Research And Development On The Processing Technology Of Unicellular Purple Sweet Potato Mud And Its Chips

In this dissertation, the purple sweet potato variety of Nan-65supplied by Nanjing Agricultural Institute, Jiang su province was used as material, the conditions of purple sweet potato color protection process of fresh purple sweet potato slice and the process parameters of the single-cell purple sweet potato mud processing were investigated and optimized. The dispersion and the integrity of the cells in purple sweet potato mud were observed. Then, the single-cell purple sweet potato mud was mixed with mashed potatoes, rice flour and sugar, the purple sweet potato chips was developed by the pressure explosion puffing drying and microwave puffing. The main findings were summarized as follows:The effects of sodium bisulfite, citric acid and ascorbic acid on the color of purple sweet potato slices were observed and optimized using single factor and orthogonal factor design method, the results showed that the order of the purple sweet potato color protection of these color protecting agents from the best to worse was sodium bisulfite> citric acid> ascorbic acid. The optimimum color protection conditions was0.05%of sodium bisulfite,0.06%of ascorbic acid,0.16%of citric acid, soaking for10min.The effects of blanching time, blanching temperature, cooking time, calcium concentration, emulsifier concentration, and slice thickness on the the integrity of the cells in purple sweet potato mud were observed and optimized using orthogonal factor design method, the results showed that the optimum processing conditions of low cell disruption purple sweet potato mud were:blanching temperature70℃for10min, and cooking for9min at the temperature of100℃. Under these conditions, it has found that the free starch content in purple sweet potato mud was5.75%.The dispersion and the integrity of the cells in purple sweet potato mud were observed with scanning electron microscopy. The effects of pectin pulp enzyme and the ultrasonic treatments on the quality of purple sweet potato mud were analyed and compared.The results showed that the dispersion of the cells in purple sweet potato mud treated by pectin pulp enzyme was better than that by ultrasound treatment, but in terms of the integrity of cells, the former worse than the latter. Thereby, it was much better to select the pectin pulp enzymatic treatment to prepare single-celled purple sweet potato mud from comprehensive consideration.The quality changeof fresh purple sweet potato slices and purple sweet potato mud at-18℃was investigated, it has found that the rate of cell disruption has increased after45days while the Anthocyanins content and the total phenol index reduced over time.Forthmore, the glutinous rice flavor puffed purple potato chips was developed, the taste and hardness of the purple potato chips processed by explosion puffing drying and microwave puffing were assessed. The results showed that the microwave puffing was better than explosion puffing drying in aspect of the expansion ratio and the sense of crisp, but its uniformity of heating was worse than microwave puffing. The best formula of purple sweet potato chips was:the proportion of mashed potatoes to purple mashed potatoes was60:40,10%of glutinous rice flour,8%of sugar,0.2%of salt and0.2%of leavening agent. After fuzzy evaluation the product could come to "prefer" level.