Effects Of AVG And CTM Treatments On Superficial Scald In ’Starking’ Apple

Superficial scald is a common physiological disease of apples during low temperature storage,which often causes significant economic losses.The chemical drugs 1-MCP and DPA are used to prevent superficial scald,but the search for new natural,safe and non-toxic measures is becoming a hot spot of concern.Aloe vera gel(AVG)and Chinese traditional medicine(CTM)as pure plant extracts have the characteristics of cheap and easy to obtain raw materials and simple production process.In this experiment,‘Starking’ apple fruit was used as experimental materials,the effects of fruit quality,antioxidant capacity and occurrence of superficial scald under room and low temperature storage conditions were compared with those of DPA and 1-MCP treatments,and the mechanism of scald control was discussed,which laid a foundation for future commercial applications.The main results of the study are as follows:(1)Both AVG and CTM treatments can maintain higher fruit firmness,the fruit firmness of AVG treatment was higher than that of CTM treatment,but it was less than that of 1-MCP treatment.AVG and 1-MCP treatments significantly reduced SSC levels than control group,and there was no significant difference in SSC between other treatments.(2)The statistical analysis of the incidence and index of superficial scald showed that AVG treatment could not effectively control the occurrence of superficial scald,but increased the incidence of fruits;CTM treatment could significantly reduce the incidence of superficial scald,but its effect was not as well as 1-MCP and DPA treatments.(3)AVG and CTM treatments decreased the release of ethylene and the content ofα-farnesene and CTols in the early stages of room temperature storage and low temperature storage,CTM treatment significantly reduced ethylene release,α-farnesene and CTols content during the later period of low temperature storage but DPA and 1-MCP treatments gave the best effects.There were significant differences in the expression of key enzyme genes for ethylene synthesis among the treatments.(4)All treatments except AVG can reduce the superoxide anion production rate,H2O2 and MDA content during storage at room temperature and low temperature.1-MCP treatment had the best effects.(5)The determination results of DPPH and total phenol content show that all treatments can maintain high antioxidant capacity and total phenol content in the early stages of storageat room temperature and low temperature.Among them,1-MCP treatment has the best effect.DPPH clearance and the total phenol content was significantly reduced,and CTM treatment was better than AVG treatment,followed by DPA and 1-MCP treatment.(6)AVG treatment can significantly increase the activity of CAT,APX and SOD,and reduce the activity of PPO during storage at room temperature;during low temperature storage,the effect of CTM treatment is more advantageous than AVG treatment.CTM can continuously keep the antioxidant capacity of the peel during long-term low-temperature storage.These results show that CTM treatment is better than AVG treatment in the prevention of superficial scald and the occurrence of superficial scald is closely related to the oxidation of ethylene,α-farnesene,MDA content and PPO activity.