Effect of thermal process on connective tissue from jumbo squid ( Dosidicus gigas) mantle

Abstract

The effect of two thermal treatments (fast freezing at −40 °C and vapor cooking at 100 °C) on connective tissue extract (CTE) from jumbo squid ( Dosidicus gigas) was investigated. Samples of CTE frozen at −40 °C were taken at 0, 3, 5 and 12 min. Also CTE was cooked at 100 °C and samples were taken at 0, 1, 2.5 and 5 min. Light microscopic observations of CTE after 12 min of freezing showed rupture of fibres. The CTE fibres showed agglutination during cooking time. The CTE insoluble fraction increased with freezing and cooking time. Maximum zeta potential value of untreated CTE was detected at pH 5.0 at +30 mV, meanwhile in the frozen CTE it was detected at pH 7.0 at +30 mV and two peaks (at pH 5.5 and 9.0) were observed at +20 mV in the cooked CTE. One endothermic peak was found at 105.9 °C in the untreated CTE, while in the frozen and cooked CTE the endothermic peaks were found at lower temperatures and enthalpies. Electrophoresis analysis of untreated CTE showed three bands. In the frozen CTE two bands appeared above 200 kDa, and in the cooked CTE, a 45 kDa band disappeared. These results suggest that during freezing and cooking processes there were modifications to molecular bonds that hold the integrity of the structure of the connective tissue of the jumbo squid mantle.