Optimization of enzymatic hydrolysis condition for amino acid and taurine production from Thunnus tonggol viscera as fish protein hydrolysates

Abstract

The common additives in cat food, particularly synthetic amino acid and taurine are commonly produced through chemical processes. This has triggered concern for long-term adverse health effects on cats. Hence, the demand for natural amino acid and taurine has increased. As a whole, this study aimed to produce amino acid and taurine in fish protein hydrolysates (FPH) from Longtail Tuna (Thunnus tonggol) viscera using bromelain and papain enzyme mixture. The main objective of this study was to optimize the enzymatic hydrolysis processing condition of Thunnus tonggol viscera towards high-quality FPH. The enzymatic hydrolysis process was done by combining the ground viscera with the enzyme mixture and this new mixture was then incubated to produce FPH. The FPH was first characterized for its physical properties, before it was optimized and compared to the commercial benchmarked fish flavour (BeFF). The optimization proses was conducted using response surface methodology where the responses analyzed were the amount of total protein (%), total amino acid (g/100g) and taurine (g/100g). From the optimization analysis, compared to BeFF, the optimize FPH contained twice the amount of total amino acid and taurine which were 136.10 g/100g and 0.55 g/100g. It was also found that the optimized FPH contained 15.4 % of total protein. The physical properties of the optimized FPH was comparable to BeFF with pH 4.01 and viscosity 1962 cP. The sensory evaluation on the smell and aroma strength of the optimized FPH shows that both were well accepted. The optimal processing conditions that contributed to the high production of protein, amino acid and taurine were found to be at a temperature of 47.6 °C, incubation time of 22 hours and 0.97 % of enzyme concentration. Taken together, the current data showed that the optimization study has successfully produced a high-quality FPH with high amount of protein, amino acid and taurine content. This study provides a new perspective on the manufacturing process of natural amino acid and taurine, and it also demonstrates the potential of these product to be used as fish flavour in cat food.