Studies On Preparation Of Dietary Fiber From Sweet Potato And Its Efficacy On Ulcerative Colitis

Introduction:Ulcerative colitis,which is short of UC, is a kind of inflammatory bowel disease incidence in colon mucosa and submucosa, reported in 1875 firstly. In recent decades,the incidence of UC is increasing year by year.UC has been listed as a kind of disease which is difficult to cure in modern society just for its complex etiology, delayed healing,recurrent.Clinically, there is not effective medicine that can cure it.Some ancient books about traditional Chinese medicine said that sweet potato can be used to prevent and treat UC.However,that sweet potato was used to prevent and treat UC has been reported rarely in real-life.With the deepening study for UC, a certain relationship between UC and intake of dietary fiber(DF) was explored. Meanwhile, some literature also confirmed DF had a positive effect for UC. Studies showed that sweet potato was rich in DF. But that whether DF was the material basis of sweet potato for preventing UC and studies about using DF from sweet potato to prevent and treat UC had not been reported systematically.So the suitable variety of sweet potato for preparing DF was screened and the optimal technology of preparing DF from sweet potato with the combined technology of enzymolysis with alkaline hydrolysis was determined by single factor and orthogonal tests in this study. Besides, the quality of DF products was identified and the preventive and therapeutic effect of DF from sweet potato for UC was explored initially.Objective:The combined technology of enzymolysis with alkaline hydrolysis was used to prepare dietary fiber from sweet potato and single factor and orthogonal array design experiments were carried out to optimize the preparation procedure.Besides,composition and physical and chemical properties of DF product were determined and analyzed,objectives of this research were not only to provide experimental basis for integrated application of sweet potato and industrial development of dietary fiber from sweet potato,but also to provide experimental reference for the quality-identification of dietary fiber product. In addition, that the efficacy study of dietary fiber from sweet potato on ulcerative colitis is aiming at providing experimental basis and new ideas of prevention and treatment for ulcerative colitis.Methods:1. Studies on preparative process of dietary fiber from sweet potato: enzymolysis and alkaline hydrolysis were combined masterly to prepare DF from sweet potato,the yield of DF and content of SDF were used as indicators to filter suitable varieties of sweet potato. On this basis.Effect of the eight factors on the yield of DF was tested respectively by the single factor experiment,those refers to the ratio of material to liquid, the dosage of lipase, the ratio and dosage of mixed enzyme(medium temperature α-amylase and glucoamylase), the dosage of papain and p H,temperature and time of alkaline hydrolysis. The orthogonal test of enzyme dosage and the orthogonal test of alkaline hydrolysis were carried out in order to define the suitable variety of sweet potato and the optimum preparative process ultimately.2. Determination of composition and physicochemical properties of DF from sweet potato: the methods from national food safety standard were used to determine and analyze the content of main ingredients in DF products.The physicochemical properties(water holding capacity, oil holding capacity, expansion,etc) and the functional properties(the adsorption capacity for glucose, heavy metals, nitrite and the exchange capacity for cation) were determined respectively.3. Studies on efficacy of DF from sweet potato on UC: the preventive and therapeutic effects of DF from sweet potato on UC was explored through the preventive and therapeutic experiment, normal control group, model group,sweet potato powder group and DF group were set in the preventive experiment.Before modeling,sweet potato powder group and DF group were given a gavage of suspension of sweet potato powder and DF respectively, meanwhile, normal group and model group were delivered by the same capacity of normal saline gavage for 1 week. Then UC rat model was constructed by using dextran sulfate sodium(DSS) in the other groups except normal group, while,all groups were given the same intervention as that before modeling, finally the preventive effect of DF was evaluated through general condition observation of rats,colon morphological observation and serum MPO determination in each group. Positive control group was added in the therapeutic experiment compared to the preventive experiment, rats in every group were treated correspondingly after modeling. the therapeutic effect of DF was also evaluated by general condition observation, colon morphological observation, colon pathological observation and determination of blood index( Dao and D-lactate in plasma, MPO and TNF-α in serum).4. Preparation and quality examination to tablets of DF from sweet potato: Tablets were made with raw material(DF from sweet potato) and suitable auxiliary material(fillers,flavoring agents, adhesive, etc) by the method of wet granulation tabletting. Then quality examination to tablets of DF was made according to provisions of the State Pharmacopoeia for tablets.Results:1. Studies on preparative process of dietary fiber from sweet potato: Screening results of varieties of sweet potato showed that the comprehensive evaluation value of yellow heart sweet potato was 52.61%,higher