Effect of Different Packaging Methods on Protein Oxidation and Degradation of Grouper (Epinephelus coioides) During Refrigerated Storage.

Zhang Zhang,Xie Xie,Huang Huang

doi:10.3390/foods8080325

Abstract

This study investigates the effect of different packaging methods—namely, air packaging (AP), vacuum packaging (VP), and modified atmosphere packaging (MAP)—on the protein oxidation and degradation of grouper (Epinephelus coioides) fillets during refrigerated storage. The carbonyl group, myofibril fragmentation index, free amino acids, FTIR of myofibrillar proteins, and total protein SDS-PAGE were determined. The results showed that the protein oxidation degree of the fillets gradually increased as the storage time increased. The FTIR results indicated that the secondary structure transformed from an α-helix to an irregular curl. SDS-PAGE confirmed the degradation of the myosin heavy chain, and that myosin gradually occurred during refrigerated storage. Meanwhile, protein oxidation and degradation were highly correlated. Protein degradation was accelerated by protein oxidation in myofibrils, which included the increase of protein surface hydrophobicity and changes of the secondary structure. In fact, the protein oxidation and degradation of the grouper fillets were effectively inhibited by MAP and VP during refrigerated storage, and MAP (30% N2 and 70% CO2) had the best results.

Highlights

Grouper (Epinephelus coioides), which belongs to the order Perciformes and the family Serranidae, is a warm-water, offshore demersal fish that is referred to as “marine chicken” because of its considerable similarity in taste to chicken meat
The sulfhydryl content of the air packaging (AP) group decreased to 49.05 nmol/mg of protein on the sixth day, which was significantly different compared with the vacuum packaging (VP) and modified atmosphere packaging (MAP) groups
This study shows that the changes of carbonyl, sulfhydryl, and Ca2+ ATPase activity greatly varied with prolonged storage time, and demonstrates that the degree of grouper fillet protein oxidation was increased

Summary

Introduction

Grouper (Epinephelus coioides), which belongs to the order Perciformes and the family Serranidae, is a warm-water, offshore demersal fish that is referred to as “marine chicken” because of its considerable similarity in taste to chicken meat. With the development of artificial breeding and breeding technology, grouper has become an important economic fish along the coast of China [1]. Due to the quickening pace of life of the younger generation, fresh fish fillets are becoming the main marketing form of fish products [2,3]. Protein is one of the most important nutrients in aquatic products. The changing forms of protein mainly include protein oxidation and degradation. Carbonyl compounds formed by protein oxidation can change the cell structure of the myofibrillar protein, affecting the hydrophobicity index of fish protein [4,5]. The protein initially breaks down into many intermediates with the hydrolysis of endogenous

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