Studies On Extraction Of Sweet Potato Dietary Fiber And Pectin

China has the largest sweet potato Production country which accounts for about 83% of the world sweet potato yield.Sweet potato residues are major by-product with a large amount form sweet potato processing, which have high moisture and pollute environment when discarded as waste. There are about 22% dietary fiber (DF) in dry sweet potato residues that can be used as good DF resource. In this paper, main composition of ten different sweet potato residues and their DF obtainted by sieving were evaluated, different smashing method and sieving times were considered to improve DF recovery rate, effective method of extracting pectin using Na2HPO4 at variable temperature, time and ratio of water to material was studied, and steamed bread adding sweet potato DF was made. The results were as follow:1. There were significant difference both in DF content of sweet potato residues and DF purity obtained by sieving. Comparing with the others, DF obtained from both Weiduoli and Xu 55-2 had higher DF purity and recovery rate, suggesting they were suitable for DF extraction.2. Compared with DF which obtainted after drying, smashing and sieving, smashed by colloid mill directly had high recovery rate of DF, which had higher purity and lower starch content. After twice sieving, recovery rate of all DF increased by almost one time than before, which did help for industrialization of sweet potato processing.3. The temperature, time, the ratio of water to material had significant effect on pectin extraction. The optimal technical conditions were obtained as follows: extracting temperature was 85℃,time was 6 hours and ratio of water to material was 1:100, and the extraction rate of pectin from sweet potato dietary fiber was 95.87%.4. Steamed bread adding proper quantity of sweet potato DF could improve quality of steamed bread. The best steamed bread was made when the flour mixed with 3% DF which had higher purity.DF were effective to promote steamed bread quality and to postpone steamed bread staling.With studying on sweet potato residues, sweet potato DF and sweet potato pectin, sweet potato variety that was suitable for extracting DF and an extraction method of gaining pectin were obtained, which were basis of further study on DF and pectin.