Comparative study of antioxidant and antimicrobial activity of different parts of lemongrass leaves and their application in the functional drink

Abstract

Purpose This study aims to compare the antioxidant and antimicrobial activity of different parts (tip, mid and base portion) of lemongrass leaves for application as a natural ingredient in the functional drink. Design/methodology/approach Lemongrass leaf powder was prepared from different parts of leaves and evaluated for nutritional composition. Additionally, the extracts of different portions of lemongrass leaves were analyzed for total phenolics, free radical scavenging activities, ferric reducing antioxidant potential (FRAP) and antimicrobial activities for their application in food products. Findings Tip portion of lemongrass leaf anticipated significantly (p < 0.05) higher contents of ash, protein, calcium, potassium and iron i.e. 6.2 mg/100 g, 18 mg/100 g, 340 ppm, 819 ppm and 32 ppm, respectively. Maximum (p < 0.05) phenolics (14.7 mg GAE/100 g), 2,2-diphenyl-1-picryl-hydroxyl (86.3%) and FRAP (200 mmol/100 g) were observed in lemongrass leaf tip methanolic extracts. Moreover, lemongrass leaf tip hydro-methanolic extracts portrayed maximum zone of inhibition against E. coli and Staphylococcus aureus i.e. 16.7 and 18.2 mm, respectively. Practical implications This study demonstrated higher antimicrobial and antioxidant activities of the tip of lemongrass leaves as compared with mid and base portions, hence suggesting its role in the improvement of physicochemical, antimicrobial and antioxidant properties of food products. Consequently, the application of lemongrass methanolic extract up to 10% remarkably enhanced the nutritional value and sensorial acceptance of the beverages. Originality/value The present research draws evidence from laboratory analysis of fresh lemongrass grown in Pakistan. The findings suggest that lemongrass methanolic extracts could be used as a nutritionally rich source of antioxidant activity in functional drinks.