Extraction And Determination Of Antioxidant Activities Of Phenolic Compounds In Defatted Perilla Seed Meal

Abstract

Perilla seed (Perilla frutescens) is an herb that usually used in cooking and traditional medicine. Defatted perilla seed meal (DPSM) is a by-product from extraction of perilla seed oil using screw press. This by-product might contain some bioactive compounds such as polyphenol that can be used as antioxidant. This research was conducted to study the extraction condition of polyphenol from DPSM which extracted using ethanol 70 % and 50 %, acetone 70 % and 50 %, nhexane, and mixture of hexane:ethanol (50:50 v/v). This study also determines the antioxidant activities of DPSM extracts. The proximate analysis showed that raw perilla seed contained 18.84 % crude protein and 28.63 % crude fat, while DPSM contained 27.11 % crude protein and 4.49 % crude fat. DPSM was extracted using solvents with different polarity at various extraction times. The total phenolic compounds of DPSM extracts were measured by Folin-Ciocalteu assays as well as antioxidant activities using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP). Longer extraction time yielded higher TPC and better antioxidant activity. Total phenolic content of DPSM extract which be extracted using acetone 70 % for 90 minutes (1031.99 ± 92.45 μmol GAE/100 ml) resulted in the highest yield. It was not significantly different (p<0.05) from extracting using ethanol 70 % for 90 minutes. While extraction using n- hexane for 30 minutes (58.92 ± 7.60) indicated the lowest yield but it was not significantly different from extracting using n- hexane for 60 and 90 minutes as well as hexane:ethanol for 30 minutes at p<0.05. Extraction using acetone 70 % for 90 minutes exhibited the high FRAP (1269.44 ± 134.45 μmol AAE/100 ml) and DPPH values (1029.52 ± 7.4 μM Trolox). While n- hexane extraction for 30 minutes showed the lowest FRAP (216.20 ± 33.13 μmol AAE/100 ml) and DPPH values (18.48 ± 1.65 μM Trolox). Another polar components and phenolic compounds that have high activity in DPSM extracts can influence the antioxidant capacities. Based on the results, it is likely that hexane or mixture of hexane:ethanol have low yield of phenolic compounds but the antioxidant activities were not always low. When the extraction processes using polar or nonpolar solvent, it is suggested to use another method other than FRAP and DPPH which more suitable to know the antioxidant capacity in DPSM extracts. To optimize the solubility of polar or non-polar compounds of DPSM, the continuous solvents can be used. This research is expected to explore more to know the application of this result into food products.