Study On The Regulation Of Preservation And Browning On Huangguan Pear By Microwave And Antioxidant Coatings

The test based on the microwave non-thermal effect principle,use the same low power microwave irradiation crested pear fruit for long time,control fruit temperature changes between 5±1?,the temperature is about 25?to eliminate heat effect.Test chooses DangShan Huangguan pear fruit,the output power of 32.5W,processing time2,3,4,5,and 6 min,put untreated as contrast.With slow cooling and rapid cooling way dispose fruit,stored at a relative humidity RH?90±2?%of the cold storage with0²?eventually,periodical sampling,study Huangguan pears'fruit respiration and ethylene release quantity,fruit quality and the influence of related elements on core browning with different methods of microwave processing time and cooling ways;Using primary and secondary microwave technology?32.5 W output power,processing time is 3,4,5,6,7 min,put untreated as contrast?and has the Phytic acid compound DSC dipped fruit processing,study the happening on fruit browning with slow cooling conditions during storage.To study the effect of low intensity microwave on the storage and preservation of Huangguan pear,provide theory and practice support for the Huangguan pear of microwave technology and innovative new ways of fruit dipped processing.The results of the study are as follows:1.The effects of different microwave treatments on the fruit temperature of Huangguan pear were studied.The longest treatment time on core and peel is 32.5W low power microwave that respective determined to be 6min and 7min,ensure that the fruit processing temperature at about 25?,the temperature difference between 5±1?.2.The changes of storage quality and fruit browning of Huangguan pear under different cooling methods were studied.The results showed that under the condition of slow cooling,the physiological and quality of the fruit were better.Control group and slowly cooled core browning final rapid cooling rate of 83.3%and 51.0%.3.The effects of different microwave treatments on the physiology and quality of Huangguan pear were studied.The results showed that the respiration intensity and ethylene release rate of the pear fruit were increased first and then decreased.There was a positive correlation between the respiration rate and ethylene release;slow cooling with 5min low power microwave treatment on the inhibition of respiration and ethylene release of Huangguan pear is best and the respiration and ethylene release were 26.93mgCO₂/kg·h?0.693ug/kg·h.The low intensity microwave treatment could also delay the decline of fruit hardness and VC content,the soluble solids content of maintaining high,prolong the storage period and storage quality of fruit.Fruit hardness,VC content and soluble solids content were controlled in6.19kg·cm^-2?3.23mg/100g?10.56%?4.The occurrence of heart browning in Huangguan pear was closely related to the total phenolics,polyphenol oxidase,malondialdehyde and oxygen free radical scavenging rate.The results showed that the total phenolics content increased first and then decreased during the storage process.The low energy microwave treatment had no obvious effect on the content of the total phenol,but delayed the decrease of total phenolic content,decreased the content of malondialdehyde rate and polyphenol oxidase activity.Among them,slow cooling combined with 32.5w/4min,32.5w/5min can be more obvious inhibition of fruit browning.The malondialdehyde,oxygen free radical scavenging rate and polyphenol oxidase activity were controlled at the end of storage by 2.022umol·g^-1?71.8%?6.113?OD460nm/?min·g??5.Different times of microwave treatment had different effects on fruit physiology and quality.The secondary microwave treatment had no significant difference in the change of the respiration intensity of the fruit,but had a significant effect on the hardness of the fruit and the decrease of the soluble solid.Storage for 180days,a treatment of 32.5w/6min,treatment of fruit hardness and soluble solids at one time was 6.16kg·cm^-2?11.47%.Secondary processing was 6.32kg·cm^-2?11.77%?6.There was significant difference between the first and second microwave treatments on browning of Huangguan pear.The results showed that the effect of secondary microwave on the content of total phenol was more obvious than that of the first microwave.The effect of secondary microwave on the inhibition of PPO activity,the increase of MDA content,the decrease of free radical scavenging rate and the increase of cell membrane permeability were significant.Simultaneously,the occurrence of peel browning was closely related to the content of?-fennesene and conjugated triene in the peel area.The content of?-fennesene increased rapidly in the early storage period,and then decreased gradually.The content of conjugated triene was rapid accumulation after 120 days storge,then the Huangguan pear peel browning increased incidence.Low power microwave treatment was not delay the onset of?-fenalene peak,reduced the amount of conjugated triene and peel browning index is low.The browning rate of the final fruit was 32%at 32.5w/6min,and the microwave at 32.5w/5min was 12%.The cell membrane permeability and the content of malondialdehyde were higher in the second microwave 7min treatment group,reached with 58.31%and 2.455umol·g^-1,the browning of the peel was serious.7.The combination of slow phytoplankton and phytic acid group was better able to ensure fruit quality,0.1%phytic acid complex 0.1%DSC dipping treatment group storage to 210 d.The had obvious control effect on hardness(5.953kg·cm^-2),TSS(5.953kg·cm^-2)and V_C content?2.286mg/100g?.The effect of phytic acid compound DSC and dipping group on the antioxidant activity of the peeled skin was significant,and the effect of 0.1%phytic acid compound 0.1%DSC was the best.phytic acid compound DSC solution on the antioxidant activity of the peeled skin was significant,and the effect of 0.1%phytic acid compound 0.15%DSC was the best.The browning rate of peel was 3.2%.