PhD candidate, University of Alberta
Investigate the potencial use of egg yolk to encapsulate and protect omega 3 fatty acids
Previous works from our research group have shown that egg yolk (EY) can be used as a carrier of n-3 PUFAS (polyunsaturated fatty acids). In the present study, we aimed to improve the efficiency of EY to encapsulate n-3 PUFAS by modifying it with the enzyme phospholipase A1 (PLA1) from Aspergillus oryzae. Fish oil concentrate was added into PLA1-treated EY to achieve concentrations of 2.7, 13.9 and 27.7g EPA/DHA per 100g of EY dry matter; treated and untreated EY were used as controls. The encapsulation was performed by homogenization using an Ultra Turrax at 24000 rpm. Particle size distribution (PSD), encapsulation efficiency and oxidative stability were assessed at time 0 and after one week of storage at 4-6°C. Dynamic light scattering was used to evaluate PSD, and propanal content to assess the oxidative stability. The encapsulation efficiency was measured by quantifying the total and surface EPA/DHA. A Randomized Complete Block Design with three replicas was used as experimental design; significant differences were evaluated at α=0.05. Samples containing 27% EPA/DHA had the highest particle size; however, particle size for all samples remained constant after one week of storage, thus showing particle stability. Samples containing 2.7 and 13.9% EPA/DHA showed the highest encapsulation efficiency (>90%); nevertheless, no differences were observed within samples after one week of storage. No propanal content was detected in the samples during the time evaluated. These results suggest that PLA1-treated egg yolk is a suitable carrier to enhance the oxidative stability of omega-3 fatty acids.
Abstract: The objectives of this study were to understand the interactions between three anionic polysaccharides (gum arabic, xanthan gum and ι-carrageenan) and egg yolk at pH 3, 5, 6, 8, 10 and possible phase separation behavior. Zeta potential of egg yolk was not affected by gum arabic addition while it became more negative at pH 5 after xanthan gum and ι-carrageenan addition. The particle size of ι-carrageenan yolk suspension was considerably higher than the other polysaccharide yolk suspensions at pH below 6 but was dramatically decreased at alkaline pH. Most polysaccharide yolk suspensions formed either a biphasic or a monophasic system, whereas three distinct phases were observed for xanthan gum yolk suspension at pH 6. Protein profile analysis of the lipid-rich cream phase obtained from xanthan gum added yolk showed similarities to apoproteins from low density lipoproteins (LDL) of egg yolk. Microscopy analysis indicated the co-presence of xanthan gum and LDL in the creamy phase, within a network formed by xanthan gum. It was suggested that electrostatic and hydrophobic interactions between the egg yolk and xanthan gum as well as xanthan gum's rheological properties could be responsible for the unique phase separation observed in the study. The findings of this study can form the basis for future studies to develop a new method to separate LDL from egg yolk.
Pub.: 17 Dec '14, Pinned: 28 Jun '17
Abstract: Among dietary carotenoids, lutein and zeaxanthin are known to protect against age-related macular degeneration, a leading cause of irreversible vision loss in the elderly. Egg yolk is rich in lutein and zeaxanthin, however, the effect of cooking and gastrointestinal digestion on yolk carotenoids is poorly understood. An in vitro dynamic gastrointestinal model (TIM-1) was used to investigate the digestive stability and bioaccessibility of carotenoids from boiled, fried, and scrambled eggs. Bioaccessibility but not digestive stability was significantly affected by the method of cooking. The main egg carotenoids, all-E-lutein and all-E-zeaxanthin, were stable during the digestion with average recoveries of 90 and 88%, respectively. No trans-cis isomerization of carotenoids was observed during digestion. Both all-E-lutein and all-E-zeaxanthin from scrambled eggs showed significantly lower bioaccessibility compared to boiled eggs. The results indicate that the bioaccessibility of egg carotenoids can be affected by different food preparation methods.
Pub.: 10 Mar '15, Pinned: 28 Jun '17
Abstract: The physical properties and thermal stability of gelatin/gum-Arabic microcapsules loaded fish oil, developed by various encapsulation techniques such as directly spray-dried microcapsule, complex coacervation microcapsule, and double-encapsulated microcapsule (DEM) were investigated. All the particles dried by spray drying and evaluated by scanning electron microscopy (SEM), thermal analysis, cumulative release analysis, and rheological measurements. The external and internal core–shell structure of microcapsules observed by SEM, were beneficial to improving the thermal stability of particles. The DEM possessed stable two-shell structure, and retained 25.39% weight after thermogravimetric analysis, 93.71% encapsulation efficiency only released 11.8% core material in 100 °C water bath over 30 min, which could perform more stable during processing, transportation, and consumption. Above all, these results could be the basis of selecting suitable encapsulation technique, processing temperature, and time control in practical production when functional microcapsules needed.This article is aimed at characterize structures, relative physical properties and thermal stability of three types of microcapsules: directly spray-dried microcapsules, complex coacervation microcapsules, and double-encapsulated microcapsules, for encapsulating fish oil during processing and storage. Therefore, all the results such as encapsulation efficiency, loading capacity, surface oil, particle size, thermal stability, and fish oil cumulative release percentage of microcapsules at certain temperature could be used as guidance on practical functional foods production like selecting a suitable encapsulation approach, processing temperature, or time control.
Pub.: 23 Jun '17, Pinned: 28 Jun '17