Study On Process Optimization Of Sweet Potato Juice Concentrate And Carbohydrate Analysis

Sweet potato (Ipomoea. batatas LAM.), with rich nutrition and special health function, is an important crop, feed and industrial raw materials in the world. Sweet potato juice concentrate, as one of sweet potato productions, is popular with the consumers in Europe with huge market potential. China is the biggest sweet potato production country, the production of which is about 77.51% of the volume of the world. However, sweet potato juice concentrate industry is still in its infancy in China, and the technology is defective. Therefore, the study on the process of sweet potato juice concentrate is essential in promoting the development of international trade of sweet potato juice in China.This paper optimizes the best sweet potato variety, which is suit for processing into sweet potato juice concentrate, and study on the process of juicing, liquefaction, saccharification, clarification, and the process parameters model was built by using Response Surface Method (RSM). Meanwhile, monosaccharides, disaccharides of the important process were also researched using HPLC. The main test results are as follows:1. Comparing the starch content, moisture content, juice yield and reducing sugar content between QinShu No.5 and XiNong 431, XiNong 431 is more suitable for sweet potato juice concentrate processing.2. According to study of single factor (α-amylase addition,temperature and treatment time) in pressing juice, the results indicated that the optimal process parameters areα-amylase addition of 40U/g, temperature 95°c, treatment time 2.5h.3. Response surface methodology was successfully applied for optimization of the enzymatic hydrolysis of Glucoamylase to sweet potato juice. The high regression coefficients of second-order polynomial of the response showed that models fitted data well. And the descending order impact of the ultrasonic removal conditions was pectinase addition >Time> temperature. The maximum content of soluble reducing sugar in sweet potato juice concentrate in theory will be reached to 7.05%when Glucoamylase addition 424.142U/g, the treatment time 4.123h and the treatment temperature 58.31℃at pH 5. and actually maximum content of soluble reducing sugar in sweet potato juice will be reached to 6.84%. 4. Response surface methodology was successfully applied for optimization of the clarification of sweet potato juice by pectinase. The high regression coefficients of second-order polynomial of the response showed that models fitted data well. And the descending order impact of the ultrasonic removal conditions was temperature>Time> pectinase addition. The maximum light transmission rate in theory will be reached to 86.86% when pectinase addition 184.296U/g, the treatment time 2.633h and the treatment temperature 29.944℃at pH 4. And actually maximum content of soluble reducing sugar in sweet potato juice will be reached to 87.92%.5. There is highest maltose content after liquefaction, highest glucose content after saccharification, and Glucose levels continue to rise after clarification. Fructose content increases from 0.40mg/mL to 5.41mg/mL after clarification treated by pectinase. The contents of Glucose, fructose, sucrose and maltose is stable between the product which is treated by vacuum concentration and the final product.6. The product of sweet potato juice has a reddish brown color. It tasted sweet, and is full-bodied sweet potato flavor. After storing in the refrigerator for 30 days, there is no turbidity in the sweet potato juice concentrate.