Controlled release of methylene blue from glutaraldehyde-modified gelatin

Gelatin has been identified as a valuable material for controlled release of food ingredients because of its highly ramified three-dimensional network. In the present work, gelatin was further modified with glutaraldehyde (GA) and prepared as microspheres to further improve its control to release of food ingredients. Features (i.e., chemical structures, thermal properties, network structures, and methylene blue (MB) release kinetics) of both the unmodified and GA-modified gelatin microspheres were investigated. Results showed that the application of GA enhanced the formation of intramolecular and/or intermolecular crosslinking of gelatin and improved its thermal stability. Besides, the release efficiency of MB from the GA-modified gelatin was less affected by temperature and pH value compared to the unmodified gelatin. Kinetics analysis proved that the release of MB from gelatin followed the first-order kinetics. Both the release constant (k) of MB and the diffusion coefficient (D_a ) of GA-modified gelatin were significantly lower than those of the unmodified gelatin. PRACTICAL APPLICATIONS: Gelatin is a valuable material for the release control of food ingredients (e.g., oils, vitamins, antioxidants, and flavor compounds) attributes to its highly ramified three-dimensional network. However, the low mechanical strength of gelatin makes it susceptible to many environmental factors and has restricted its application. In the present work, gelatin was modified by glutaraldehyde (GA). The chemical structure, thermal properties, network structure, and methylene blue release kinetics of the GA-modified gelatin microspheres were properly investigated. This research proved that GA-modified gelatin could be a potential carrier for the release control of given food contents in food industry.