The Biochemical Mechanism And Regulation Of Senescence, Browning In The Postharvest ‘shenzhou Honey’ Peach

‘Shenzhou honey’ peach have a short shelf-life, and the most common method employed to delay ripening and increase their postharvest life is cold storage and ethylene regulators. However, after extended storage at low temperature some cultivars have alternated ripening processes, resulting in Flesh browning, a lack of juice and a woolly texture. In this study, we are discussed preliminarily the physiological and biochemical mechanism of fruit senescence and how to prolong the storage and reduce the flesh browning preservation technology using fresh-keeping storage technique.We chose ‘Shenzhou honey’ peach(Prunus persica(L.) Batsch cv. Shenzhou)of 2014 and 2015 as materials, determined the fruit quality, total phenol, MDA content and related enzyme activity changes of fruit under different postharvest conditions: 14 days at 20℃, 21 days at 0℃ followed by 7 days at 20℃. The results suggested: in the room temperature storage conditions, peach fruit appear flesh browning, began from maturation to senescence. In this time, relative conductivity and MDA content increased to the highest, cell happened membrane lipid peroxidation, membrane permeability increased, indicating peach fruit region of PPO and phenolic substances destroyed. In the case of aerobic oxidation, PPO catalyzed phenolic compounds into quinone, total phenolic content began to decline, PPO activity reached the highest, leading to flesh browning.During cold storage, the fruit firmness remained unchanged, the juice yield rose slowly, the relative conductivity and MDA content was relatively low, browning phenomenon did not appear, these showed that did not show symptoms of chilling injury during cold storage, fruit quality was good. When the fruit was transferred to the shelf life, the relative conductivity and MDA content increased rapidly. When the flesh browning happened on the first day of the shelf life, total phenolic content continued to decline, the total activity of PPO reached the highest; membrane lipid peroxidation was serious, produced a large number of free radicals, the SOD, CAT enzyme activity increased. This shows that ‘Shenzhou honey’ peach did not exhibit chilling injury symptoms during storage, but may cause metabolic disorders the related substances in fruit, the peach in shelf period showed the flesh browning phenomenon is serious.Peach fruit stored at room temperature appeared ethylene peak in 7-9 days, but did not appeared significant respiratory peak. Peach fruit show ethylene release peak stored in 20℃ shelf 3-4 days, appeared respiratory peak in 4-5 days. And compared with peach storage in room temperature, the peach of storage in low temperature appeared respiratory and ethylene release peak in advance, and the content was relatively higher. Cold storage could prolong the storage time, but enhanced respiratory and ethylene release rate in shelf life, shortening the shelf life.We used ‘Shenzhou honey’ peach of 2014 as the material, explored the effect of smart fresh with modified atmosphere packaging(MAP+SF) and ethylene sustained-release formulation with modified atmosphere packaging(MAP+ESF) treatments on the fruit quality of storage period and shelf life on the basis of low temperature conditioning(LTC). The results showed that the polyphenol oxidase(PPO) activity of SF+MAP treatment was significantly higher than CK treatment, while the flesh browning index was significantly lower than that of MAP treatment after low temperature storage for 49 days. And MAP+ESF treatment obviously increased the fruit firmness, decreased the flesh browning index, juice yield and total phenolic content and PPO activity. In addition, MAP+SF treatment delayed happening of fruit flesh browning, reduced the total phenol content, while increased the fruit juice rate and aggravated the fruit decay after 3 days shelf life in 20℃. MAP+ESF treatment retarded the fruit flesh browning and fruit decay, and reduced the juice rate and total phenol content. So the MAP+ESF treatment can effectively improve the fruit quality during storage and prolong shelf life.