Kosaraju Shantha Lakshmi, Weerakkody Rangika, Augustin Mary Ann
CSIRO Food and Nutritional Sciences, Private Bag 16, Werribee, Victoria 3030, Australia.
J Agric Food Chem. 2010 Dec 8;58(23):12449-55. doi: 10.1021/jf103484z. Epub 2010 Nov 10.
Chitosan-glucose conjugates were prepared using Maillard reaction chemistry. Water-soluble and acid-soluble chitosan-glucose mixtures were heated at pH 4.9 and 6.0 at 98 °C. Mixtures at pH 6.0 containing acid-soluble chitosan gelled when heating was continued after reaching 98 °C and withstood gelation for only 30 min at pH 4.9. In contrast, mixtures containing water-soluble chitosan could be heated without gelation at pH 6.0 and 4.9. Examination of the extent of Maillard reaction and antioxidant properties showed that acid-soluble chitosan reacted for 30 min at pH 4.9 had the highest extent of reaction as judged by increased absorbance, the highest degree of modification to the amino group as evidenced by Fourier transform infrared and shifts of the endotherms by differential scanning calorimetry, and the highest antioxidant activity as indicated by ferric reducing power and oxygen radical absorbance capacity. There were significant correlations (p < 0.05) between indices of browning and antioxidant activity.
壳聚糖-葡萄糖共轭物采用美拉德反应化学法制备。将水溶性和酸溶性壳聚糖-葡萄糖混合物在pH值为4.9和6.0、温度为98°C的条件下加热。在pH值为6.0且含有酸溶性壳聚糖的混合物在达到98°C后继续加热时会发生凝胶化，而在pH值为4.9时仅能耐受30分钟的凝胶化。相比之下，含有水溶性壳聚糖的混合物在pH值为6.0和4.9时加热不会发生凝胶化。对美拉德反应程度和抗氧化性能的检测表明，通过吸光度增加判断，在pH值为4.9时反应30分钟的酸溶性壳聚糖具有最高的反应程度，通过傅里叶变换红外光谱以及差示扫描量热法测定的吸热峰位移证明其对氨基的修饰程度最高，通过铁还原能力和氧自由基吸收能力表明其具有最高的抗氧化活性。褐变指数与抗氧化活性之间存在显著相关性（p < 0.05）。
