Studies on the Mechanism of Softning of Fish Bone by Cooking

在日本，小鱼被当作传统的海鲜或“tukudani”来吃，整条鱼包括骨头。本研究旨在阐明骨在醋腌和水煮过程中物理性质和成分的变化。通过感官试验和仪器测量，评价了鱼骨在醋中腌制或在水中加热后的软化程度。马鲛鱼椎体在醋酸溶液中固化30 min后硬度下降。在这个过程中，骨中钙的洗脱率很高，但蛋白质的洗脱率很低。鱼骨在常压下在水中加热120分钟，通过Reometer测量鱼骨硬度下降。在烹饪过程中，25%的蛋白质从骨头中洗脱到水中，但钙和其他矿物质几乎没有在水中洗脱。在酸性溶液中烹饪，骨骼在短时间内发生软化，蛋白质和大量矿物质都从骨骼中洗脱出来。组织学结构观察表明，在水蒸煮和酸性溶液腌制过程中，骨基质发生了显著变化。通过电扫描显微镜观察，在水或酸溶液中蒸煮时，骨表面可见明显的胶原纤维束，酸固化时，骨表面可见无定形物质。在光学显微镜下，皮质骨和海绵骨的横截面结构变得更加粗糙。本研究揭示了鱼骨在烹调过程中硬度的变化以及鱼骨中蛋白质和无机化合物的行为。我们认为鱼骨的软化是由于鱼骨中蛋白质和矿物质的分离造成的。

Small fishes are eaten as traditional dishes of marine or "tukudani" with a whole including bones in Japan. This study was cried out to clarify the changes of physical properties and components of bone in vinegar-curing or cooking in water. Softening of fish bone cured in vinegar or heated in water was evaluated by sensory tests and instrumental measurements. The hardness of horse mackerel vertebra decreased in 30 min after curing in an acetic acid solution. In this process, high percentages of calcium eluted from bone, but little protein was eluted. When fish bone was heated in water at atmospheric pressure for 120 min, hardness of bone decreased by measurement of Reometer. During cooking, twenty five percent of proteins eluted from bone into water, but calcium and other minerals hardly eluted in water. In the case of cooking in acidic solution, softening of the bone occurred in short period, both of protein and much minerals eluted from bone. Histological structure observation showed that bone matrix changed remarkably during cooking in water or curing in acidic solution. By the electrical scanning microscopic observation, the bundle of collagen fiber in the surface of bone was showed clearly during cooking in water or in acid solution and an amorphous substance on the surface of bone during acid curing. The cortical bone and the spongy bone became more coarse structure in cross sections by optical microscope.This studies revealed the changes in hardness of fish bone and the behavior of protein and inorganic compounds in bone during cooking. We assumed that the softening of bone occurred in because of separation of protein and minerals in fish bone.