Effects of chemical hydrolysis operating parameters on the production of antioxidant from fish waste

Abstract

Instead of being inappropriately disposed and causing sanitary and environmental problems, underutilised fish waste can be processed into value-added products such as antioxidants which can be used for pharmaceutical, medicine and agriculture purposes. In this study, chemical hydrolysis was chosen as it was more suitable for industrial scale, shorter time and cheaper compared to enzymatic hydrolysis. However, information on the operating parameters of fish waste chemical hydrolysis was scarce. Therefore, the objectives of this study were to investigate the effect of types of solvents used, the concentration of HCl, demineralization time and deproteinization time on the production of antioxidant from fish waste via One Factor in Design Expert. Demineralization was carried out by immersing 10 g of fish waste in 0.2 M to 1.0 M of Hydrochloric acid (HCl) for 30 min to 150 min at room temperature and continued stirring at 150 rpm. Deproteinization occurred by introducing the sample into 1.0 M of Sodium Hydroxide (NaOH) for 30 min to 150 min at 60 ℃ and continued stirring at 150 rpm. These samples were then washed with distilled water and oven-dried at 60 ℃ for 5 hours. 2, 2-Diphenyl-1-picrylhydrazyl (DPPH) and Total Phenolic Compound (TPC) assays were used to analyze the availability of antioxidant by calculating the percentage of antioxidant activity and Gallic Acid Equivalent, GAE (g/L). The best concentration of HCl used was 0.72 M at 92 min of demineralization, 70 min of deproteinization and ethanol as the suitable solvent used in DPPH and TPC assays. These valuable findings are beneficial for further works on enhancing the production of antioxidant from marine sources like fish waste.