than that of purple heart sweet potato, red heart sweet potato and white heart sweet potato, which was 45.51%, 45.96% and 51.71% respectively.Hence, yellow heart sweet potato was the best candidate for preparing DF. Optimal preparation technology within the experimental range was determined by single factor and orthogonal tests,that was as follow: the ratio of material to liquid was 1:10; the proportion of lipase, mixed enzyme(medium temperature α-amylase: glucoamylase =4:6 or 2:3) and papain to substrate was 0.5%, 0.6% and 0.2% respectively;p H,temperature and time of alkaline hydrolysis was 8.5, 60℃ and 1.5 h. In this process,the average yield of DF was up to 69.12%.2. Determination of composition and physicochemical properties of DF from sweet potato:the content of DF in soluble and insoluble products were 83.74% and 73.52%,both of which were increased compared with that of sweet potato, namely 24.21%.Results suggest that the purification process reduced the content of other impurities and improved the purity of DF products effectively. Water holding capacity, oil holding capacity, expansion, emulsifying activity and emulsion stability of DF products were9.33 g / g, 3.96 g / g, 6.23 ml / g, 55.06% and 64.24%; Results of functional properties showed further that DF from sweet potato possessed a strong adsorption capacity for glucose, heavy metals and nitrite as well as a strong cation exchange capacity.3. Studies on efficacy of DF from sweet potato for ulcerative colitis : results of the preventive experiment showed that the weight of rats in normal group increased while the other three group decreased to varying degrees during molding; The serum MPO level of rats in model group was higher significantly that in normal group, DF group and sweet potato powder group at the end of molding; The results of gross colon morphology showed that large-area dispersion of peptic ulcer could be observed in model group while colonic lesions were relatively mild in DF group and sweet potato powder group; The gross morphological score of colon in DF group was significantly lower than that in model group; However, the gross morphological score of colon in sweet potato had no significant difference with model group; Besides, the thickness of colon in model group was lower than that in the other three groups. Results of The therapeutic experiment showed that DAI score in positive control group decreased more rapidly and obviously than DF group and sweet potato powder group; However, compared with model group,DAI score significantly decreased in DF group and sweet potato powder group; The weight of 10 cm colon in model group was significantly lower than that in normal group,positive control group and DF group; The results of pathological section showed that large-area colonic mucosa injury and inflammatory cell infiltration were observed,Epithelial cells and goblet cells widely dissolved in model group. But the above symptoms had improved in the other group; Compared with normal group, the level of plasma DAO and D-lactic acid significantly increased in model group( p<0.05).Compared with model group, the level of plasma DAO and D-lactic acid significantly decreased in intervention groups(p<0.05); Compared with normal group, the level of serum MPO and TNF-α significantly increased in model group(p<0.05). Compared with model group, the level of serum MPO and TNF-α significantly decreased in intervention group(p<0.05); The level of serum MPO in positive control group and DF group was significantly lower than that in model group(p<0.05). However, the level of serum MPO in sweet potato powder group had no significant difference with model group.4. Preparation and quality examination to tablets of DF from sweet potato: tabletting formulation of DF from sweet potato was defined by screening suitable raw material and auxiliary material.The formulation was as follow:the dosage of soluble DF,insoluble DF and pregelatinized starch was 15wt%,45wt% and 40wt%(the amount of the three materials above was considered as measurement baseline),in the addition,the dosage of10% starch paste,xylitol, D- fructose and magnesium stearate was 20-30wt%,6wt%,6wt%and 1wt% respectively.Results of quality examination to tablets of DF showed that the quality of DF tablets met the requirements of the State Pharmacopoeia for tablets.Conclusion:Dietary fiber from sweet potato was prepared by the combined technology of enzymolysis with alkaline hydrolysis in this paper,the suitable variety of sweet potato for preparing dietary fiber was determined by indicators of the yield of dietary fiber and content of soluble dietary fiber,the optimal preparative process was defined by single factor and orthogonal array design experiments.After identifying the quality of dietary fiber from sweet potato, the preventive and therapeutic effect of dietary fiber from sweet potato for ulcerative colitis was explored initially, rat model of ulcerative colitis was successfully constructed and the efficacy of sweet potato in traditional chinese medicine and dietary fiber in modern medicine for preventing and treating ulcerative colitis was verified, preliminary results suggested that the efficacy of sweet potato on UC was connected with DF that it was rich in, that whether DF was the unique material basis of sweet potato preventing ulcerative colitis required in-depth study further.Finally, the preparing recipe of tablet of dietary fiber from sweet potato was also explored and qualified tablet product was prepared successfully.