Study On The Effect In The Postharvest Quality And Mechanism Of Several Fruits And Vegetables In High-Voltage Electrostatic Field

Since Murr discovered that simulated electric field could affect the growth of orchard grass in 1963, the research on the effect on bio-effective in high voltage electrostatic field (HVEF) is quiet active for nearly 40 years, such as improving seed germination, affecting the growth of plants, affecting post-harvest qualities of fruits and so on. Some research results showed that post-harvest qualities of tomato, cucumber and cowpea had been affected in HVEF. However, whether the influence on post-harvest quality of other fruits in HVEF has a general principle or not, as well as its mechanism has not been clear yet.'Dongzao', 'Ya' pear, strawberry, tomato and apple have been investigated in -50kV/m and -100kV/m HVEF produced by the self-made storage device. Some indexes of post-harvest qualities have been measured during storage such as the content amount change of endogenous polyamine, activity of polygalacturonase and carboxymethylcellulase, black heart rate of 'Ya' pear, rot rate of strawberry, fruit firmness, soluble solids content and the change of freezing point. At the late period of storage, sensory evaluation of qualities of fruits was measured. Experimental results in HVEF show that:1. They have a different effect on the content amount change of endogenous polyamine of'Ya' pear, tomato and strawberry in HVEF. HVEF treatment has a little effect on the content of endogenous polyamine of 'Ya' pear and tomato at the early period of storage, except the content amount of endogenous putrescine of 'Ya' pear, others content amount of endogenous polyamine are lower than the control at the later of storage. During the 12 days storage of strawberry, except the sixth, the content amount of putrescine of the control are always kept in a higher level. However, during the late period of storage, the spermidine content in HEVF was significantly higher than the control. When stored for 6 days in -lOOkV/m HVEF, the spermidine content was 1.76 times than that of the control. The spermine content in HEW had not a significant difference with the control.2. The activity of polygalacturonase and carboxymethylcellulase of tomato and strawberry is restrained in HVEF, and therefore the soften of tomato and strawberry are restrained.3. ' Ya' pear black heart rate in HEVF is obviously lower than the control when stored for 240 days.4. Strawberry rot rate in HEVF is obviously lower than the control when stored for 12 days.5. Sensory evaluation results showed that the main sensory indexes such as fruits fresh degree, firmness and sweetness are better than the control when 'Dongzao' stored for 84 days, strawberry stored 12 days, Gold delicious apple stored 24 days and Red delicious apple stored 24 days in HVEF.6. The experiment results also proved that short HVEF treatment had no effect on fruit freezing point.7. HEVF has a significant effect on keeping fruit soluble solids content, and on restraining the color change of gold delicious apple and tomato. The maturation and senescence speed of 'Dongzao', 'Ya' pear, strawberry and apple are obviously restrained in HEVF, and it can play a better role on keeping the post-harvest qualities of fruits in HVEF.