46G-11 |
Changes in protein solubility during frozen storage of giant squid (Dosidicus gigas) |
O. DUBLAN-GARCÍA1, G. Hernández-Ramírez, I. Guerrero-Legarreta, and E. Ponce-Alquicira. (1) Biotecnología, Universidad Autónoma Metropolitana, Av. san Rafael Atlixco No.186, Col. Vicentina. Apartado postal 55-535, México, D.F., 09340, Mexico Giant squid is one of the main aquatic resources in the Pacific coast of Mexico. It is usually frozen in blocks; however, it posses a shorter shelf life as compared to other marine species, reducing the possibilities for commercialization. Poor freezing practices may induce deterioration of frozen fish products promoting changes in texture and the development of undesirable flavors. Few reports were found in the literature regarding quality lost of frozen squid. The aim of this work was to investigate changes in protein solubility during frozen storage of giant squid (Dosidicus gigas) mantle muscle. Portions of squid mantle were packed in polyethylene films and stored in a commercial freezer at –10, –18 or –70°C during 24 weeks. Samples were analyzed every 4 weeks for water holding capacity (WHC), pH, protein solubility, total volatile nitrogen (TVN), and formaldehyde (FA). Variations in pH and WHC were observed; pH increase was associated to an increment in TVN, being more evident in samples stored at –10°C, with concentrations around 30 mgN/100g after 16 weeks of storage. FA accumulation was higher in samples stored at –10°C, reaching 37 mg/g at 16 weeks; whereas, samples stored at lower temperatures showed 3 mg/g even after 24 weeks of storage. The extractable myofibrillar protein yield decreased around 50% at the end of the storage time in samples stored at –18 and –70°C. The remaining insoluble protein fraction was partially solubilized by SDS, urea and mercaptoethanol. Therefore, non-covalent and covalent interactions were involved in protein aggregation during storage. Samples stored at –10°C could not be assayed after 16 weeks of storage due to excessive tissue disruption It is accepted that protein denaturation during freezing results from dehydration and concentration of solutes. However, the type of protein interactions must be considered in order to increase shelf life.
Session 46G, Muscle Foods I
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