Study On Processing Technology Of New Functional Food With Purple Potatoes

Purple potatoes, not only have abundant nutritional components but also are rich in bioactive components such as anthocyanin and polyphenol. According to researches published, the anthocyanin which exists in purple potatoes shows diversified functions, such as anticancer, hepatoprotective activity, antivirus, anti-aging and prophylactic functions. Purple potatoes originated from South America and have been introduced into China in recent years. They were planted in many regions in China, Gansu, Yunnan and Zhejiang province for example. In order to make full use of this resource in China and make further progress in the utilization ratio and added-value of purple potatoes, two kinds of novel products—purple potato beverage and purple potato and rice wine—which embrace both nutritional and health care functions were exploited.The optimum technological parameters for enzymatic extraction, the optimal formula of purple potato beverage and the appropriate type and dosage of stabilizer were determined through orthogonal tests coupled with single factor experiments. It turned out that the optimum technological parameters for enzymatic extraction would be:the dosage of amylase and pectinase were 0.03% and 0.05%,the temperature and the time for hydrolysis were 50℃and 3h,respectively. The formula which guarantees the beverage with both excellent flavor and visual color was 300mL/L of purple potato juice,2g/L citric acid,120g/L sugar and 9g/L honey.Finally,0.1% xanthan was added to the beverage to keep it stable and pellucide.Two different methods of producing purple potato and rice wine were studied. One was Tanfan method which cools the steamed rice with natural air and all the material was put into the beaker one by one at a time. The optimal formative parameters were as follows:the weight ratio of purple potato to rice was 1:10, the temperature and time for fermentation were 26℃and 54h respectively and the weight ration of material to wine yeast was 0.6%, which were determined through orthogonal tests and sensory evaluation. However, the other was combined Linfan method with Weifan method, which put all materials into the beaker in three steps. Firstly the steamed rice and koji was put into the beaker. After mixed round, a hole was made at the middle of the mixture. Secondly, purple potato was added into the beaker after some time. Finally, wheat cojic and water were added into the beaker. According to the results of orthogonal tests and single factor tests, the optimum parameters for fermentation were as follows:the weight ratio of koji to rice was 0.4%, the fermentation temperature was 28℃,the weight ratio of rice and purple potato to wheat cojic was 13% and that of rice and purple to water was 1:0.8.Comparing the two methods, the latter was more complicated and requires more time than the former, nevertheless, taking the final product into consideration, the latter produced higher level quality wine than the former, not only in terms of taste and color, but also in terms of nutritional functions.