The change characteristics in moisture distribution, physical properties and protein denaturation of slightly salted silver carp (Hypophthalmichthys molitrix) fillets during cold/hot air drying processing

The effects of cold air drying (CD) and hot air drying (HD) on the physical properties and protein stability of slightly salted silver carp fillets were investigated in terms of water-related indicators, texture profile, color and protein denaturation analysis. The results indicated moisture content of fillets exponentially decreased to 1.19 and 1.07 g water/g drying matter at the end of drying, respectively, accompanied with the decreases in water activity, and water mobility based on the results of leftward shifted T-21 and T-22 relaxation time. The gradual increase of hardness and chewiness, and decrease of adhesiveness of dried fillets were observed in both groups during the drying process. By contrast, CD made fillets with higher hardness and chewiness properties when compared to HD under similar moisture content. The more intense browning reaction was observed in hot air dried fillets, reflecting by the sharp increase of b* value (p < 0.05) from the initial 1.25 to final 13.44. Besides, the results of protein-related indicators showed HD easily resulted in protein aggregation and secondary structure degradation. Summarily, this study revealed the change characteristics of salted silver carp fillets during two conventional air dryings, providing a basis to further propose reasonable combination drying programs.

Automated summary

The effects of cold air drying and hot air drying on slightly salted silver carp fillets were different, with cold air drying resulting in fillets with higher hardness and chewiness properties while hot air drying easily led to protein aggregation and structure degradation.