Aggregation of minced hake during frozen storage.

摘要

Aggregation in minced hake muscle (Merluccius merluccius) during storage at -20 degree C was studied in conditions where there was progressive deterioration of functionality and texture as measured by apparent viscosity and shear resistance. Natural actomyosin was extracted with 0.6M NaCl over a period of 49 wk. Insoluble residue was extracted successively with 2% SDS and 2% SDS plus 5% beta-mercaptoethanol (ME) solutions. SDS-PAGE performed on extracted fractions showed a 75% decrease in 0.6M NaCl extractability by the end of storage. Initially all remaining precipitate was extracted in 2% SDS. Although the amount extracted in this solution increased as storage time progressed, its proportion decreased, accounting for as little as 40-50% ofthe protein aggregate by the end of storage. Proteins most involved in formation of aggregate (not extracted in 0.6M NaCl) were myosin and actin. Neither of these proteins was fully recovered in the fractions extracted with 0.6M NaCl, 2% SDS, or 2% SDSplus 5% ME, and therefore it was inferred that they were forming part of the aggregates, bound by covalent bonds.