N-乙酰化程度对壳聚糖稳定Pickering乳液乳化性能的影响

Effect of N-Acetylation Degree on the Properties of Chitosan-Stabilized Pickering Emulsions

本研究旨在利用将乙酰基共价接枝到多糖链上的修饰策略以改善壳聚糖的乳化性能,并探究最佳乙酰化范围。红外谱图验证了乙酸酐重乙酰化工艺能调控壳聚糖的乙酰度,并且取代只发生在C2位的氨基上。接触角分析结果表明乙酰化能有效提高壳聚糖的非极性部分,致使其乳化性增强,修饰后的壳聚糖稳定Pickering乳液的液滴尺寸显著降低,当乙酰度为32%时,壳聚糖稳定Pickering乳液的乳化活性指数和乳化稳定性增至最大(分别为39.56 m^(2)/g和65.54 min),乳液的平均液滴尺寸达到最小(12.71μm),乳液稳定性增加,乳析指数下降明显(下降至11.3%)。综上,改变壳聚糖上N-乙酰-D-氨基葡萄糖单元的物质的量比可以有效改善壳聚糖的乳化性能和所稳定乳液的贮藏稳定性。

The aim of this study is to apply a modification strategy based on covalently grafting acetyl groups onto polysaccharide chains to improve the emulsifying properties of chitosan.A second aim is to explore the optimal degree of acetylation(DA).Infrared spectroscopy(IR)confirmed that acetic anhydride reacetylation could regulate the DA of chitosan,and substitution only occurred on the amino group at the C2 position.The contact angle results showed that acetylation could effectively improve the non-polar part of chitosan,resulting in enhanced emulsifying properties.The droplet size of the Pickering emulsion stabilized by the modified chitosan significantly decreased compared with that observed with untreated chitosan.The emulsifying activity index(EAI)and emulsion stability index(ESI)of acetylated chitosan with 32%DH were the highest(39.56 m^(2)/g and 65.54 min,respectively),and the average droplet size of the emulsion was the smallest(12.71μm).In addition,the creaming index(CI)decreased significantly to 11.3%compared with that using untreated chitosan.It is proved that changing the molar proportion of N-acetyl-D-glucosamino units in chitosan can effectively improve the emulsifying properties of chitosan and the storage stability of emulsions.