Histological structure of striped catfish (Pangasius Hypophthalmus) skin from different body size (age) and its relation to the quality of gelatin based on the melting point

Gelatin is a protein derived from collagen denaturation. Currently, fish gelatin has been developed as an alternative to halal gelatin. Fish gelatin can be extracted from the skin of several fish including striped catfish ( Pangasius hypophthalmus ), because the skin’s connective tissue contains a lot of collagen. In industrial applications, melting point is a very important characteristic of gelatin. The biological factors of raw materials such as the size or age of fish are thought to influence the content of collagen, thereby affecting the melting point of gelatin. The aim of this study was to compare the histological structure of the striped catfish skin at different body sizes, especially the observation of collagen in the skin’s connective tissues and to determine its relationship with the quality of its gelatin product based on melting point. The gelatin pre-treatment was performed using acid-base treatment, extraction with distilled water (55°C) were conducted prior to melting point measurement. The results of histological analysis showed that the connective tissue in the skin of larger fish contained thicker stratum compactum and thinner of stratum spongiosum. The melting point of large catfish skin gelatin has a higher melting point (25.5 °C) than the smaller size (24 °C).