Tenderization of giant squid (Dosidicus gigas) meat pretreated with pulsed electric field and Asian seabass trypsin with the aid of vacuum impregnation

Abstract

Giant squid (Dosidicus gigas) meat (GSM) generally has a tough texture, significantly lowering its acceptability by consumers. To enhance tenderness, GSM was pretreated with pulsed electric field (PEF) at 250 V for 5 min (PEF-GSM). Thereafter, PEF-GSM was soaked in partially purified trypsin (PPT) from pyloric caeca of Asian seabass obtained from ammonium sulfate precipitation (40%–60% saturation). The soaking was done at various concentrations of PPT (0, 5, 10 and 20 units/mL) with the aid of vacuum impregnation (VI) (2 cycles). Subsequently, PPT-soaked GSM samples were incubated at 60 °C for 5 and 10 min, followed by cooking at 100 °C for 2 min. For quality assessment, untreated cooked GSM (CON-GSM) was also prepared. Lightness of PEF-GSM samples increased (p < 0.05), compared to that of CON-GSM. After hydrolysis with PPT, myofibrillar proteins were degraded with coincidental upsurge in AAGC (α-amino group content). Protein degradation and AAGC became more pronounced with increasing PPT concentration and incubation time. PEF-GSM treated with PPT at 20 units/mL (PEF-GSM-20) and incubated for 10 min had the decreased firmness and toughness values, however its cooking loss slightly increased. Degradation of myofibrillar proteins was reconfirmed by FTIR spectra and microstructure alteration. PEF-GSM-20 with incubation at 60 °C for 10 min showed higher overall likeness score (p < 0.05), indicating a significant improvement in acceptability of consumers. Thus, combined application of PEF, PPT (20 units/mL) and VI before incubation at 60 °C for 10 min significantly enhanced the eating quality of GSM, making it more preferable for consumers.