Effects of organic acid on the physicochemical properties of gelatine extracted from Fringescale sardinella (Sardinella fimbriata) bones

Gelatine from marine sources especially from the fish becomes a popular alternative to replace the commercial gelatines from bovine and porcine. Fringescale sardinella (Sardinella fimbriata) is commonly used in the fish processing industry and has a high potential to produce gelatine from its by-products. The extraction of gelatine is one of the most important steps that influence its functional properties. Inorganic acid was commonly used in the extraction, however, nowadays it faces some issues due to health safety and its effect on the environment. The aim of this study was to assess the effects of organic acid (fruit vinegar) as a replacement for inorganic acid (hydrochloric acid) during extraction on the physicochemical properties of S. fimbriata gelatine. The extracted gelatines were characterized in terms of their physico-chemical properties such as the yield percentage, gel strength, melting point, molecular weight, structural composition, and amino acid analyses. Results showed that gelatine extracted with organic acid demonstrated low yield percentage (2.9±0.01%) and poor gel strength (75.9±1.06 g) and melting point (22.0±1.00°C) values compared to the standard. This gelatine also demonstrated a low amount of proline and hydroxyproline contents, which were 43.77±8.21 g/mg and 34.99±6.50 g/mg, respectively. Overall findings have suggested that different types of acid used in the extraction resulted in different physico-chemical properties of the gelatine. Such findings suggested that S. fimbriata bone hold the potential to be an alternative source for vast applications in industries. Further studies may focus on different concentrations of acid used in the extraction process. Such findings will help to improve S. fimbriata bone gelatine properties for extended uses in various industries.