Structuring and Functionalization of Dispersions Containing Egg Yolk, Plasma and Granules Induced by Mechanical Treatments

Abstract

In this study, the impact of mechanical treatments on the physicochemical and emulsifying properties of hen egg yolk and its fractions plasma and granules has been assessed. Yolk, plasma, and granule dispersions at pH 4.0 and 0.75 M NaCl were subjected to rotor-stator and high-pressure pretreatments at different dynamic pressure levels: 30, 100, and 200 bar at 20 degrees C. Physicochemical characteristics (protein solubility, rheological behavior, and micro- and ultra-structures) and emulsifying properties (oil/water 60:40 emulsions: droplet size and flocculation, protein adsorption) of control dispersions and dispersions subjected to mechanical pretreatments (rotor-stator or high pressure) were compared. Homogenization at high pressures (100 and 200 bar) led to a decreased protein solubility and to an increase in apparent viscosity of yolk and plasma dispersions. These pressures certainly disrupted low-density lipoproteins (LDL) particles and generated aggregates of proteins liberated from LDL and livetins in the plasma fraction, and led to a moderated reorganization of the microstructure of granules. Despite the modifications observed in the pretreated plasma and granules dispersions, the oil droplet diameter and the bridging flocculation obtained in emulsions made with these dispersions were similar to that obtained with untreated dispersions. Results concerning interfacial protein adsorption suggested that preformed or natural aggregates at least partially persist at the oil-water interface.

Rheological properties, stability and sensory evaluation of low-cholesterol mayonnaises prepared using egg yolk granules as emulsifying agent

“…Although, different studies about egg yolk granules have been carried out (Anton and Gandemer, 1997;Aluko and Mine, 1998;Le Denmat et al, 1999;Ibanoglu and Ercelebi, 2007;Sirvente et al, 2007), no important practical applications have been developed for them.…”

Impacto De Nuevas Tecnologías De Conservación Sobre La Estructura Y Los Principales Componentes Químicos De Alimentos Fluidos

“…Moreover, some proteins, as albumins, are especially sensitive to temperature, and it increases during the HPH treatment. Some authors (Sirvente et al, 2007) (Floury et al, 2002). After one week of refrigerated storage similar effects were observed.…”

“…Sin embargo, no existen prácticamente estudios sobre el efecto de esta tecnología en la composición, propiedades fisicoquímicas y sensoriales del huevo, así como en sus propiedades tecnológicas, lo que hace necesario su estudio. Únicamente Sirvente et al (2007) estudiaron el efecto de las HPH en la estructura, propiedades fisicoquímicas como la solubilidad y reología y las propiedades emulsionantes de dispersiones de yema de huevo, a presiones de homogeneización de hasta 20 MPa, observando un descenso en la solubilidad de proteínas y un aumento en la viscosidad, especialmente en la fracción del plasma. Además, el tratamiento a estas presiones rompió las partículas de lipoproteínas de baja densidad y formó agregados entre las proteínas liberadas y las livetinas del plasma, pero no afectó apenas a la microestructura de los gránulos.…”

Structural Study on Hen-egg Yolk High Density Lipoprotein (HDL) Granules

“…Egg yolk is a natural oil-in water emulsion where lipids and proteins are organized in supra-molecular assemblies with different organization levels [1]. Egg yolk is widely used as a food ingredient because of the high biological value of its components [2] and their excellent emulsifying [3] and stabilizing properties in gels and emulsions [4].…”

“…In the plasma of egg-yolk, the sizes of LDL micelles range from 17 to 60 nm with an average of 30 nm [7]. The precursor of LDL micelles (VLDL) is also present in egg-yolk with sizes ranging from 80 to 350 nm [1]. Beside a distribution in size, LDL particles vary also in surface charge and composition [6].…”