Abstract
The effect of the amount of ice added (20–60%) on the gel properties and water migration of Nemipterus virgatus surimi gel obtained with two-stage heat treatment was studied. The gel strength and water-holding capability (WHC) of the surimi gel with 30% ice added were significantly higher than those of other treatment groups (p < 0.05). The addition of 30% ice was conducive to the increase of protein β-sheet proportion during heat treatment, exposing more reactive sulfhydryl groups. These promoted the combination of protein-protein through disulfide bonds and hydrophobic-hydrophobic interactions, forming an ordered three-dimensional gel network structure. Meanwhile, the increase in hydrogen bonds promoted the protein-water interaction. Low-field nuclear magnetic resonance analysis showed that more bound water was locked in the gel system, reducing the migration of immobile water to free water and finally showing better gel properties. When the amount of ice added was insufficient (20%), the gel structure lacked the support of immobile water, resulting in deterioration of gel strength. However, excessive addition of ice (>30%) was not conducive to the combination of protein-protein and protein-water, forming a large and rough gel structure, resulting in the migration of immobile water to free water and ultimately exhibited weak gel properties.
Highlights
Surimi is an intermediate product of many seafood products, which is a refined and stable fish myofibril protein after multiple processes
It is speculated that the state and distribution of water molecules in the gel system play a key role in the improvement of surimi gel properties
This study explored the effect of different amounts of ice added (20–60%) on the gel properties of N. virgatus surimi gel under the same heat treatment conditions, and combined with water migration to clarify the effect of ice addition on the gel properties of surimi gel
Summary
Surimi is an intermediate product of many seafood products, which is a refined and stable fish myofibril protein after multiple processes. The myofibrillar protein of surimi unfolds, stretches, and aggregates during heating, forming a three-dimensional network structure and trapping water molecules, thereby increasing the gel properties of surimi products [1]. Low-field nuclear magnetic resonance (LF-NMR) is a powerful technique to characterize the state, distribution, and mobility of water molecules in biological macromolecule systems [5]. To clarify, the effect of the amount of ice added on the properties of surimi gel under the two-stage heat treatment has an important role in promoting the development of the surimi industry. The present study aims to confirm the influence of water migration on the gel properties of surimi, clarify the mechanism of the effect of ice addition on the gel properties of two-stage heat-treated surimi, and provide a reference for the processing of surimi products of other fish species
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