STUDY ON THE PROPERTIES AND UTILIZATION OF FISH SCALES

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A large amount of sardine scales, which canbbe easily peeled off, are piled up in a fishing port at landing. These scales are lightly washed with water, dried and stored. Their uses are restricted only to feeds and fertilizers. In recent years, collagen has been widely studied and employed as a biopolymer. It is considered that fish scales are important as one of these collagen materials. Because of having been useddfor evaluating fish age, scales have been studied almost exclusively from the viewpoints of morphology, i.e., the form and growth, Thus there have been reported few studies on the components of fish scales. In this study, the general properties of sardine scales, characteristics of fish scale protein and effective utilization of the same.(1)The contents of protein and total ash in sardine scales in terms of dry matter were respectively 23.6% and 68.3%. Calcium salt could be completely removed from fish scales by immersing the scales in a dilute solution of hydrochloric acid … More only foe a short period of time. It is therefore considered that the state of the calcium/collagen complex contained in sardine scales might largely differ from those contained in cattle and chicken bones.(2)Observation under a scanning electron microscope indicated that a purified scale consisted of collagen fibbrils laminated on each other to form a lattice. Different fromcattle skin, no network structure of fiber bundles was observed.(3)The amount of fish scale gelatin extracted from the fish scale protein prepared from dry sardine scales and its properties were studied. In the case of the fish scale protein, the maximum amount of gelatin could be extracted by treating with alkali for 3 days (i.e., gelatin extracted at 60 C ; 38.9%, total gelatin extracted : 71.6%). In the case of the pig collagen sample, on the other hand, the maximum of gelatin could be extracted by treating with an alkali for 14 days (i.e., gelatin extracted at 60 C : 29.4%, total gelatin extracted : 48.3%).(4)Fish scale protein, which mainly comprises collagen I,may be applicable to gelatin, feeds, etc. To use the fish scale protein for these purposes, however, it is required to remove calcium compounds which amount to more than 60% in terms of dry matters. Accordingly, it is seemingly desirable to effectively utilize fish scale protein by taking advantage of the characteristics of collagen as a biopolymer or to employ or to employ the scales as a molding material through the application of the characteristic form therefore. Less