Study on the antioxidant activity and emulsifying properties of flaxseed gum-whey protein isolate conjugates prepared by Maillard reaction.

The antioxidant and emulsifying properties of flaxseed gum-whey protein isolate (FSG-WPI) conjugates prepared by Maillard reaction via controlled dry-heating were investigated. The reaction was carried out using a ratio of FSG to WPI of 1:3 at 60 °C and 79% relative humidity for different incubation times. The reaction was confirmed by analysis of the browning index, free amino content and soluble sulfhydryl content, as well as by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, ultraviolet-visible spectroscopy, and Fourier transform infrared spectroscopy. We found that nearly 35% of the protein participated in conjugation with FSG after 48 h of incubation. The antioxidant activity of the conjugates improved markedly after 48 and 72 h incubation time. Differential scanning calorimetry results indicated that the denaturation temperature of the conjugates increased. The FSG-WPI conjugate prepared by 72 h incubation had the best emulsifying properties in stabilizing an oil-in-water emulsion. This research provides significant knowledge for the potential applications of FSG in food industry.