Maillard conjugation as an approach to improve whey proteins functionality: A review of conventional and novel preparation techniques

Background: The covalent interaction between an amino group of a protein and a carbonyl group of a carbohydrate through Maillard reaction leads to the production of conjugates. The conjugation of carbohydrates to whey proteins (WPs) is of particular interest due to the substantial improvement in WP characteristics (heat, ionic strength and pH sensitivity). The improved heat stability of conjugated WPs can be effectively used in the formulation of infant formulas, as well as beverages and powders, where heat stability is a limitation. Several preparation techniques have been used, which each have their own advantages and disadvantages. Scope and approach: Initially, the biochemical properties of whey proteins as well as the basic principles of conjugate preparation are highlighted. In order to provide insights into traditional and current state-of-the-art preparation techniques, recent studies about WP-carbohydrate conjugation are reviewed. Key findings and conclusions: Recent studies have shown that the Maillard interaction between WPs and carbohydrates can be exploited to substantially improve the physicochemical properties of these proteins. These studies describe conjugate preparation using conventional (dry and wet heating) and novel (e.g. pulsed-field gradient, sonication, extrusion, high pressure, and electrospinning) techniques. Whereas dry heating has been extensively used in many studies as a conventional method for the production of the WP conjugates, recent research has been focused on new approaches to produce the conjugates on an industrial scale.