methods for pre-processed freshwater fish products (fish fillet and surimi products). Additionally, the potential challenges in fully understanding the formation of fishy odorants and effective fishy odor control in pre-processed freshwater fish products are also discussed. The compounds associated with off-flavors are mainly generated by microbial action, protein degradation, and lipid oxidation. Fishy smell reduction for pre-processed fish fillets and surimi products can be largely achieved by decreasing flavor precursors in raw materials (purifying or rinsing treatment) and adopting appropriate processing methods (adding exogenous substances, thermal and non-thermal, and using food package). Additionally, more attention should be paid to the influence of the concentration and threshold of odor substances on the odor properties of freshwater fish and their products, and the effects of in vivo aroma releases in aquatic-based food systems. This review will facilitate the understanding of controlling fishy odor in freshwater fish products and promote the development of the related industry.