Characteristics of gelatins extracted from fresh and sun-dried seawater fish skins in Indonesia

Sun-drying was carried out to dry fish skins of four species of seawater fish, namely yellowfin tuna, brown stingray, red snapper and white cheek shark, and the gelatins extracted from the skins were characterized in comparison to those of extracted from fresh skins. The fish skins were pretreated using 0.05 M acetic acid followed by extraction at 80oC for 2 h. The gelatin obtained was analyzed for yield, proximate composition, functional properties, and amino acid composition. Results showed that drying on brown stingray and red snapper fish skins significantly decreased gelatin yield. Gelatins from dried fish skins had higher crude protein, lower ash content and lower crude lipid. Drying led to decreased viscosity, increased gel strength, and no significant effect on melting point. Gelatin from dried skins showed a higher turbidity and darker appearance. It was observed that drying did not interfere with amino acid composition. This study showed that sun-drying seems to be a prospective method for preservation of fish skins.