高取代度磷酸魔芋葡甘聚糖酯的制备

Preparation of konjac glucomannan phosphate ester with high degree of substitution

以魔芋葡甘聚糖(konjac glucomannan,KGM)、Na H_2PO_4与Na_2HPO_4混合盐为原料,采用真空辅助微波半干法制备高取代度磷酸魔芋葡甘聚糖酯(konjac glucomannan phosphate ester,KGMP),通过单因素试验研究了微波时间、微波温度、酯化剂与KGM摩尔比、真空处理时间、p H值、尿素用量对取代度的影响,并通过响应面试验确定最佳工艺参数并研究所得产物的基本性质。结果表明,真空辅助微波半干法制备高取代度KGMP的最佳工艺条件:微波时间7 min、微波温度100℃、磷酸盐与KGM摩尔比为0.72∶1、真空处理时间29 s、p H值5.0、尿素用量(质量分数)6%,KGMP的取代度为0.199;随着取代度的增加,产品的黏度适度降低,透光率增加;红外光谱表明,KGM上引入了磷酸基团,得到KGMP。

Using microwave irradiation with vacuum-assisted method,konjac glucomannan phosphate ester (KGMP) with high degree of substitution was produced by semi-drying konjac glucomannan (KGM) and the mixture of NaH2PO4 and Na2HPO4.Based on single-factor experiments,effects of microwave time,microwave temperature,molar ratio of esterifying agent to KGM,vacuum treatment time,pH value,and urea dosage on the degree of substitution of KGMP were studied.The results showed that the optimal conditions were as follows:at pH=5.0,microwaving at 100 ℃ for 7 min,with 0.72∶1 as the molar ratio of esterifying agent to KGM,vacuum treating for 29 s,and with 6% urea.The substitution degree of KGMP was 0.199.With increasing substitution degree,the product viscosity decreased,and the light transmittance significantly increased.Infrared spectroscopy indicated that phosphate groups were introduced to KGM,confirming the formation of KGMP.