Use of soluble chitosans in Maillard reaction products with β-lactoglobulin. Emulsifying and antioxidant properties

The reaction of commercially available soluble chitosans of equal acetylation degree (11-12%) and differing in their molecular weight (56-1.3 kDa) and β-lactoglobulin by Maillard reaction has been conducted in order to evaluate the resulting products and their functional properties. The characterization of the reaction products was performed by measurement of z-potential interactions, solubility, size exclusion chromatography, electrophoretic pattern, and absorbance and fluorescence spectroscopic compounds formation. Higher molecular weight chitosans (39 and 56 kDa) showed a slow progression and a gelled insoluble material appeared. In filtered products, emulsifying properties of the conjugates were improved with regard to those of the unreacted protein. Conjugates formed with the enzymatically depolymerized chitosan (1.3 kDa) displayed a sharp formation of advanced and final products of Maillard reaction. Products with all three chitosans gave rise to antioxidant activity superior to the protein after 2 days of reaction (2 and 3 times in ferric reducing power for 39 and 56 kDa chitosans, and 7 times for the 1.3 kDa chitosan, respectively), and the values correlated well with the spectroscopic and fluorescent compounds from the Maillard reaction. The results are useful with a view to selecting chitosans for development of new ingredients with tailored functional properties.