Extraction process optimization for antioxidants, nutritional, physicochemical and functional properties in Fagopyrum esculentum Moench leaves of Himalayan region

Abstract

Buckwheat (Fagopyrum esculentum Moench, Polygonaceae) leaves, possess health promoting nutrients and bioactives. The current study focused on comparative assessment of the physico-chemical, nutritional, functional and phytochemical properties of fresh, oven dried (OD) and freeze dried (FD) variants of the F. esculentum Moench leaves and process optimization for extracting maximum bioactives. Response Surface Methodology employing homogenization-assisted-ultrasonication effectively optimized process conditions for extraction yield (27.243 %), total phenolic content (227.964 mg GAE. g−1), total flavonoid content (105.682 mg RE. g−1) and antioxidant activity (14.127 µg. ml−1) for OD leaf extract. Optimized extraction conditions were applied to fresh and FD leaves and variability in phenolic and flavonoid contents, antioxidant and metal chelating ability and targeted metabolites, quantified using High Performance Liquid Chromatography, was studied. FD leaves retained significant phenolics along with higher metal chelating ability whereas OD leaves showed greater antioxidant capacities. Metabolite profiling revealed that though FD leaves contained adequate vanillic, gallic, caffeic acid and catechin, OD leaves consisted of significantly higher amounts of chlorogenic, ferulic acid, and rutin. The eminence of Fagopyrum esculentum Moench leaves renders it as a natural source of food fortificant which can stimulate nutritional security and aid in economic and sustainable growth of underutilized crops of Himalayan region.