Study On Enzymatic Synthesis Of Amylodextrin From Sucrose

Amylodextrin has a good solubility in water, thus it is widely used in food, medicine andother areas. The properities of amylodextrin mainly depend on its average degree ofpolymerization(DP), but the DP of amylodextrin prepared from existed methods can not becontrolled. In this article, we studied enzymatic synthesis of amylodextrin by sucrosephosphorylase (SP) and glucan phosphorylase (GP) from sucrose, set the preparationconditions, and realized the controllability of amylodextrin DP, and will provide thereticalbasis for industrial production.On the premise of determination of glucose-1-phosphate (G-1-P) by LC-MS, we studiedthe influence of sucrose concentration, SP concentration, pH and reaction time on conversionrate from sucrose to G-1-P. Single factor and response surface analysis experiments show thatthe optimum conditions are as follows: sucrose concentration0.10mol/L, SP concentration4.5U/mL, pH6.5, temperature40℃, reaction time4h. The conversion rate increased from37.5%to76.9%after optimization.On the premise of determination of amylodextrin by HPAEC-PAD, we studied theinfluence of G-1-P concentration, maltotetraose concentration, GP concentration, pH andtemperature on the synthesis of amylodextrin. Single factor and orthogonal experiments showthat the optimum conditions are as follows: G-1-P concentration0.08mol/L, maltotetraoseconcentration0.04mol/L, GP concentration5.0U/mL, pH4.5, temperature40℃, reactiontime4h. The conversion rate from G-1-P to amylodextrin increased from30.3%to67.8%.Based on the above research, we studied the optimum co-reaction conditions with SP andGP, results are as follows: pH5.5, temperature40℃.The variation of amylodextrin DP according to reaction time and substrate proportion(sucrose/maltotetraose) were studied. Results show that: on the definite substrate proportionconditions, DP of amylodextrin increased with reaction time, yield of product DP5~10decreased from100%to56.4%while DP11~15increased from0to37.3%; on the definitereaction time conditions, the DP distributions were influenced greatly by substrate proportion,different DP distribution amylodextrin can be prepared at different substrate proportion, thuswe can realized the controllability of amylodextrin DP from5to40.The conditions of recovering the by-product fructose through Ca(OH)2precipitationmethod were studied, results show that: the optimum fructose concentration0.15~0.20g/mL,the volume ratio of reaction solution and Ca(OH)2precipitant is1:0.75. The recovery rate offructose from reaction solution at optimal conditions is95.3%.