Evaluation of the properties of tuna skin gelatin as a hard capsule material

Gelatin, which is thermally converted from collagen, is widely utilized in the pharmaceutical industry as a raw material for hard and soft capsules. The aim of this study was to produce gelatin from yellowfin tuna skin, the by-product of tuna processing, and determine the optimal concentration for hard capsule production. Capsules were prepared from the skin gelatin. The tuna skin gelatin was characterized as follows: pH 6.0, gel strength 191 g Bloom, water content 7.01%, ash content 0.92, setting temperature 22.3 °C, and viscosity 12,700 cP. A 20% gelatin solution was found to be the best concentration among the concentrations examined for hard capsule production, and gave a body capsule height of 19.4 mm, cap capsule height of 12.8 mm, weight of 0.07 g, disintegration time of 4.09 min, pH of 5.92, and moisture content of 12.0%. The results suggest that tuna skin gelatin can be an excellent source of hard capsule material.