Phenolics Content, Antioxidant Activity and Color of Green Walnut Extracts for Preparing Walnut Liquor

Different extracts prepared from green fruits of 'Sibisel 44' walnut cultivar were investigated for their total phenolics and flavonoids, antioxidant activity, individual phenolics content and colour component. Extracts were prepared using three variants, to analyze the effect of solvent concentration and sugar addition on properties of green walnuts extracts. The antioxidant activity of alcoholic extracts was investigated by the 2,2'-diphenyl-I-picrylhydrazyl (DPPH) radical scavenging method while total phenolic content was determined by using the Folin-Ciocalteu assay. Seventeen individual phenolics were detected and quantified by using HPLC in walnut green fruit extracts. For total phenolics and flavonoids extraction from green walnut fruits 70% ethanol was more efficient. Highest concentration was found in samples with 70% ethanol for gallic, vanillic, chlorogenic, caffeic, syringic, salicylic, ellagic acids, juglone, catechin, epicatechin, myricetin, and quercetin. The use of 40% ethanol led to a significant increase of ferulic acid and rutin content, while the greatest amount of rutin was extracted using 40% ethanol and sugar.