| In this experiment,Anyue Eureka lemon was used as materials to optimize post-harvest ethylene degreening treatment conditions.The effects of postharvest ethylene de-greening on the quality,storage characteristics and peel pigment metabolism of Eureka lemon were studied.The following are the main experimental results:(1)Screening the optimal conditions for post-harvest ethylene greening Eureka lemons.A single factor and orthogonal test method were used to obtain the final comprehensive score by the entropy weight method,and the temperature,ethylene concentration,2,4-D concentration,and de-greening time of post-harvest ethylene de-greening Eureka lemons were optimized.The test results show that the optimal de-greening temperature is 28 ° C,the ethylene concentration is 5 mg / L,and the concentration of 2,4-D is 30 mg / L.Under this optimized condition,the color index is 5.96-6.00,and the detachment rate is2.97-3.63%,the overall score is 0.87.After the de-greening,2,4-D contents remains below the national standard.(2)In the test,5 mg / L ethylene was used to de-green the lemon for 5 d at 28 ?.The changes of the main quality indicators of the peel and pulp were analyzed,and the quality of the lemons treated with de-greening and bagging were compared.The results showed that the hardness of the post-harvest fruit was significantly lower than that of the control group and the bagging group(p <0.05),and the a * value,carotenoids,total phenols,flavones,and malondialdehyde in the peels increased significantly(p <0.05),there was no significant change in L * and b * values.There were no significant changes in total acid,Vc,TSS,total phenol,and malondialdehyde in the pulp,and the flavonoid content increased by 14.28%.Post-harvest ethylene degreening treatment can effectively improve lemon peel color and lemon fruit quality.(3)In this experiment,lemons that have been de-greened with ethylene were stored together with bagged lemons at(9 ° C ± 1 ° C)for 13 weeks.The weight loss rate and the hardness were calculated.Fruit juice was measured for total acid,ascorbic acid,TSS,malondialdehyde,and volatile flavor substances in the peel.The results showed that total ethylene acid,ascorbic acid,TSS,weight loss rate,malondialdehyde,and volatile flavor substances all showed higher levels during storage,and the hardness showed lower levels in the early stage of storage,and the hardness was greater than Control group.Post-harvest ethylene de-greening treatment can improve lemon peel color and fruit quality,and ensure its storage quality,which can meet market demand outside the lemon ripening season.(4)In this paper,the effects of pre-harvest bagging and post-harvest ethylene de-greening on Eureka lemons were examined by examining pigment content and related gene expression.The results showed that both treatments reduced the number of chloroplasts and the content of chlorophyll.However,these two methods resulted in the differential expression of PSY1 and PSY2,which led to the difference in the major carotenoid phytoene.Differential expression of NYC results in differences in the content of chlorophyll a and chlorophyll b,resulting in differences in a * values.More interestingly,we found that the degradation of chlorophyll made the color of carotenoids appear,leading to the color of the peel changed from green to yellow. |
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