Protein structural transitions and cryo-stability of shrimp gel: Effects of setting time at 30 °C in a novel processing system

Abstract

This study investigated the effects of setting time (0–90 min) at 30 °C on the quality of frozen shrimp gels using Litopenaeus vannamei as the raw material within a novel “setting-freezing-cooking" processing system. The results revealed that with increasing setting time, hydrogen bonds, hydrophobic interactions, α-helix, and β-sheet initially increased and then decreased, which in turn influenced the gel's properties. After 15 min of setting, shrimp proteins were fully unfolded, with hydrogen bonds and hydrophobic interactions contributing to the maintenance of conformational stability in the shrimp gels. This resulted in an increase in α-helix and β-sheet, which in turn enhanced the textural properties of the gels, elevated the content of immobilized water and bound water, and optimized the viscoelastic properties to their peak state. During frozen storage, ice crystal formation damaged the protein structure of the shrimp gels, leading to reduced dynamic viscoelasticity, loosening of the gel network, and an increase in random coil structures - changes that consequently enhanced drip loss. However, shrimp gels that were set for 15 min exhibited enhanced resistance to ice crystal damage during frozen storage. This finding indicated that a 15-min setting time more effectively inhibited gel deterioration during frozen storage. It is anticipated to provide a theoretical basis and practical guidance for optimizing shrimp gel production and quality control.