Thermal Denaturation of Muscle Proteins from Male and Female Squid (Illex argentinus) at Different Sexual Maturation Stages. A Differential Scanning Calorimetric Study

The influence of both sex and sexual maturation stage of specimens on the thermal behavior of muscle proteins was investigated. Differential scanning calorimetry (DSC) thermograms of whole muscle of female squids showed four endothermic transitions [peak temperature maximum (T max), 45.9, 56.8, 67.2, and 79.2 °C]. The DSC thermograms of whole muscle of male squids showed three transitions (T max, 47.9, 56.8, and 79.2 °C). The T max of 67.2 °C, present only in female squid muscle, was related to sarcoplasmic proteins. Myosin and paramyosin contributed to the first transition, connective tissue to the second transition, and actin to the last transition. No major differences were observed in T max values that were related to the sex and sexual maturation stage of specimens. The lowest denaturation enthalpy (ΔH) was found in muscle from immature females. Independently of the sex and the sexual maturation stage of specimens, no major changes were observed in either T max or ΔH values during frozen storage of squids. Keywords: Squid muscle; thermal stability; myofibrillar proteins; sexual maturation stage; differential scanning calorimetry