Comparison of gilthead sea bream (Sparus aurata) and hake (Merluccius merluccius) muscle proteins during iced and frozen storage

Abstract

Gilthead sea bream (Sparus aurata) and hake (Merluccius merluccius) muscle behave differently during storage, whether in ice or deep frozen. Rapid changes have been observed in the texture of hake muscle during frozen storage, while gilthead sea bream has proved to be more stable. In order to ascertain the role of muscle proteins in the changes observed during storage, parameters related to protein functionality and the properties of extracted natural actomyosin (HAM) were studied initially and during storage in ice or at -20°C. Initially, the parameters related to functionality had higher values in hake muscle and extracted HAM than in gilthead sea bream. At the end of iced storage (22 days), less myosin heavy chain (MHC) and actin were extracted from hake, but there was practically no change in gilthead sea bream. This decrease was not accompanied by lower Ca2+-ATPase activity. Freezing produced no drastic changes, with lower values for gilthead sea bream. However, this species was more stable after 1 year, except for the Ca2+-ATPase activity of HAM. This suggests that the changes that hake proteins underwent during storage particularly affected properties related to aggregation, whereas in gilthead sea bream the changes hardly affected the formation of soluble or insoluble aggregates but did affect the active sites of myosin.