The Effects Of Hot Air Treatment On The"Jiefangzhong" Loquat Fruit Qulity During Postharvest Storage

Loquat fruit matures in the hot and rainy season, so it is susceptible to loss of nutritional and microbial decay. The main storage way of loquat fruits is cold storage, but low tempreture inereases the severity of flesh leatheriness. As a non-damaging physical treatment, post-harvest heat treatment has been applied to alleviate the chilling symptoms, control insect pests and disease, and to maintain fruit quality during storage. In this paper the effects of hot air treatment on the flesh leatheriness and the anthlaenose rot in loquat fruit and the possible mechanisms involved were investigated. The results are as follows:1. Loquat fruit were pretreated with different hot air treatments (38℃hot air with different times) and then stored at4℃to investigate the effect of hot air treatment on the quality of loquat furit(Eriobotrya japonica Lindl. CV Jiefangzhong). The results showed that38℃36h and48h hot air treatments delayed the decrease of TSS and the extractable juice content, prevented the increase of lignin, firmness, membrane leakage and internal browning index, reduced the rot occurrence of loquat fruit, maintained the eating quality. Compared with these two treatments,38℃48h was batter than38℃36h, but slight heat damage occurred.2. Loquat fruit were pretreated with hot air treatment at38℃for36h and then stored at4℃to investigate the effect of hot air treatment on activities of active oxygen detoxifying enzymes, lignification and pectin content. This hot air treatment enhanced the activities of SOD and CAT in loquat fruit. And the accumulation of H2O2was inhibited by the hot air treatment. Meanwhile, the activities of PAL, PPO and POD were enhanced and the accumulation of lignin was inhibited by the hot air treatment. Therefore this treatment alleviated the chilling symptoma of lignification. In addition, this treatment delayed the decline of the activity of PG, maintained highter level of water-and CDTA-soluble pectin and lower level of Na2CO3-soluble pectin. These results indicated that hot air treatment could alleviate the chilling symptoms of lignifieation.3. Loquat fruit were pretreated with hot air treatment at38℃for36h and then stored at20℃to investigate the effects of hot air treatment against anthracnose rot caused by Colletotrichum acutatum. Results showed that it significantly inhibited natural decay incidence and significantly reduced the lesion diameter and disease incidence in artificially inoculated samples. The hot air treatment accommodated the activity of SOD and CAT in the storage, resulted a higher level of H2O2in the earlier period and a lower level of H2O2in the later period of incubation. At the same time, this treatment induced the activities of PAL and β-1,3-glucanase, stimulated synthesis of lignin, thus elicited disease resistance. Moreover, the hot air treatment significantly inhibited mycelial growth and spore germination of C. acutatum directly, leading to lower anthracnose rot of loquat fruit.