Effect of Cooking Temperature on the Microstructure and Rheological Properties of Squid Mantle, Loligo duvaucelli

摘要

Texture profile analysis of fresh samples of Loligo duvaucelli upon cooking showed high hardness (11.53 kgf) at 50℃. This may be due to the loss of myofibrillar integrity. Fracture force (6.04 kgf) was also reasonably high at this temperature. Cooking treatment of 70℃ obtained a tender texture for fresh samples with a high cohesive value of 0.31 possibly due to gelatinization of the collagen fibrils. In the case of frozen samples the hardness due to myofibrillar conformational changes was observed at 45℃ that on progressive cooking to 80℃ showed a high value for cohesiveness (0.29) with a resultant tendering of the sample. This indicates that freezing and period of frozen storage are factors affecting the texture of the mantle tissue. The shift in cooking temperature in obtaining optimum values for hardness and cohesiveness in frozen samples compared to fresh samples can be thus explained. Histochemical analysis of the samples revealed progressive-structural alterations in tissue components of cooked mantle. The comparison of light micrographs showed several pores amid the muscle cells in the softened sample that are due to detachment of the muscle cells from the connective tissue. In cooked muscle tissue, heating decomposed the collagen to gelatin and thus, decreased the integrity between muscle cells, leading to muscle softening. An increase in temperature caused a continuous fiber shrinkage and disintegration of the muscle proteins. During cooking, the coagulation of sarcoplasmic proteins and disintegration of sarcoplasm was pragmatic. Conformational changes in myofibrillar and stroma protein during frozen storage and cooking, leading to aggregation and rendering the muscle harder and tougher, were observed during histochemical analysis and texture profile analysis.