Effects Of Space Electrostatic Field Combined With Low Temperature Storage On Fruit Quality Of Bayberry

In this study,the fruits of the two main bayberry varieties‘Dongkui’and‘Biqi’were used as the test materials to study the effect of space electric field treatment on the storage and preservation of fruits.The space electric field is a safe electrostatic field with a heteropolar distance of about 2.5 cm,which can be entered by both humans and living beings.This study analyzed the effects of space electric field combined with low-temperature storage on the fruit quality of bayberry fruit,including fruit color,organic acid,soluble sugar and aroma,and provided a theoretical basis for the research and development of new fresh-keeping technologies for perishable and difficult-to-storage fruits such as bayberry.The main results are as follows:1.The study showed that compared with the conventional low temperature storage（control group）,the effect of space electric field combined with low temperature storage on the weight loss rate of bayberry fruit was more significant.After storage for 20-30days,the weight loss rate of‘Dongkui’fruit was 8%lower than that of the control.The space electric field could effectively delay the reduction of firmness,and the fruit softening rate in the control group was 18.73%-29.7%higher than that in the treatment group.The appearance quality of fruits during storage was also significantly improved.After 20 d of storage,space electric field treatment significantly improved fruit coloration and delayed the decline of soluble solids content.The soluble sugar of bayberry was mainly composed of sucrose,fructose and glucose.The sucrose content of bayberry fruit after 20 days of space electric field treatment was higher than that of the control group,and the content of two main organic acids such as citric acid and malic acid was lower than that of the control group.2.During the storage period,the activity of acid invertase in‘Dongkui’and‘Biqi’fruits showed an overall upward trend,and the enzyme activity of the treatment group was higher than that of the control group.The neutral invertase activity of‘Dongkui’showed an upward trend,reaching the highest value of 0.47μmol·h^-1·g^-1·FW on the20th day,which was 1.4 times that of the control group.There was a downward trend,but the enzymatic activities of the treated groups were higher than those of the control group.The activities of sucrose synthase（synthesis direction and decomposition direction）in the fruit of the treatment group were also higher than those of the control group.The sucrose phosphate synthase activity showed a downward trend during the whole storage period,and the enzyme activity of the fruit in the treatment group was about 3 times that of the control group after 20 days of storage.It showed that the activity of sucrose metabolizing enzymes in bayberry fruit was significantly enhanced after the treatment of space electric field.3.Aroma is one of the key indicators for evaluating fruit flavor.In this study,185aroma compounds were identified in the bayberry fruit,mainly including aldehydes,alcohols,terpenes,esters and ketones.Terpenoids,as the characteristic aroma substances of bayberry fruit,account for more than 90%of the total aroma substances.β-Caryophyllene is the most abundant aroma substance in bayberry fruit.During storage,the content ofβ-caryophyllene in‘Dongkui’bayberry fruit showed an upward trend,and the content of the treatment group was 2.25 times higher than that of the control group at the later stage of storage.In addition,the space electric field treatment favored the accumulation of hexanal,nonanal,decanal,linalool,α-caryophyllene,β-caryophyllene,β-ocimene,α-farnesene,and isocaryophillene,reducing the contents of1-octanol,D-limonene,andα-pinene.4.The sensory evaluation analysis of bayberry fruit showed that the flavor of the fruit was significantly different after 20 days of storage in the space electric field,and the fruit score of the treatment group was better than that of the control group.The difference was the largest at 30 days of storage.The overall preference score of the treatment group was 15 points higher than that of the control group,of which the aroma score was 22 points,20 points higher than the control group,32 points for sweetness,13 points higher than the control group,and 30 points for acidity,9 points higher than the control group.It shows that consumers are more inclined to the processed bayberry fruit,and the space electric field treatment can maintain the flavor quality of the fruit.5.The combination of space electric field and low temperature storage can prolong the fresh-keeping period of bayberry fruit to 50 days,while the fruit stored at low temperature（without applying electric field）for 30 days has completely rotted.After conventional low temperature storage of‘Dongkui’bayberry fruit for 30 days and‘Biqi’for 25 days,the fruit has completely lost its commercial value.However,the fruit stored by using the space electric field still has commercial value for 50 days.The average price of bayberry is 78.9 RMB/kg,which is more than twice the price at the time of picking.