Abstract: The purpose of this study was to evaluate the effect of high pressure homogenization conditions on the physical and oxidative stability and microstructure of two different O/W emulsion-based systems, prepared with Maillard reaction products (MRPs) from sodium caseinate with glucose (NaCN-glu) and sodium caseinate (NaCN) as the emulsifier, respectively for the delivery of docosahexaenoic acid (DHA). The physical and oxidative stability and microstructure were evaluated by a vertical scan analyzer (Turbiscan), measurement of total oxidation value (TOTOX) and confocal laser scanning microscopy. The results showed that the NaCN emulsion was found to be much less stable than the NaCN-glu emulsion under the same conditions, and sodium caseinate had excellent emulsifying properties and antioxidant activity after Maillard reaction modification. Moreover, homogenization pressure and cycles had a significant impact on emulsion stability and microstructure. Better NaCN-glu emulsion was obtained through high-pressure homogenization at 95 MPa performed for 3 times. Turbiscan analysis showed that slight creaming at the top and clear bottom were found for the emulsion, with a Turbiscan stability index (TSI) of 1.55, which was lower than that of the other groups; the TOTOX value was the lowest at each time point during storage for up to 28 d at 25 ℃. Confocal laser scanning microscopy revealed smaller uniform droplets with intact morphology mainly distributed between 0.47 and 0.59 μm.

Key words: Millard reaction products of sodium caseinate with glucose, docosahexaenoic acid algae oil emulsion, physical stability, oxidative stability