Effect of Dehulling Methods and Genotype on Chemical, Aflatoxin and Sensorial Indices for Walnuts

Dehulling is an important step in walnut processing that has considerable effect on the quality, chemical and microbial properties of walnuts. Improving dehulling can increase the quality of the final product. This research studied the effect of genotype and hulling method on walnut properties. Oneexperiment was performed as a factorial in a randomized complete block design with three replications in the food industrial laboratory of the Agricultural Research Center in Kerman. Chemical (fat oxidation, percent of moisture), aflatoxin and sensorial (color, taste, general acceptance) properties of seven genotypes (20, 21, 77, 88, 95, 211, 264) and their kernels were evaluated using two walnut hulling methods (industrial and traditional). The data were analyzed in and compared using a Duncan t test at p = 5%. The results showed minimum fat oxidation in walnut samples for genotypes 95 and 264 and in kernel samples for genotype 264. Moisture content in all samples was in the required range and the hulling methods for genotype 21 had minimum fat oxidation. The study showed that genotypes 77, 88 and 264 had the toughest skin and no aflatoxin was observed in these genotypes. Walnut samples 21 and 88 and kernel genotypes 24, 21 and 88 had the best taste and color. Hulling method had no significant effect on the sensorial properties of the walnut and kernel samples. Interaction between treatments showed that the industrial hulling method with genotype 21 was better for both walnuts and kernels. The sensorial and chemical properties of genotype 21 are more suitable for cultivation and, because there was no aflatoxin detected in industrial hulling, this method is most effective for processing walnuts.