Optimization of cobia fish (Rachycentron canadum) gelatin extraction with response surface methodology

Cobia fish or often called sea cork fish, is a fish that has thick meat which is nutritionally equivalent to salmon meat. Cobia fish is usually sold in the form of fish fillets and the bones becomes solid waste, which has the potential to be a raw material for fish gelatin. Gelatin is a bone and skin collagen hydrolysis product that can be used for food and nonfood industries. The quality of fish gelatin is influenced by the extraction process, such as acid concentration, temperature, and extraction time. This study aims to determine the effect of hydrochloric acid concentration, temperature, extraction time, and the optimal process of making cobia fish bone gelatin using the response surface methodology with the Box Behnken model. The data was processed using Design Expert 11 software. The model suggested by the software was the cubic model. The optimum extraction conditions obtained were using a concentration of 5.53% hydrochloric acid, a temperature of 90oC, and a stirring time of 6.42 mins would produce a yield of 12.38% and gel strength of 229.14 bloom. The verification results by extracting cobia fish gelatin with optimum conditions obtained a yield of 11.22% and gel strength of 227.60 bloom. The proximate analysis of cobia fish gelatin extracted under optimum conditions was found to contain 6.43% water content, 8.27% ash content, 4.65% fat content, 68.47% protein content, and 12.18% carbohydrate by different. Cobia fish gelatin microstructure is in the form of thick strands with a soft sponge.