Walnut (Juglans regia L.) kernel postharvest deterioration as affected by pellicle integrity, cultivar and oxygen concentration

•The role of pellicle and low-oxygen storage on kernel consumer quality was studied.•Shelling caused pellicle disruption and accelerated kernel browning.•Walnut oil degradation was favored by pellicle damage occurring during shelling.•Impact of shelling damage was related to genotype.•‘Howard’ kernel color benefitted from oxygen equal to or lower than 3 kPa.