Fabrication and characterization of emulsion stabilized by table egg‐yolk granules at different pH levels

Abstract

BACKGROUND: The egg yolk is complex, which makes it difficult to understand why mayonnaise can be stabilized into a high internal-phase emulsion. This study aimed to assess the possibility of developing oil-in-water emulsions through unmodified natural egg-yolk granules (EYGs) at various pH levels, to further understand the precise mechanism of mayonnaise. RESULTS: Egg-yolk granules were obtained from hen egg yolk by centrifugation. The sizes of the EYGs were characterized using dynamic light scattering (DLS). Zeta potential of EYGs was detected by DLS and its microstructure was observed by microscope and scanning electron microscope (SEM). Oil / water emulsions were made with EYGs and the size distribution and creaming index of those emulsions were measured at different storage times (1 h and 14 days). The interfacial morphology of EYGs was observed using the emulsion polymerization method. Our results suggested that the prepared EYGs were mainly in an aggregated state but individual EYGs displayed spherical shapes, with a size of 1.0 ± 0.2 m. The emulsion stabilized by EYGs displayed better stability against creaming at acidic pH (<4.0). At the same time, the interfacial morphology and microscopic observation of the emulsions strongly demonstrated that the emulsions were of the Pickering type. CONCLUSION: The above results are of great importance for an understanding of the mechanism by which mayonnaise is stabilized by egg, together with the applications of egg in food formulations.

Formation of Natural Egg Yolk Granule Stabilized Pickering High Internal Phase Emulsions by Means of NaCl Ionic Strength and pH Change

“…Previous studies also found decreasing trend in particle size of emulsion stabilized by EYGs as the pH increased from 3.0 to 9.0 at NaCl ionic strength of 0.15 M [ 20 ]. In addition, among all gel-like emulsions, the particle size of the emulsion at pH 5.0 was the largest, which was similar to other researchers’ studies [ 15 ]. However, the decreasing trend of emulsion particle size as the pH value moved away from the isoelectric point (pH 5.0) was contrary to the study by other researchers [ 15 ].…”

“…As shown in Figure 1 B, the isoelectric point of EYGs was close to 5.0. However, in the absence of NaCl salt ions, the isoelectric point of the EYGs was 4.0 instead of 5.0 [ 15 ]. Similarly, it had also been found that the isoelectric point of the EYGs was between 4.0 and 5.0 with the addition of 0.15 M NaCl in solution [ 20 ].…”

“…Thus, EYGs with high solubility are possible to be obtained by adjusting pH and NaCl ionic strength in order to prepare emulsions with high oil content. Recent studies have confirmed that EYGs were able to stabilize 75% of the oil, and the formed emulsions were gel-like, suggesting that EYGs could be used to stabilize HIPEs [ 15 ]. However, the preparation of stable Pickering emulsions by means of EYGs and the role of EYGs in stabilizing them are still not clear.…”

Mayonnaise main ingredients influence on its structure as an emulsion

“…Also, they found that with increasing oil content, the pH of mayonnaise increased especially when the oil phase volume fraction is ([ 0.5). In the study conducted by Wang et al (2020), authors found that by decreasing the pH of mayonnaise, its stability improved and creaming was not accrued. They mentioned that, one reason could be through increasing the oil droplets size with the pH enhancement.…”

Novel Pickering High Internal Phase Emulsion Stabilized by Food Waste-Hen Egg Chalaza

“…Recently, the U.S. Food and Drug Administration (FDA) stated to ban the utilization of PHOs in processed food [16]. To meet the new requirements, an effective alternative of PHOs which could mimic the rheology and sensory features of the PHOs are the new challenges for food scientists [17][18][19][20][21]. Oleogelation, which uses the three-phase emulsion system to physically fabricate the artificial butter-like product, is a promising way to meet the increasing demand for healthier food.…”