Effects of Freeze-Thaw Cycles on Gel-Forming Ability and Protein Denaturation in Alaska Pollock Frozen Surimi

Shuji Abe,Kazuhito Kajiwara,Takuma Asada

doi:10.1155/2019/3760368

Abstract

Frozen surimi may be damaged by freeze-thaw cycles (refreezing) under various conditions. However, few studies have examined the deterioration of the quality of refrozen surimi. The objective of this study was to determine the deterioration mechanism of refrozen surimi. We used Alaska pollock frozen surimi, which has been studied extensively for gel formation. Refreezing decreased the breaking strength and breaking strain of the heated gel. The length of the line in the diagram between breaking strength and gel stiffness (L value, which indicates the level of change in the breaking strength and gel stiffness with setting time) was also decreased. In contrast, the effect of refreezing on the texture of the gel without the setting process was small. The polymerization rate of myosin heavy chain in refrozen surimi during the setting process was slower than that in nonrefrozen surimi. Additionally, the Ca-ATPase activity of surimi was reduced by approximately 30% with each refreezing. These results demonstrate that the reduction in gel-forming ability by refreezing was caused by the decreased polymerization rate of myosin heavy chain because of myosin head denaturation. We also found that quality deterioration including myofibrillar protein denaturation of frozen surimi occurred mostly during first refreezing rather than during second refreezing. Overall, refreezing and/or repeated refreezing of surimi simply decreased the suwari gel-forming ability without changing the characteristics of surimi. The primary cause of the decrease in gel-forming ability induced by refreezing is considered to be the suppression of myosin heavy-chain polymerization during setting.

Highlights

It is well known that refreezing reduces the quality of food products [1, 2]
Abe et al [6] found a linear relationship between breaking strength and gel sti ness
Erefore, the length of the line in the relationship diagram of breaking strength versus gel stiffness indicates the level of change in the breaking strength and gel stiffness with setting time. us, we considered that the length would be an indicator of suwari gel-forming ability

Summary

Introduction

It is well known that refreezing reduces the quality of food products [1, 2]. Refreezing causes damage such as cell destruction, protein denaturation, and surface drying in foods. E most important property of frozen surimi is its gel-forming ability, which depends on the structure of myo brillar proteins in surimi. Denatured myo brillar protein in surimi cannot form gel [4]. In Japan, the punch test has been used to evaluate the gel-forming ability of frozen surimi. Abe et al [6] found a linear relationship between breaking strength and gel sti ness. They revealed that the line position, linear slope, and plot dispersion depend on the property of frozen surimi. E relationship diagram of breaking strength versus gel sti ness revealed the following. The plots of suwari gel with microbial transglutaminase tended to be scattered. (3) When the plots formed clumps, the surimi did Journal of Food Quality

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Conclusion