Study On The Preparation Of Glucuronolactone With Starch

Glucurolactone is usually used as liver antidote and the main additive of healthcare products with immune function,which have the spacious extremely prospect and the meaningful research value.There are a lot of synthetic methods of glucuronolactone and the main is chemical oxidation.The traditional producing method of glucuronolactone is chemical oxidation that using the starch as raw material and concentrated nitric acid as oxidant, which existing many inadequacies,such as uncompletely of oxidation,poor selectivity with oxidant,more serious environmental pollution,low yield and difficult to control experiment process.To solve these problems,in this paper,we have discussed a processing route of preparation glucuronolactone, which technology are characterized by green environmental protection and clean production. As follows:Using the potato starch as raw material,it is usually necessary to destroy the long molecular chains and increase the specific surface area of starch,that could be realized by ultrasonic and pasting,which lead to the crystallinity decreased and the efficiency of oxidation improved.Then the oxidation starch with 6-carboxyl was obtained by the technology of fenton reagent oxidantion. the oxidation starch has been degraded by the a-amylase and glucoamylase,then the glucuronic acid could be obtained by the processes of fermentation and concentration.Finally,based on the esterification reaction,the glucuronolactone was synthesized by glacial acetic acid and acetic anhydride.In ultrasonic treatment stage, the effect of ultrasound on the starch structure has been investigated,in which the variation of crystallinity of starch is proved by IR,SEMandXRD,the changes of properties with starch are demonstrated by DSC,gelatinization degree,amylose content and viscosity.In oxidation phase, the effect of the content of H2O2 and FeSO4,reaction temperature and time on the oxidation process were studied,which the amylose content of oxidized starch was regarded as evaluation standard.In stage of liquefaction and saccharification, the glucuronic acid of liquefying and saccharifying liquid be used as evaluation standards,the effect of the amylase and glucoamylase do sage, temperature and pH the hydrolysis time on the degradation process have been studied.During the fermentation process, using the content of glucuronic acid as a evaluating parameter,the effect of the yeast powder dosage,fermentation temperature and time on the result of removing impurity have been studied.finally,under the esterification process,to study the effect of the amount of glacial acetic acid and acetic anhydride,the optimum of temperature and time,steam out of the amount of glacial acetic acid on the esterification technology,then the content of glucurolactone crystal could be regard as standard.The results are as follows:(1) In ultrasound treament processing,the SEM outcome showed that both the degree of rough with starch surface and the specific surface area are increased.the crystallinity of starch after ultrasounding decreased using IR. The result of XRD showed that the crystalline region smaller than that before ultrasound treament. Finally,the starch performance datas proved that,by the ultrasound,which the degree of gelatinization and the amylose content of starch have been increased gradually.Meanwhile,The temperature of gelatinization with starch could be promoted.while the viscosity of starch has been decreased effctively. the optimal conditions with ultrasound would be studied that 25 KHz for 50 min.(2) In oxidantion processing,using the fenton reagent as selectivily oxidants, the carboxyl content of starch was regard as measure,it was found that at the condition of mass ratios of the starch and water for 1:3, ultrasonic at 35 KHz for 50 min, gelatinization temperature at 56℃ for 20 min,0.8 g FeSO4.20 mL H2O2.reaction at 50℃ for 4 h,the carboxyl content of obtained starch was 4.64%. By contrasting,the carboxyl content of starch after ultrasound treatment have been promoted 43.92% than which no ultrasonic processing,and then,the carboxyl content of starch gelatinized by heating have been promoted 9.04% than that not gelatinization.(3) In oxidized starch degraded by a-amylase and glucoamylase processing, The glucuronic acid of liquefaction and saccharification would be used as evaluation to determine the optimum conditions.It is concluded that the liquefying technology as follows:at the condition of 12mL a-amylase,pH 6.5,reaction at 85℃ for 60 min,the glucuronic acid content of hydrolysis liquid was 9.89%.Under the same liquefying conditions of oxidation starch,the optimum conditions of saccharification was described as:pH 6.5,reaction at 55℃ for 12 h and amount of glucoamylase was 1 mL in the 75 g of oxidation starch, the glucuronic acid content of saccharification liquid was 22.87%.(4) In ferment purification processing,the optimum ferment conditions is that:in the 25 mL saccharification liquid with 2.0 g yeast,temperature of 35℃ for 4 d. the glucuronic acid content of fermentation liquid was 28.03%.(5) In esterification processingThe optimum conditions of esterification is deteirmined by the content of the glucurolactone crystals:According to per 10 g liquid concentrating should inject of 10 mL of acetic anhydride and 20 mL glacial acetic acid,reaction at 48℃ for 2.5h.then the content of glacial acetic acid vapouring is equivalent by 30% of the total.At the moment,the glucurolactone crystals productivity is reach up to 68.76%.(6) The glucuronolactone were characterized by melting point tester, infrared spectrum, X-ray diffraction (XRD).