Toyo Institute of Food Technology, Kawanishi, Hyogo 666-0026, Japan
The change of tissue strength in prawn by heat treatment (boil, retort (121°C, F0=6)) was studied. The physical and chemical properties of prawn after heat treatment were measured by X-ray computerized tomography (CT), scanning electron microscopy (SEM) and environmental scanning electron microscopy (ESEM), and chemical analysis for percentage of gelatin in collagen. According to the results of the strength of muscular tissue, the retorted sample was the softest. By measurement of X-ray CT, the muscle density of the retorted sample was lower than that of the boiled sample. The muscle fibers of raw and boiled samples were wrapped by connective tissue, but the retorted sample was partially-removed was viewed under ESEM. The gelatinization rate of collagen in the retorted sample was higher than that of the boiled one. It is suggested that the softness of prawn tissue by sterilization is caused by gelatinization of collagen.