Effects Of Different Harvesting Periods On Core Browning During Storage Of Whangkeumbae Pears And Development Of Anti-browning Technology

Pyrus pyrifoli Nakai cv.Whangkeumbae are excellent pear varieties that have been developed in the last three or four decades and are widely cultivated in many provinces in China.It has strong respiratory metabolism after harvesting,and it is prone to browning of fruit during low temperature and storage at room temperature,resulting in a decline in its commercial value and huge economic losses.The study found that timely harvesting can alleviate the core browning of Whangkeumbae pear.Therefore,it is of great significance to study the effects of different harvesting periods on the core browning of Whangkeumbae pear and the development of anti-brown technology.In this experiment,Whangkeumbae pear was used as the experimental material to study the effects of different harvesting periods on the core browning of Whangkeumbae pear during low temperature storage.At the same time,the effect of hexanal treatment on the core browning of Whangkeumbae pear during room temperature storage was studied.Finally,the effects of different harvesting periods on the occurrence of core browning during storage of Whangkeumbae pears were described from three aspects:ros metabolism,membrane lipid metabolism and energy metabolism.A hexanal treatment was developed to delay the core browning during storage at room temperature.The technique of browning occurs and briefly explores its potential anti-browning mechanism from the perspective of membrane lipid metabolism.The results are as follows:?1?The effects of different harvesting periods on the occurrence of browning and the metabolism of reactive oxygen species in Whangkeumbae pears under low temperature storage were studied.The results showed that proper early harvesting can delay the decrease of hardness and titratable acid content of Whangkeumbae pear during storage,inhibiting malondialdehyde?MDA?,membrane ion permeability,O₂^·-production rate,H₂O₂content,total phenol content and?PPO?activity.The increase,maintaining relatively high activity of Superoxide Dismutase?SOD?,Catalase?CAT?and Peroxidase?POD?inhibited the core browning of Whangkeumbae pear fruit.The occurrence of browning of Whangkeumbae pear fruit is closely related to the level of lipid peroxidation in the pericardium.The harvesting period can affect the membrane lipid peroxidation level and the occurrence time and incidence of browning in the fruit during storage,and timely harvesting can be better.Inhibition of the Whangkeumbae pears,the consequences of core browning.?2?The effects of different harvesting periods on membrane lipid metabolism and energy metabolism during the core browning of Whangkeumbae pear fruit were studied.The results showed that compared with early harvesting,the late harvested Whangkeumbae pear fruit had higher phospholipase D?PLD?,lipoxygenase?LOX?activity and lipase?LPS?activity;the late harvested Whangkeumbae pear had lower content of unsaturated fatty acids.Membrane lipid unsaturation index and fatty acid unsaturation are lower than early fruit picking;late harvest affects the stability of cell membrane during storage,leading to the early occurrence of fruit browning.From the perspective of energy metabolism,late harvesting fruits have lower ATP content and energy load value,which is easy to cause energy deficit during low temperature storage,which leads to browning of fruit heart;in addition,H⁺-ATPase in late harvest fruits,Ca²⁺-ATPase and Mg²⁺-ATPase activities are also at relatively low levels,which may be detrimental to maintaining intracellular homeostasis and leading to browning.?3?The effect of hexaldehyde treatment on the core browning of the Whangkeumbae pear during storage at room temperature was studied.The results showed that hexaldehyde was a phospholipase D inhibitor,and the respiration intensity and ethylene release rate of hexaldehyde fumigated Whangkeumbae pear were lower than CK,which delayed the decline of storage quality of Whangkeumbae pear.At the same time,hexaldehyde treatment also significantly inhibited the activity of key enzyme in the membrane lipid metabolism of the fruit heart,increased the membrane lipid unsaturated index and fatty acid unsaturation,and delayed the Browning of the fruit heart of the golden pear.