Lagaron José M, Fernandez-Saiz Patricia, Ocio Maria J
Novel Materials and Nanotechnology, Institute of Agrochemistry and Food Technology (IATA), CSIC, Apartado Correos 73, 46100 Burjassot, Spain.
J Agric Food Chem. 2007 Apr 4;55(7):2554-62. doi: 10.1021/jf063110j. Epub 2007 Mar 14.
ATR-FTIR spectroscopy has been used in this study to characterize the molecular mechanisms and kinetic processes that take place when a chitosonium acetate thin coating is put in contact with water solutions, Staphylococcus aureus solutions, microbial nutrient solutions, and with a high water activity TSA hydrogel medium to simulate the effect of direct contact with high moisture foods such as fresh meats, fish, and seafood products or beverages. The results of this work suggest that the biocide carboxylate groups that form when chitosan is cast from acetic acid solutions are being continuously evaporated from the formed film in the form of acetic acid (mechanism I) in the presence of environmental humidity, rendering weak biocide film systems. On the other hand, upon direct contact of the cast chitosonium acetate film with liquid water, water solutions, or the high moisture TSA hydrogel, a positive rapid migration, with a diffusion coefficient faster than 3.7 x 10(-12) m2/s, of protonated glucosamine water soluble molecular fractions (mechanism II) takes place from the film into the liquid phase, yielding strong antimicrobial performance and leaving in the remaining cast film only the non-water soluble chitosan fractions. Finally, this study describes a refined spectroscopic methodology to predict the antimicrobial properties of chitosan and gives insight into the capacity of chitosan as a natural biocide agent.
在本研究中，衰减全反射傅里叶变换红外光谱（ATR-FTIR）被用于表征当醋酸壳聚糖薄涂层与水溶液、金黄色葡萄球菌溶液、微生物营养液以及具有高水分活度的胰酪大豆胨水凝胶培养基接触时发生的分子机制和动力学过程，以模拟与新鲜肉类、鱼类、海鲜产品或饮料等高水分食品直接接触的效果。这项工作的结果表明，当壳聚糖从醋酸溶液中浇铸成型时形成的杀生物剂羧基，在环境湿度存在的情况下，以醋酸的形式从形成的薄膜中持续蒸发（机制I），从而形成较弱的杀生物剂薄膜系统。另一方面，当浇铸的醋酸壳聚糖薄膜与液态水、水溶液或高水分的胰酪大豆胨水凝胶直接接触时，质子化的葡萄糖胺水溶性分子部分（机制II）会以大于3.7×10⁻¹² m²/s的扩散系数从薄膜向液相发生正向快速迁移，从而产生强大的抗菌性能，并且在剩余的浇铸薄膜中仅留下非水溶性的壳聚糖部分。最后，本研究描述了一种精确的光谱方法来预测壳聚糖的抗菌性能，并深入了解壳聚糖作为天然杀生物剂的能力。
