Research On Composite Storage And Preservation Technology Of 'Tunisia' Soft-seeded Pomegranate

Soft seed pomegranate has been introduced into China since 1986,with an area of about 200,000 mu and an annual total output of nearly 300,000 tons.This variety of pomegranate seeds are soft edible,sweet and sour palatable,have bright color,deeply liked by consumers.However,problems such as browning of pericarp,deterioration of grain and softening and decaying of fruit are easy to occur in the process of fruit storage,which seriously affects the commercial value of fruit after storage.In this paper,the effects of storage temperature and treatment with 1-methylcyclopropylene(1-MCP)on postharment physiological characteristics and fruit quality of soft seed pomegranates were studied by taking Tunis' pomegranates from tongguan,shaanxi province as test materials.The pathogen of fruit rot disease during storage was analyzed and identified,and the control effect of different bacteriostatic agents on the disease was investigated.The response surface method was used to optimize the optimal parameters of storage and preservation technology of soft seed pomegranate.The main research results are as follows:1.Soft seed pomegranate is not good at storage resistance,at normal temperature for 20 days,it will rot or dry shrinkage,loss of commercial value.The changes of respiration physiology,decaying weightlessness and grain quality of soft seed pomegranate were different under different storage temperatures.The study found that storage at(3±0.5)? could inhibit soft seeds pomegranate peel polyphenol oxidase(PPO)and peroxidase(POD)activity increased,reduce soluble solids,titratable acid and cut down the content of reducing sugar and slows the pericarp browning index and physiological metabolism,prevent fruit softening decay,extend the storage period,keep the soft seeds pomegranate quality and good flavor.2.The 1-MCP treatment has a better preservation effect on pomegranate with soft seeds.The 1.0 mg/L 1-MCP treatment can effectively maintain the nutritional components of pomegranate seeds,slow down the physiological metabolism,prevent the browns of the fruit skins,reduce the decay and loss,and extend the storage period.After storage,the fruit has a bright appearance,full seeds inside,and a high commercial fruit rate.Compared with the control group,the differences of indexes were significant.3.By means of colony morphology analysis and ITS sequence determination,the microorganisms growing on the fruit surface during storage of 'Tunis' soft seed pomegranate were identified as Rhizopus oryzae,penicillium crustosum,Aspergillus Niger and Enterobacter asburiae.It was found that Rhizopus oryzae,penicillium oryzae and aspergillus Niger could cause the fruit decay,and the disease symptoms were basically the same as those of the tested fruit.Therefore,the three bacteria were the pathogenic bacteria of soft seed pomegranate.4.Treatment with natamycin and chitosan oligosaccharide at different concentrations could inhibit the growth of penicillium and aspergillus niger,natamycin could inhibit Rhizopus oryzae while chitosan oligosaccharides could not control Rhizopus oryzae.Treatment with 0.05%natamycin solution can maintain the content of reducing sugar,titratable acid and soluble solids in pomegranate seeds,delay the browning of fruits,reduce the respiratory intensity of fruits,and effectively prevent the occurrence of diseases during fruit storage.5.The optimal parameters of the composite storage and preservation technology of Tunis' soft seed pomegranate were obtained by response surface test optimization;storage temperature(2±0.5)?,natamycin concentration of 0.07%,1-MCP concentration of 1.0 mg/L.Under the condition of storage of pomegranate 120 d,the nutritional composition of the fruit is good,the taste and flavor of the seeds are good,and the fresh-keeping effect is ideal.