Impact of far-infrared radiation-assisted heat pump drying on chemical compositions and physical properties of squid (Illex illecebrosus) fillets

Squid fillets were dried in a heat pump (HP) dryer alone or combining with far-infrared radiation (FIR) with the power of 500, 1,000, and 2,000 W at 50 A degrees C and air flow rate of 0.8 m s(-1). Proximate composition, total volatile basic nitrogen (TVBN), fatty acid composition, trimethylamine-N-oxide demethylase (TMAOase), dimethylamine (DMA), trimethylamine (TMA), color, and microbial changes of squid were recorded. Results showed that FIR in combination with HP decreased TMAOase, TMA, TVBN, polyunsaturated fatty acids (PUFA), and total aerobic bacterial counts, but increased both saturated (SFA) and monounsaturated (MUFA) fatty acid content, compared with HP alone. Dried squids had higher values of redness and yellowness, but lower values of lightness (L) than raw ones. No significant differences were found in protein, DMA, or L values among all dried samples. The inhibitory effects of FIR on TMAOase, TMA production, and microbial growth were more obvious with increase in the power supplied to the FIR rods. The present data suggest that FIR in combination with HP technology has the potential to retard the quality deterioration of squid.