High-Pressure Induced Physicochemical and Functional Modifications of Low-Density Lipoproteins from Hen Egg Yolk

Abstract

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.

Culinary Biophysics: on the Nature of the 6X°C Egg

“…43,46,47 The broad peak at ∼80°C is expected to correspond to the most abundant proteins in yolk, LDL, which is confirmed by studies on pure human LDL. 48 However, in pure egg LDL at pH 8 the peak is reported at ∼70°C, 49 thus DSC experiments do not clarify the matter. Stability studies have reported that LDL is stable below 60°C, but it is fully aggregated after heating it at 70°C for 5 min, 44 while higher temperatures are reported for shorter heat treatments (72-76°C for 2.5 min.…”

Study on aggregation behavior of low density lipoprotein in hen egg yolk plasma by asymmetrical flow field-flow fractionation coupled with multiple detectors

“…3. treatment provokes a denaturation of LDL, leading to a disruption of the LDL structure and a reorganization by aggregation of LDL components (Speroni et al, 2005). The results indicate that LDL most likely undergoes a 'cluster-fusion' aggregation mechanism upon sufficient heating.…”

“…Anton and coworkers purified LDL from egg yolk by gel filtration and found LDL to contain five major apoproteins While the effect of pH, ionic strength, processing and enzyme treatment on emulsion properties of egg yolk has been studied (Daimer & Kulozik, 2008;Guilmineau & Kulozik, 2006a, 2006bLe Denmat et al, 2000;Mine, 1998a), not much focus has been put on the effect of these parameters on LDL structure. One of the important functional properties of egg yolk plasma is its ability to undergo aggregation upon heat treatment, which plays an important role in the textural properties of final food products (Speroni et al, 2005). Heat stability is often desirable in emulsions, for instance to have the possibility to pasteurize them to assure microbiological safety etc.…”

“…Despite the versatility of AF4 for the study of complex biosamples and a range of food macromolecules and dispersions (Nilsson, 2013), AF4 technique has, to our knowledge, not yet been applied to egg yolk. At present, cryo-transmission electron microscopy (Cryo-TEM) and quasi-elastic light scattering (QELS) have been used for the size determination of egg yolk plasma components (Anton, 2013;Speroni et al, 2005;Yohannes et al, 2010). Cryo-TEM provides information on both the morphology and the size distribution of the sample at the same time.…”

Changes in physicochemical properties of egg white and yolk proteins from duck shell eggs due to hydrostatic pressure treatment

“…Egg yolk is widely used in the food industry due to the excellent functional properties of its lipoproteins, such as flavor, aroma, color, viscosity, emulsifying, and foaming (Fennema, 1993). Denaturation of egg yolk proteins resulted in functional modifications, such as emulsifying and rheological properties (Ahmed et al, 2003;Speroni et al, 2005).…”