Degradation of fish gelatin using hot-compressed water and the properties of the degradation products

The degradation of fish gelatin using hot-compressed water was investigated. The hot-compressed water treatment resulted in the degradation of fish gelatin into peptides, and the number of the peptides increased with increasing the temperature. The distribution of amino acids in the product mixture indicated that hot-compressed water treatment at 240°C resulted in a high level of amino acid degradation, and the highest concentrations of free amino acids was at 220°C. Lysinoalanine, which is toxic, was rarely generated by hot-compressed water treatment at higher temperature range. Additionally, the optimum temperature for the hot-compressed water treatment with respect to the angiotensin I-converting enzyme inhibitory was at 180°C. These analyses demonstrate that the degradation of fish gelatin with hot-compressed water could be used to generate functional materials.