Study On The Preservation Of Strawberry And Bayberry With Perforated Modified Atmosphere Packaging

Berry fruits are popular due to their rich nutrition,various antioxidant substances such as anthocyanins and phenols.Their high moisture content and lack of solid outer skin protection result in extremely short shelf life.At present,the commonly preservation techniques for fruits include low-temperature preservation,radiation preservation,ozone preservation,and modified atmosphere packaging preservation.However,these existing preservation technologies still cannot meet the preservation needs of berry fruits.Therefore,exploring more effective preservation techniques is of great significance for extending the shelf life of berry fruits.Strawberries and bayberries are more perishable varieties among berry fruits,and require higher preservation after harvest.Therefore,this article takes strawberries and bayberries as research objects,uses a combination of microporous film and modified atmosphere packaging technology for preservation treatment,explores the effects of single microporous preservation,microporous in combination with modified atmosphere packaging on the preservation of strawberries and bayberries after harvest,and establishes a multi quality shelf life prediction model,providing reference for the development and improvement of preservation techniques for perishable berry fruits.The specific research contents are as follows:1.Based on the conditions of hard box packaging,determine the MAP optimal atmosphere of strawberries and bayberries,use mathematical model to derive the microporous parameters that maintain the optimal atmosphere balance inside the packaging,and conduct experimental verification.To determine the MAP optimal atmosphere of strawberries and bayberries,different concentrations of gas composition（O₂/CO₂ concentration（%）:5/10,10/10,5/15）were used to treat the fruit.According to the closed system method,the respiration rates of strawberries and bayberries were measured,and parameter characterization was carried out based on the Michaelis-Menten.Combining the film thickness,area,permeability coefficient,and the optimal atmosphere,the micropore parameters were derived.Results showed that optimum atmosphere of bayberries was 10%O₂+10%CO₂+80%N₂ which could be maintained by using the perforated film（area 243.39 cm²）with 4 or 2 perforations of 100μm in pore diameter and it is consistent with the pore parameters derived using mathematical model.2.Based on the determined optimal atmosphere and microporous parameters for strawberries.Exploring the application of microporous modified atmosphere packaging in preservation of strawberries with 4 pores（100μm）.Strawberries were treated with MAP P4（10%O₂+10%CO₂+80%N₂with microporous film）and MAP P0（10%O₂+10%CO₂+80%N₂with no microporous film）.AIR P4（air with microporous film）was used as the control group,and the total phenols,anthocyanins,flavonoids and other physicochemical indicators of strawberries were measured during storage.Results showed that the preservation effect was MAP P4>MAP P0>AIR P4.MAP P4 increased the accumulation of polyphenolic compounds by maintaining the optimal atmosphere balance inside the packaging.At the end of storage,the total phenolic content increased by 25%,and the content of and anthocyanin and total flavonoid were 13%and 29%higher than the control group,respectively.At the same time,compared with the control group and MAP P0,MAP P4 significantly increased the activities of catalase,phenylalanine ammonia lyase,and ascorbic acid catalase.It was still marketable on the 19th day,extending the mold free shelf life of strawberries by 6 days at 4℃.3.Based on the determined optimal atmosphere and microporous parameters for bayberry.A study was conducted to evaluate the combined effect of gaseous ozone（OG）and perforated modified atmosphere packaging（MAP）on the preservation of bayberry.Different proportions of atmosphere and different concentrations of ozone were used to treat bayberry individually.Results showed that the optimal OG concentration was 18.3 mg/cm³according to the indicators such as decay rate,MDA etc.OG+MAP P2（18.3 mg/cm³ OG+10%O₂+10%CO₂+80%N₂with microporous film）and MAP P2（10%O₂+10%CO₂+80%N₂ with microporous film）were used to preserve the bayberry.The control group（CK）was the ordinary packaging without ozone treatment.Measure the decay rate,ascorbic acid catalase,phenylalanine ammonia lyase,and other indicators of bayberry during storage.Results showed that the preservation effect was OG+MAP P2>MAP P2>CK,indicating that OG or perforated MAP could inhibit the decay incidence and maintain higher content of total phenols,anthocyanins and total flavonoids in bayberry.Compound treatment enhanced the effect and effectively slowed down the decline of firmness,reducing losses of total soluble solids,titratable acid and ascorbic acid contents.Meanwhile,the peroxidase and superoxide dismutase activity were 1.42 and 1.9 times higher than those of untreated control,reducing the accumulation of H₂O₂ and O₂^-,thus extending the mold free shelf-life up to 8 days at 4℃.4.Based on the zero-order dynamic response model,establish a multi quality shelf-life model for strawberries and bayberries.Results showed that the R² of strawberry multi quality shelf models established with variables such as hardness,MDA,TSS,TA,anthocyanin,PAL and APX under different packaging was greater than 0.98,indicating a high correlation.Thus,it can effectively predict the changes in strawberry under different packaging during storage;At the same time,the R² of the shelf models for multiple quality indicators of bayberry under different preservation methods,with hardness,ASA,TSS,TA total phenol and flavonoid as variables,were all greater than 0.98,indicating a high correlation.Therefore,it can effectively predict the changes in bayberry quality under different preservation methods during storage.