High-pressure induced physicochemical and functional modifications of low-density lipoproteins from hen egg yolk.

High-pressure treatment represents a potential method to stabilize microbiologically agricultural raw materials that are sensitive to heat treatments. Low-density lipoproteins (LDL), the main contributors to the exceptional emulsifying properties of yolk, are particularly sensitive to heat treatment. In this study, high-pressure treatments have been performed on LDL, and their impact on LDL physicochemical and emulsifying properties has been assessed. LDL dispersions at two pH levels (pH 3 and 8) were treated at different pressure levels: 200, 400, and 600 MPa at 20 degrees C. LDL dispersion characteristics (solubility, aggregation, and protein denaturation) and LDL emulsifying properties (o/w 30:70 emulsions: droplet size, flocculation, and protein adsorption) of nontreated and high-pressure treated dispersions were compared. Solubility is not altered by high-pressure treatment whatever the pH, whereas aggregation and protein denaturation are drastically enhanced, in particular at pH 8. The effects of these modifications on LDL emulsifying properties are mainly a diminution of the flocculation (depletion and bridging) at this same pH. Finally, it seems that high-pressure treatment combined with an alkaline pH decreases droplet flocculation of LDL dispersions.

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