Sodium caseinate-corn starch hydrolysates conjugates obtained through the Maillard reaction as stabilizing agents in resveratrol-loaded emulsions

Abstract

Functional properties of proteins can be improved by inducing the Maillard reaction in protein-carbohydrate mixtures. Wet-heating methods have been less explored than dry-heating for this purpose, despite its advantages such as faster reaction and the non-requirement of the lyophilization stage. Our work main goals were to produce Maillard-glycated products with sodium caseinate, maltodextrin and dried glucose syrup, using wet-heating conditions, and to evaluate their emulsifying properties in resveratrol-loaded emulsions. Protein-polysaccharide conjugates were prepared by heating aqueous mixtures at 75 °C from 0 (control sample) to 24 h. Changes in pH, colour, ζ-potential, antioxidant capacity (AOC), electrophoretic and size exclusion chromatography profiles were monitored. The conjugates were used to stabilize resveratrol-loaded emulsions, which were characterized by droplet size, kinetic stability, ζ-potential, AOC and interfacial properties. Increased heating times gave products with lower pH, more intense brown colour, higher AOC and formation of high molecular mass compounds. Emulsions produced with these conjugates showed larger droplet size, improved kinetic stability and higher AOC compared to the control emulsions (prepared with the control sample). Resveratrol increased droplet size and marginally affected interfacial tension. Wet-heating was efficient to produce Maillard-glycated conjugates with high potential use as emulsifying/encapsulating agents, with antioxidant properties, capable of providing extra protection to bioactive compounds such as resveratrol.