Study On The Catalytic Degradation Process Of High Polymer Procyanidins Form Lotus Seed Pot

According to the records,there is a large amount of procyanidins in the lotus seed pot.Its highly effective antioxidant and pharmacological activities can eliminate free radicals and fight cancer.The extraction and separation of procyanidins can be used to make deeper use of lotus plants,and also to avoid environmental pollution.According to the degree of polymerization,procyanidins can be divided into oligomeric procyanidins and high polymer procyanidins.Studies have shown that the biological activity of procyanidins has a negative correlation with the degree of polymerization.The oligomeric procyanidins（2≤average degree of polymerization≤5）have a higher biological activity and the dimer is the highest.The procyanidins in lotus seed pot are mainly composed of high polymers（average degree of polymerization>5）.In order to improve the utilization efficiency of procyanidins,the study of attempting to degrade high polymers into oligomers have attracted attention gradually in recent years.The content of dissertation was summarized as follows:1.Solvent extraction of procyanidins in lotus seed pot was performed,and organic fractionation was performed according to the degree of polymerization.With reference to the modified vanillin method,a standard curve was experimentally established to determine the average degree of polymerization of the product.The results showed that the extraction rate of procyanidins in lotus seed pot was 7.33%,of which the mass of the high polymer procyanidins accounted for 93.45%,and the mass of oligomeric procyanidins accounted for 6.55%.The degree of polymerization was determined separately.The average degree of polymerization of procyanidins in the crude extract was 5.28,the average degree of polymerization of the high polymers was 5.95,and the average degree of polymerization of the oligomer was 4.66.2.Sulfurous acid was selected as acid degradation agent and degraded the high polymer procyanidins.On the basis of single factor experiments,the orthogonal test and verification test were designed to determine the suitable process.The acid dosage was 7.5 mL/5 mL,the reaction temperature was 80℃,and the reaction time was 50min.Under this condition,the average degree of polymerization of the sample decreased from 5.95 to 3.04.Among the influencing factors,the temperature had the greatest impact,followed by the acid dosage,and the effect of time wasn’t obvious.3.The idea of using solid acid to degrade the high polymer procyanidins was proposed for the first time.The SO₄^2-/TiO₂ solid acid catalyst was prepared,and was used to degrade the polymer procyanidins in the lotus seed pot.Then the effects of single factor variables on the degradation reaction were studied.On this basis,the orthogonal test and verification test were designed to determine the appropriate degradation process conditions:2 mol/L H₂SO₄ was loaded on P 25 Ti O₂,then prepared SO₄^2-/TiO₂ solid acid as a catalyst,acid dosage was 0.04 g/10 mL.The reaction temperature was 70℃and the reaction time was 60 min.Under this reaction condition,the degree of polymerization of the sample reduced from 5.95 to2.31.The order of importance of factors was:reaction temperature>solid acid dosage>reaction time.The properties of the prepared solid acid catalysts were characterized by FT-IR and BET analysis;the results of the degradation experiments were proved by UV spectroscopy and gel chromatography.Compared with the degradation data in the existing related literature,the catalytic degradation rate of the solid acid is relatively high.At the same time,the average degree of polymerization of the degraded procyanidins also reached the highest active dimer.4.The catalytic degradation mechanism of solid acid was studied initially.In order to increase the yield of the oligomeric procyanidins and realize the regeneration of the solid acid catalyst,experimental studies were performed on the desorption of procyanidins on solid acid catalysts after the reaction.The solid acid catalyzed degradation reaction of procyanidins conformed to the L-H first-order reaction kinetics equation and had a good correlation.At 70℃（suitable degradation temperature）,the kinetic equation was ln（C₀/C_t）=0.0066 t+0.2420.For the procyanidins adsorbed on the solid acid catalyst,70%ethanol solution was used as the desorbent.Stir in water bath at 50℃for 1 h.By this method,the total yield of oligomeric procyanidins could reach 88.86%.