Effect of different drying methods on the myosin structure, amino acid composition, protein digestibility and volatile profile of squid fillets

The impacts of freeze drying (FD), hot-air drying (AD), and heat pump drying (HPD) on myosin structure, amino acid composition, protein digestibility and volatile compounds of squid (Todarodes pacificus) fillets were evaluated. Freeze-dried squids showed similar amino acid composition to that of raw squids, but differed from that of AD and HPD samples. The percentage of in vitro digestibility followed the order of FD (76.81%) > HPD (70.51%) > raw (67.99%) > AD (61.47%) samples. AD caused more damage to squid myosin structure than HPD, while FD effectively retained the myosin integrity. Drying decreased total number of volatile compounds, but increased the content of total volatile compounds based on GC × GC-TOFMS results. HPD and AD samples had the highest and lowest total numbers and contents of volatiles, respectively. In general, FD provided squids with the best quality, followed by HPD. Considering the production cost and product quality, HPD demonstrated the potential for industrial application.