Study On The Quality Of Mango During Drying And Storage Stability Of Dried Mango Slices

As one of climacteric fruits,mango is prone to decay,deterioration and cold damage,which leads to a great economic loss.Currently,problems such as high energy consumption,low effiency,high cost are caused by traditional producing technique-hot air drying.High sugar content,residual sulfur dioxide,sugar melting and crystallization,deteriation during storage of dried mango slices are also increasingly concerned by the public.As a result,in this article,mango(Sensation)was chosen as the main raw material to study the effect of pretreatment,osmotic dehydration and ultrasonic-assisted pretreatment combined with far infrared drying(FIRD)and hot air drying(HAD)on mango.In addition,effects of packaging,storage temperature and time on storage stability of dried mango slices was determined,so as to explore a high efficient drying and storing technique,improve the quality and the economic value of dried mango slices,and provide theoretical reference for promoting the development of processing industry of dried mango slices.The main research contents and conclusions of this article are as follows:1.Drying temperature had a significant effect on mango showing that when the temperature was more than 60°C,it caused browning,shrinkage to mango;when the temperature was less than 60°C,it also caused slight browing.Therefore,the optimal drying temperature of mango was determined to be 60°C.2.Pretreatment combined with hot air drying and far infrared drying was used to solve problems,such as residual sulfur dioxide and deteriation during storage of dried mango slices.Pretreatment(0.1% citric acid + 0.5% ascorbic acid + 0.5% calcium chloride + 1% sodium chloride soaking for 1 h)retarding the browning of mango and preventing residual sulfur dioxide in dried mango slices,was a desirable alternative to traditional sulfur dioxide method for color protection.It combined with drying can significantly increase the content of reducing sugar,ascorbic acid,and total phenol and phenolic acid,and better maintain the color of dried mango slices.Ultrasound-assisted pretreatment can improve the brightness of mango and increase the content of its reducing sugar without significant effect on other quality indexes of mango.Although drying seriously damaged the microstructure of mango,pretreatment combined with far-infrared drying could retain more pores and lower the hardness of the dried mango slices to some extent.3.The citric acid was used to avoid sugar melting and crystallization of dried mango slices.The optimal osmotic conditions: mango immersed in 35%(w/w)sucrose solution with 0.13% ~ 0.14% citric acid added under the solid-liquid ratio 1:4 for 40 h.There is no sugar melting and crystallization on mango slices dried by FIRD and HAD.Those dried by FIRD maintained better color with lower hardness,and gained 87 points which was higher than that of samples dried by HAD(83 points)4.Modified atmosphere packaging was used to improve the quality of dried mango slices during storage.The physio-chemical indicators and nutrients of dried mango slices changed significantly during storage.Higher the storage temperature,deeper the browning degree of the dried mango slices in all packages,and lower the retention rate of ascorbic acid and ?-carotene was observed.It is suitable for dried mango slices to store at 25°C,where nutrients and color were relatively stable.After 6-month storage,the retention of ascorbic acid(38.80% ~ 61.21%)and ?-carotene(50.99% ~ 66.99%)of dried mango slices packed with modified atmospheres were higher than that of ascorbic acid(29.94%)and ?-carotene(45.71%)of samples under airpacked,respectively.By the end of storage at 37°C and 50°C,the retention of ascorbic acid suddenly decreased to 9.43% ~ 12.82% and 5.55% ~ 8.45%,respectively,and there was no significant difference between samples in all packages.Similarly,the ?-carotene content of dried mango slices decreased significantly during storage,with 37.83% ~ 63.12% retention of samples at 37°C and 33.00% ~ 47.73% retention at 50°C,respectively.Modified atmosphere packaging retained higher ?-carotene content than air-packaging.Generally speaking,storing at 25°C combined with modified atmosphere packaging can significantly delay the quality deterioration of dried mango slices.