Gelatin hydrolyzed by papaya latex enzymes as an alternative cryoprotectant for frozen raw Pacific white shrimp (Penaeus vannamei)

Abstract

The cryoprotective activity of gelatin hydrolyzed by papaya latex enzymes at degrees of hydrolysis (DH) of 5%, 10%, 15%, and 20% were determined. The thermal hysteresis of gelati hydrolysate increased as DH increased up to 15% (2.31–4.19 °C) and decreased at DH of 20% (2.94 °C). The gelatin hydrolysate with 15%DH (G15), showing the highest thermal hysteresis, was subjected to fractionation and cryoprotective effect study in Pacific white shrimp. The fractionated peptide with the highest thermal hysteresis (5.19 °C) had a molecular weight of 1.7–4.2 kDa. After the soaking, G15-treated shrimp showed significantly lower and higher weight gain (7.33%) than those treated with mixed phosphates (16.12%) and distilled water (0.82%), respectively. Mixed phosphates- and G15-treated shrimp had lower α-glucosidase (AG) and β-N-acetyl-glucosaminidase (NAG) activities in exudate and lower thawing loss than distilled water-treated shrimp. G15-and mixed phosphates-treated shrimp also reduced freezable water content and maintained Ca2+-ATPase activity and protein solubility more effectively than distilled water-treated shrimp. Therefore, gelatin hydrolysate could be a potential alternative cryoprotectant in frozen raw shrimp.