Abstract: Maillard reaction products of sodium caseinate with glucose, lactose, galactooligosaccharides and polydextrose were prepared in a small-scale ultra-high temperature (UHT) device. The development of Maillard reaction was analyzed and the emulsifying properties of Maillard reaction products at different intervals were compared. The results showed that small sugars were more susceptible to Maillard reaction. A positive correlation existed browning index with the extent of Maillard reaction. Both the emulsifying activity and the degree of graft increased at first and then decreased, but there was no linear relationship between them. The maximum values of activity of Maillard reaction products of sodium caseinate with glucose, lactose, galactooligosaccharides and polydextrose were 0.63, 0.51, 0.55 and 0.48, respectively. The Maillard reaction products from sodium caseinate with glucose produced by heat treatment for 15 s at 130 ℃ had the highest emulsifying activity, which was significantly higher than that of other groups and equivalent to that obtained by water bath heating at 90 ℃ for 90 min together with a high emulsion stability of 123.88 min. The kinetic stability index of DHA-rich algae oil emulsion containing these Maillard reaction products was 1.5, significantly lower than that of the other groups (P < 0.05). In conclusion, glucose can be used as a promising glycosyl ligand for Maillard reaction to prepare a novel and efficient emulsifier. Moreover, this method can realize continuous production, greatly shorten the reaction time and improve the production efficiency and therefore it can provide a significant guidance for industrialized production.

Key words: Maillard reaction, sodium caseinate, emulsifying activity, emulsion stability, DHA-rich algae oil emulsion