EFFECT OF REFRIGERATED STORAGE ON PROTEOLYTIC ACTIVITY AND PHYSICOCHEMICAL AND MICROSTRUCTURAL PROPERTIES OF GIANT SQUID (<i>DOSIDICUS GIGAS</i>) MANTLE MUSCLE

Abstract

ABSTRACT Giant squid ( Dosidicus gigas ) is abundant along the Pacific Coast of Mexico. It possesses a high proteolytic activity that makes it a low‐quality food material. Squid mantle endogenous proteases were partially characterized; physicochemical and structural changes during storage at 4C were also examined. High proteolytic activity was observed at acidic and alkaline pH values. Proteases were strongly inhibited by leupeptine and pepstatin A, as well as by phenyl methyl sulfonyl fluoride, indicating the possible presence of serine, cysteine and metal proteases. Myosin heavy chain was degraded during storage, as shown on sodium dodecyl sulfate–polyacrylamide gel electrophoresis patterns, resulting in a significant decrease ( P &lt; 0.001) in muscle water‐holding capacity, texture and gelling capacity. Muscle deterioration was evident in scanning electron micrographs, where the initial compact structure loosened during storage.