Studies On The Preparation Of Porous Starch By Common Glucoamylase And Its Capability Of Adsorption

This paper mainly focused on the technology of produce porous starch, effect on the enzymatic hydrolysis capacity of common gulucoamylase with pretreatment, and capability of adsorption on porous starch.In the technology section, some glucoamylase and starches were tested to prepare porous starch. Fungal amylase and corn starch were chosen as the original amylase and substance respectively. The conditions of the fungal amylase acting on the raw corn starch were optimized, and the optimal conditions were obtained by single factor, Plackett-Burman test and regression analysis of RSM: enzyme amount was 500U/（g substance）, liquid-solid ratio was 2, pH was 5.0, the reaction temperature was 55℃and the reaction time was 24h.It was discussed the effect of pretreatment on the raw starch hydrolysis activities of glucoamylase in detail. After pretreated by ultrasonic, corn starch was easier hydrolyzed with better porous structure at the surface of starch granules. It was also discovered that the capability of enzyme hydrolysis was much more enhanced when fungal amylase acted on heat-moisture treated （HMT） sweet potato starch, compared with ultrasonic pretreated starch. But it was a pity that neither was formed porous structure after enzymatic hydrolysis.The optimum conditions of ultrasonic pretreatment were ultrasonic power of 400w, ultrasonic time of 15min and container diameter of 7cm. At this optimization strategy of ultrasonic pretreatment and enzyme hydrolysis conditions, 11 hours was economized according to literature when got to the same 50% extent of enzyme hydrolysis. The optimum conditions of heat-moisture treated sweet potato starch were treatment temperature of 90℃, origin starch humidity of 33%, treatment time of 120min.The capability of adsorption and sustained release for Aminophylline in porous starch was studied. The optimum adsorptive conditions were obtained by single factor test: the origin concentration of Aminophylline was 50mg/mL, pH was 9.5, adsorptive temperature was 20℃, and adsorptive time was 60min. The highest adsorptive amounts were 403.58mg/g, increasing 12.5 times compared with the ones of raw starch. The capability of sustained release for Aminophylline in porous corn starch was validated. The release percentage was 28.26% at the first hour and 15.43% at the second hour. At the next 8h, the release percentage was 5% per hour. The cumulative release percentage was 82.64% for 10h.The adsorptive amount of Aminophylline in heat-moisture pretreated and enzymatic hydrolyzed sweet potato starch were 200.57mg/g under the optimum conditions as followed: the origin concentration of Aminophylline was 50mg/mL, pH was 9.5, adsorptive temperature was 40℃, and adsorptive time was 40min. The equation of velocity for Aminophylline was Q=148.26t^0.742.The raw starch hydrolysis activities of glucoamylase was obviously enhanced with the methods of ultrasonic and heat-moisture pretreatment. And porous corn starch with good appearance of porous structure was prepared, that had a good capability of adsorption on Aminophylline. This research has established a base for further study and more application of porous starch in future.