Effect Of Storage Temperature On Postharvest Quality Of Fresh Walnut

Fresh walnut is rich in nutrition and crisp in taste.The walnut fruit with green husk is an important form of fresh walnut for sales at present.However,the walnut fruit is prone to browning and cracking,which will affect the taste and nutritional quality of kernel during storage.Low temperature storage has a positive effect on delaying browning and senescence of fruits and vegetables,but there are few reports about the effects of different low temperature storage on the quality of walnut fruits in cold storage and shelf life.In this experiment,walnut fruits stored at different temperatures(0,2,5,8?)were determine the differences of sensory quality,antioxidant physiological indexes of different parts and kernel quality during cold storage period,as well as the sensory quality of walnut fruits during shelf life at 20?after cold storage at different temperatures,which will provide the theoretical basis and application technology for the rapid development of fresh walnut industry.The main conclusions as following:(1)Among the four temperatures treatments,0?maintained the sensory quality and color of walnut fruit better during storage.The appearance color of walnut fruit at 0?kept the best and the cracking rate,soft browning rate and browning index of green peel at the end of storage were significantly lower than those at 2?.The L^*value of green peel decreased by 3.88 being significantly less than that at 2?and the?E^*value was 5.62with the smallest change compared with those at 2?.(2)During different cold storage periods,the POD activity,PPO activity,total phenol content and H₂O₂content of walnut fruit outside were higher than those inside,while O₂^-·production rate,MDA,GSH and GSSG content were lower than those inside;the H₂O₂content,O₂^-·production rate,the contents of MDA,soluble total sugar,free proline,GSH and GSSG of calyx end were higher than those of stem end.(3)Low temperature of 0?delayed kernel rancidity and maintained kernel quality better,whose soluble protein and crude fat content were 18.58 mg·g^-1and 60.08%,being significantly higher than those at 2?,as well as the AVand PV were significantly lower than those at 2?.(4)During different low temperature storage,the browning index,soft browning rate and cracking rate of"Xifu No.1"walnut fruits were were significantly lower than those of"Qingxiang"walnut fruits,and their sensory quality was better.Dring shel life of 20?,the appearance,browning index,fruit cracking rate and soft browning rate of walnut fruit after0?storage were significantly lower than those at other temperatures.In conclusion,0?is the suitable storage temperature to maintain the sensory quality of walnut fruit during cold storage and shelf life,and"Xifu No.1"fruit has better sensory quality during shelf life.