Quality Profiling and Estimation of Total Phenols, Flavonoids, Flavonols and Antioxidative Potential of Walnut kernel (Juglans regia) from Kashmir valley

Present research study was carried out with four walnut (Juglans regia L.) genotypes viz. KG (Kulgam), CS (Char-e-Sharief), KW (Kupwara) and TM (Tangmarg) from major walnut producing areas of Kashmir valley. The aim of the study was the selection of superior genotypes having better quality nuts and kernels with higher antioxidant potential, for its exploitation at farm and consumer level. Nut and kernel external quality traits were recorded. The results revealed that the nut weight ranged between 11.70 to 14.51g; nut diameter between 9.60 to 14.27mm; nut length between 17.40 to 20.51mm. The maximum variability was observed in nut weight, kernel weight, kernel recovery, nut length and nut diameter. The fat content accounted for more than 60% of walnut kernel weight and ranged between 49.83 to 83.76%. The antioxidant potential, proximate and mineral composition, total phenolic content, flavonoids, as well as, flavonols, were all evaluated. Mineral content; zinc (Zn), iron (Fe), manganese (Mn), copper (Cu) magnesium (Mg) were determined. The Total Phenolic Content varied between 19.8 to 50.19mgGAE/g while the total flavonoid and flavonols ranged from 188.5 to 815.08mgQE/100mg and 3.46 to 7.77mgQE/g respectively. The walnut extracts (0.5mg/mL) showed 82.60 to 97.19% DPPH (2,2-diphenyl-1-picrylhydrazyl) scavenging activity. This study demonstrates that owing to maximum nut and kernel weight, as well as, nut recovery, better free radical scavenging properties and higher phenolic profile of KW (Kupwara) extract, this genotype seems to serve as a potential and promising one for production of walnut on large scale to avoid non uniformity.