Changes in physicochemical properties and microstructure of dried squid during softening treatment

Dried squid were prepared at 4 or 40 °C and softened first in water and then in alkaline solution. The physicochemical and structural changes in the dried squid during the softening treatment were examined. A significantly higher wet weight was observed for the 4 °C-dried squid during the softening treatment compared with the 40 °C-dried squid. The rupture stress and rupture energy of the 40 °C-dried squid were significantly higher than those of the 4 °C-dried squid during the softening treatment. The sodium dodecyl sulphate polyacrylamide slab gel electrophoresis (SDS-PAGE) pattern of the 4 °C-dried squid was almost the same as that of raw squid. The SDS-PAGE pattern of the 40 °C-dried squid showed many fragments of lower molecular weight. After soaking in distilled water the SDS-PAGE pattern of the 40 °C-dried squid did not change significantly; however, the SDS-PAGE pattern of the 4 °C-dried squid became the same as that of the 40 °Cdried squid. Histological analysis by light microscopy showed the formation of muscle fibre bundles in the 40 °C-dried squid. A higher water permeation was observed among the muscle fibres of the alkali-softened 4 °Cdried squid when compared with the alkali-softened 40 °C-dried squid.