Evaluation of antioxidant and antimicrobial activity of peppermint, ginger and rosemary extracts

Chemical spoilage of food products can lead to consumer rejection of the product. Therefore, the use of natural antioxidants is of wide importance and potential use to prevent oxidation of nutrients in food products and subsequently maintain the quality of the products and extend shelf life. The present work focuses on the evaluation of the antioxidant power of peppermint, ginger and rosemary. Peppermint extract showed a highest phenolic content (264.74±12.35 mg GAE/g) followed by ginger (101.31±0.89 mg GAE/g) and rosemary (126.58±0.67 GAE/g) while, while rosemary extract has a highest flavonoids content (169±0.11 mg/g) and the peppermint showed the least content (56.35±0.31 mg/g). The highest antioxidant activity presented by rosemary extract with IC50 = 24.5 μg/ml followed by peppermint extract with IC50:109.7 μg/ml) and ginger extract with IC50 = 536 μg/ml. HPLC profile showed 13 different phenolic compounds with high concentration of ellagic acid, rutin, p-hydroxybenzoic acid in rosemary extract. while ellagic acid showed the highest concentration in both ginger and peppermint extract. All tested extracts showed good antimicrobial activities against different pathogens with varying inhibition diameters. Peppermint, ginger and rosemary extracts have high potential for use in food production as natural preservatives.