Phenolic content and free radical scavenging activity of herbal seasoning enriched with oyster mushroom (Pleurotus sajor-caju) powder

S. Saiful Bahri, W.I. Wan Rosli and M. Kasmah

Abstract
Mushrooms have received great attention for their health benefits due to their polyphenols content and the related antioxidant activity. Edible mushrooms are known as low calorie functional foods that suit to the design of healthy diet food patterns. The aim of this work is to evaluate the antioxidative activity of methanolic extracts of the herbal seasoning (HS) enriched with Pleurotus sajor-caju (PSC) powder in different assays, namely, 2,2-diphenyl-1-picryhydrazyl (DPPH) free radical scavenging activity, ferric reducing scavenging power (FRAP) and total phenolic content (TPC). Chemical compositions were determined by standard AOAC methods. Six different formulations with different levels of PSC powder at 0% (A), 20% (B), 40% (C), 60% (D), 80% (E) and 100% (F) to substitute coconut milk powder were used in this study. The methanolic extracts of HS(F) showed the highest antioxidant activity in scavenging DPPH free radicals (54%) than the control treatment HS(A) (43%). Meanwhile, the reducing capacities of PSC powder incorporated at different levels were in the range of 23.57 – 60.52 mg ascorbic acid equivalents (AAEs)/g extract. Among all samples, HS(F) had the highest total phenolic content [1,823.84 ± 0.84 mg gallic acid equivalents (GAEs)/g]. Overall, the antioxidant activities in DPPH and FRAP increased with increasing concentration of PSC powder in the formulations. The high content of ash which was recorded in PSC based HS might be contributed by some minerals present in PSC powder in the HS. This study indicated that PSC powder exerts some antioxidative capacities, thus it can be potentially used as a natural antioxidant in processed food products.

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