Study on Total Phenolic, Flavonoid and Antioxidant Capacity of Fish Singgang Extracts

Aim: To evaluate the ash and moisture contents, total phenolic content, total flavonoid content, and antioxidant potential of Terengganu singgang extracts. Study Design: Experimental study. Place and Duration of Study: Central Laboratory, Tissue Culture Laboratory, Universiti Sultan Zainal Abidin, Terengganu between April 2019 and July 2019. Methodology: Samples comprised three types of singgang dishes, which were prepared, cooked, and then extracted with distilled water and ethanol (EtOH) in different strengths, 50%, 70%, and 100%. These singgang samples were chub mackerel (ST), Indian mackerel (SK), and a control sample with no fish(SC). Extracts were analyzed for their moisture and ash content. Also, the total phenolic content (TPC) was assayed using Folin-Ciocalteu reagent, while total flavonoid content (TFC) using AlCl3 colorimetric assay, and antioxidant activity using 1,1-Diphenyl-2-picrylhydrazyl (DPPH). The total antioxidant capacity (T-AOC) was also evaluated. Results: Experimental assays showed that the SC sample extracted in 100% EtOH produced the highest yield (3.7%). SK samples were lower than SC and ST in moisture content and ash content with 94.21%, 96.37% and 93.03% moisture content and 0.85%, 0.71%, and 0.96% ash content. Meanwhile, the extract of ST in 100% EtOH yielded the highest TPC (315.0 mg GAE/100g) and T-AC (8.8 U/mL) but the lowest in DPPH scavenging activity (12.2%). On the other hand, the extract of SK in 70% EtOH gave the highest TFC with 6485.3 mg QE/100g. The correlation of TFC and TPC with DPPH and T-AOC assays was positively significant. Conclusion: In conclusion, the ST extract yielded the best antioxidant capacity.