| Research Abstract |
Recently, deficiency of calcium intake, which is a factor in osteoporosis, has become a problem in Japan. Japanese have traditionally consumed fish in large amounts, and small fish, which can be eaten with bones included is considered to be an important source of dietary calcium. In this study, changes in the physical properties and composition of fish bone by boiling were studied to obtain basic information for more effective nutritional utilization of fish bone. Bones of horse mackerels were boiled in water for several hours, and their breaking strength was measured with a rheometer. Inorganic components of the horse mackerel bones were measured by ICP-AES.When horse mackerel bones were cooked in water, the maximum force needed to compress them to 80% of their original thickness decreased rapidly after 30 minutes and continued to decrease thereafter with the cooking time. The weight of fish bone decreased after 30-minute cooking and continued to decrease over a cooking time of 180 minutes. The water content of the fish bone increased slightly with the cooking time. The protein content of the bone decreased, but that of the cooking water increased, with the increased in the cooking time. Horse mackerel bones cooked in water were softened progressively with the cooking time, but most of their calcium content was remained in the bones. The softening of horse mackerel bones cooked in water is probably explained by elution of part of the proteins contained in the bones into water and consequent changes in the bone texture.
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