Effect Of Vacuum Impregnation Of Sugar Solution On Physiological And Biochemical Changes And Storage Quality Of Fresh-cut Yam

With the improvement of people's living standards and the pace of life is speeding up,fresh-cut fruits and vegetables are becoming more and more popular,because of the characteristics of fresh nutrition,clean and sanitary,convenient and quick.In this paper,the yam Tiegun,Bangchui,Foshou and Qingshuping were used as experimental materials to study the changes of color,browning degree,total phenolic content,free phenolic content and polyphenol oxidase activity during storage of fresh-cut yam.Then the yam variety for the follow-up experiments was determined,further the variety of sugar solution and its concentration were chosen,the effect of vacuum impregnation with sugar solution on physiological and biochemical changes and storage quality of fresh-cut yam were studied.The results were as follows:(1)The four kinds of fresh-cut yams(Tiegun,Bangchui,Foshou and Qingshuping)continuously decreased in L value during the storage period of 5o?,the a value,b value,browning degree,total phenol and free phenol content were rising,among them,the Bangchui yam had the biggest change,the Tiegun yam was the smallest,and the PPO activity showed a trend of increasing first and then decreasing.Correlation results showed that the browning degree of fresh-cut yam was positively correlated with a,b value,?E,total phenol content and free phenol content,and negatively correlated with L value(p<0.05).The browning degree of Bangchui and Qingshuping was significantly positively correlated with PPO activity(p<0.05),and the browning degree of Tiegun was not significantly correlated with PPO activity.The browning of yam was closely related to color,total phenol content,free phenol content and PPO activity.The fresh-cut Tiegun yam had a good color retention and high appearance quality,which was more suitable for fresh-cut processing.Therefore,in the subsequent experiments,the Tiegun yam was determined as the research object.(2)When stored at 5o?,the mass concentration of sorbitol,glucose,sucrose,maltose and trehalose with the smallest changes in quality of yam tablets after soaking were 7,8,12,13,and 8%,respectively.Relatively speaking,sucrose and maltose could be better maintained the apparent color of the fresh-cut Tiegun yam in the storage process,delaying the qualitydeterioration.Considering the way of obtaining,cost and practical feasibility,this experiment used 12% sucrose aqueous solution as the impregnation solution of fresh-cut Tiegun yam for vacuum impregnation research.(3)Vacuum impregnation of fresh-cut Tiegun yam could reduce the water loss rate,weight loss rate,respiratory intensity,malondialdehyde content,relative conductivity,delay hardness,ascorbic acid content,titratable acid content,ascorbic acid content,allantoin content of yam during 5o? storage period,and titratable acid content showed a very significant positive correlation(p<0.01).(4)The L value of the fresh-cut Tiegun yam vacuum-impregnated with sugar solution were decreased during 5o? storage period,the a value,b value,browning degree increased(p<0.05),and the higher vacuum degree,the greater the change was,having no positive effect on keep the colour and lustre of fresh-cut Tiegun yam.Even the higher the degree of vacuum,the deeper the degree of browning was,indicating that there was no colorprotecting effect on the fresh-cut yam.Correlation analysis showed that there was a significant positive correlation between browning degree and hardness,respiration intensity,malondialdehyde content,total phenolic content,PPO activity and POD activity.The browning of fresh-cut yam was closely related to these indicators.(5)The PPO activity,total phenolic content and flavonoid content of the fresh-cut Tiegun yam vacuum-impregnated with sugar solution were increased to some extent during5o? storage period,and the POD activity was decreased.Sensory evaluation showed that the-0.01 MPa sugar solution impregnation could delay the deterioration of fresh-cut yam and had a certain preservation effect.(6)The experimental results showed that during 5o? storage period,the vacuum impregnation of sugar solution had no obvious color protecting effect on the Tiegun yam,but it had certain protective effect on the nutrient composition,delayed the deterioration of tissue oxidation and reduced respiratory expenditure and water loss,had certain preservation effect,could maintain the value of the product to 12 d.