High pressure effects on heat-induced gelation of threadfin bream (Nemipterus spp.) surimi

• The initial treatment of HPP triggered the degradation and produced weak gels.
• The balance between TGase and proteinase(s) determined the gel microstructure.
• The degradation retarded the formation of disulfide bonds.

We sought to determine, in threadfin bream surimi system, if 40 °C incubation carried out simultaneous with, or following, HPP might also induce a more effective setting on subsequently cooked gels. Threadfin bream surimi pastes were subjected to HPP 200 or 300; at 5 °C (little or no setting effect expected during HPP at this temperature) for 15 min or at 40 °C (optimal setting temperature for threadfin bream pastes) for 15 or 30 min. Pastes were then directly cooked (90 °C for 20 min) (pressureP°C/time > C), or first allowed to undergo setting at atmospheric pressure (40 °C for 60 min), followed by cooking (90 °C 20 min) (pressureP°C/time > Stime > C). With or without followed setting treatment at 40 °C, HPP treatment at 40 °C, or even lower pressure at 5 °C for shorter time (200MPaP5°C/15min > S40°C/60min > C) produce weak cooking gels. Two opposite actions of cross-linked polymer (CP) and degraded protein (DP) was observed during the HPP treatment. The given HPP treatment was sure to triggered the detriment of protein in combined treatments, the followed setting treatment after HPP enhanced the degradation of protein as well. The formation of disulfide bonds during HPP and cooking treatments was retarded, which was attributed to the influence of protein degradation behavior. Scanning electron microscopy revealed, with giving a prior HPP treatment, the fiberlike structure gradually disappeared and the compact microstructure increased in final cooking gel.