Enhancing The Stabilization Of Beta-Carotene Emulsion Using Ovalbumin-Dextran Conjugates As Emulsifier

A simple reliable way of improving the emulsifying behaviour of a protein is through covalent binding with a polysaccharide. Thus the effects of ovalbumin (OVA) after modified by dextran (Dex) under traditional wet heating (WH) or microwave heating (MH) on stabilisation and digestion of alpha-carotene emulsions were comprehensively studied. The emulsifying activity and emulsion stability of OVA were improved significantly after Dex covalent modification under WH or MH condition. OVA-Dex-MH conjugates performed better than OVA and OVA-Dex-WH conjugates in producing an extremely narrow size distribution and high encapsulation rate of beta-carotene in emulsion. In addition, OVA-Dex-MH conjugates were considerably more effective in oil droplet stabilization against acidic/alkaline conditions (pH 3.0-10.0), high ionic strength (150 mM NaCl) and high temperature (90 degrees C for 30 min), consistent with the results of apparent viscosity analysis that the flow behavior index of beta-carotene emulsions stabilized by OVA-Dex conjugates decreased compared with that of OVAstabilized emulsion. Moreover, in the first 30 min of digestion, the degrees of lipolysis in emulsions stabilized by OVA, OVA-Dex-MH, and OVA-Dex-WH conjugates were 60.88%, 80.77%, and 75.32%. However, no significant difference was observed in the protein digestion and bio-accessibility of beta-carotene. These results proved that OVA-Dex-MH conjugates have the potential to form stable, food-grade emulsion-based delivery systems against environmental stresses.