Research On Preservation Technology Of Blueberry

The characteristics of blueberry are full of nutriments,bright colour and luster,convenience edible,etc,and it is favored by consumers.However,the organization structure of blueberry fresh fruit after picking and packaging is damaged,and which results in the following issues,such as the brown stain of organization,infection of microorganism,nutrient loss,etc.So the shelf life of blueberry fresh fruit is cut down,and the listed value is reduced,the studying on preservation technology of blueberry appears to be particularly important.Chitosan is the natural macromolecular biodegradable material,and a suitable concentration of chitosan solution is used to coat the surface of fruits and vegetables,the respiration of the skin pores can be prevented and the evaporation of water in the fruit can be inhibited by the formed chitosan protective film.Ozone which is non-toxic and pollution-free is the strong oxidant,and the most of the bacteria,fungi and viruses in the surface and storage space of fruits and vegetables can be killed.In this paper,three methods including coating of chitosan,ozone fumigation and compound preservation methods are adopted to study the preservation effects of blueberries in different storage temperatures(4℃、0℃、-4℃).The main research contents are as follows.(1)Using different concentration of chitosan solution to film the blueberry fruits which are stored in 45 days,and the quality change of blueberries is measured under the storage conditions of 4℃,0℃,and 4℃.The related indicators including soluble solids,titratable acid,ascorbic acid,malondialdehyde,anthocyanin,and healthy fruit rate are measured during the storage of blueberry.The best chitosan coating method is screened out for blueberry preservation.(2)The fruits of blueberry which are stored in 45 days were treated with ozone gas in different time by ozonator(ozone output 33.3 mg/min),and the quality change of blueberries is measured under the storage conditions of 4℃,0℃,and 4℃.The best ozone fumigation preservation method for blueberries is screened out.(3)The compound preservation technique including first coating and gas fume is adopted to maintain the fresh of blueberry fruits,and the fruits are stored in 45 days.The change of related indicators is studied,and the optimal treatment method of composite preservation is screened out.Comparing and analyzing the test results,the conclusions are showed as follows.(1)In experiment of chitosan coating preservation,using the 1.5% concentration of chitosan treatment,the soluble solids,titratable acid and ascorbic acid can be stable,and the content of malondialdehyde is lower,the decline of content of anthocyanin is slowed down under 0℃.(2)In experiment of ozone gas fume preservation,the effect of ozone preservation is best in 25 min treatment time under 0℃ storage conditions,and the blueberry quality is better than which under-4℃ and 4℃ storage conditions.The decline of anthocyanin content and soluble solids content of blueberry fruit is slowed down in longtime ozone gas fume,the blueberry appearance is maintained,and the healthy fruit rate is improved.(3)In experiment of compound preservation,on 45 day,the healthy fruit rate is higher than that of the other two preservation methods obviously.The healthy fruit rate with strorage treatment(2.5%～15min)under 0℃ storage condition is 90%,the content of anthocyanin is higher than that under-4℃ and 0℃ storage condition,and the content of malondialdehyde is lower than that under-4℃ and 0℃ storage condition,it is shown that the preservation effect is best.In conclusion,under 0℃ storage condition,the compound fresh-keeping method(2.5%chitosan concentration,15 min ozone ventilation time)is the best,and the next is chitosan coating treatment(1.5% chitosan concentration),the last is ozone treatment(25 min ozone ventilation time).The compound preservation method is better than the other methods,and the healthy fruit rate can reach on 92.16%.In three different tempreatures,the preservation effect under 0℃ storage condition is better than that under-4℃ and 4℃ storage conditions.The three fresh-keeping methods play a different degree of fresh preservation effect,and the preservation effect of compound processing is better than chitosan and ozone.In conclusion,the compound preservation method can effectively improve the blueberry healthy fruit rates,and delay the decomposition of soluble sugar and organic acid,reduce the content of malondialdehyde,stable the content of anthocyanins,prolong the storage period of blueberry and improve its edible and commodity value.