Chemical and functional properties of sardine (Sardina pilchardus W.) dark and light muscle proteins during frozen storage. Effect of washing on mince quality / Propiedades químicas y funcionales de las proteínas del músculo oscuro y claro de sardina (Sardina pilchardus w.) durante el almacenamiento en congelación. Efecto del lavado en la calidad del músculo picado

Abstract

This paper examines the effects of eight months of frozen storage on the protein conformation and functionality of whole, light and dark sardine muscles, and washed mince. The variation in protein surface hydrophobicity and Ca-ATPase activity was different in dark muscle from that in whole muscle over the storage period. The dark muscle lacked gel forming capacity because of its higher fat content and a greater presence of low molecular weight proteins, and it also became insoluble faster than the light muscle. The Ca-ATPase activity of the actomyosin extracted from the dark muscle was higher than in light or whole muscle during the first three months. Washing the minced muscle induced conformational changes in the myosin molecule which, together with the added cryoprotectants, contributed to greater functional stability of the washed mince at least during the first three month's storage, at which stage gels were somewhat softer and more elastic than with unwashed mince.