Preliminarily Study on Hydroxyproline Content of Purple-spotted Bigeye (Priacanthus tayenus) Scaly Skin and Its Gelatin Quality (Early view)

Abstract

The investigation of alternative raw materials for gelatin production from fishery industry by-products has gained attention due to the increasing demand for gelatin and the importance for sustainable practices. This study aims to determine the optimal concentration of hydrochloric acid (HCl) for mineral removal during pretreatment, assess hydroxyproline content at various processing stages, and characterize the resultant gelatin. The methodology involved pretreatment the materials with 0.1 M sodium hydroxide (NaOH) to remove non-collagen proteins, followed by mineral extraction using varying HCl concentrations (0.25, 0.5, 0.75, and 1 M). The process included swelling in 0.2% citric acid for 12 hours and gelatin extraction at 65°C for 7 hours. The results indicated that 0.25 M HCl was most effective for mineral removal. The hydroxyproline analysis showed an insignificant increase (0.088-0.103 mg/ml) from the pre-treatment stage to the final gelatin product. The physicochemical properties of the liquid gelatin, including yield (6.5 ± 0.39%), pH (6.55 ± 0.11), and gel bloom strength (174 ± 8.54 blooms) conformed to Gelatin Manufacturers Institute of America (GMIA). Functional groups confirmed the presence of gelatin-specific, such as amides A, B, I, II, and III. The molecular profile comparable to commercial gelatin, with ?1 chains at 130 kDa, ?2 chains at 115 kDa, and ? chains at 235 kDa. The gelatin derived from the scaly skin of purple-spotted bigeye exhibits promising attributes, aligning with commercial standards, and highlights the potential of fishery by-products as a sustainable and halal source of gelatin.