Improving the freeze-thaw stability of fish myofibrils and myofibrillar protein gels: Current methods and future perspectives

Freeze-thaw (F-T) stability of frozen foods has been a hot topic and focus in recent years. The F-T cycles caused by the fluctuations of temperature during storage and transportation have detrimental effects on the properties of fish myofibrils and myofibrillar protein (MP) gels. This review provides an outline of recent research progress to improve the F-T stability of fish myofibrils and MP gels, as well as the insight into the in-depth mechanism. There are five main strategies to improve the F-T stability of fish MP gels, which are direct heating to prepare fish gels, fast freezing technology, addition of protein hydrolysate or antifreeze protein, incorporation of polysaccharides, and addition of quinoa protein Pickering emulsion (QPE) into fish protein gels. Direct heating could decrease the ice crystal size compared with two-step heating process. Fast freezing technology deceases the ice crystal size and the free water content after thawing. The antioxidant activity of protein hydrolysate and polysaccharides weakens the oxidation of sulfhydryl groups, prevents the protein solubility from decreasing and maintains the secondary structure of proteins. QPE addition accelerates the freezing rate, which reduces ice crystal size, prevents water migration and maintains protein structure of fish MP gels. However, innovative and cost-effective methods are still needed from the perspective of industry. It is proposed that emerging freezing and thawing technology and incorporation of ice structuring protein should be effective to resist the F-T damage. The information presented in this review will be useful for future studies.