The use of high hydrostatic pressure to generate folate-enriched extracts from the granule fraction of hen’s egg yolk

The effect of CaCl2 on water migration, rheological properties, aggregation behavior and protein structure in rapidly salted separated egg yolk plasma and granules

This research investigated the effects of CaCl2 on the aggregation behavior and protein structure of egg yolk plasma and granules after fast salting. The addition of CaCl2 to the salt solution decreased T23, D [4,3] and the absolute value of the zeta potential by 6.71%, 3.66%, and 3.15%, respectively, while increasing T22 by 15.85% in egg yolk plasma. Moreover, adding CaCl2 also increased the apparent viscosity and G' value of egg yolk plasma. On the other hand, the addition of CaCl2 decreased the T22, T23, D [4,3], and absolute value of the zeta potential of egg yolk granules by 56.53%, 6.71%, 6.02%, and 34.27%, respectively. Furthermore, the addition of CaCl2 increased the number of β-turns by 51.22%, whereas it decreased the number of β-sheets by 26.55% in egg yolk plasma protein. The α-helices, β-turns, and β-sheets of egg yolk granule protein decreased by 6.58%, 3.58%, and 6.96%, respectively. Additionally, the addition of CaCl2 can increase the degree of λmax redshift in egg yolk plasma and decrease the degree of λmax redshift in egg yolk granules. Overall, the addition of CaCl2 can change the aggregation mode of proteins in egg yolk plasma and granules, improving the quality of salted egg yolk products.

Development of plant-based whole egg analogs using emulsion technology

RuBisCO is a plant protein that can be derived from abundant and sustainable natural resources (such as duckweed), which can be used as both an emulsifying and gelling agent. Consequently, it has the potential to formulate emulsion gels that can be used for the development of plant-based replacements of whole eggs. In this study, we investigated the ability of RuBisCO-based emulsion gels to mimic the desirable properties of whole eggs. The emulsion gels contained 12.5 wt% RuBisCO and 10 wt% corn oil to mimic the macronutrient composition of real whole eggs. Initially, an oil-in-water emulsion was formed, which was then heated to convert it into an emulsion gel. The impact of oil droplet diameter (∼15, 1, and 0.2 μm) on the physicochemical properties of the emulsion gels was investigated. The lightness and hardness of the emulsion gels increased as the droplet size decreased, which meant that their appearance and texture could be modified by controlling droplet size. Different concentrations of curcumin (3, 6, and 9 mg/g oil) were incorporated into the emulsions using a pH-driven approach. The curcumin was used as a natural dual functional ingredient (colorant and nutraceutical). The yellow-orange color of curcumin allowed us to match the appearance of raw and cooked whole eggs. This study shows that whole egg analogs can be formulated using plant-based emulsion gels containing natural pigments.

Effect of high-hydrostatic pressure on the digestibility of egg yolk and granule

The impact of high hydrostatic pressure (HHP) on protein digestibility of egg yolk and egg yolk granule was evaluated by static in vitro digestion using the standardized INFOGEST 2.0 method. The degree of hydrolysis (DH) and the phospholipid content were determined during digestion, and the protein and peptide profiles were characterized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and reverse phase-high pressure liquid chromatography (RP-HPLC). The results showed that HHP induced protein aggregation in egg yolk and granule, mainly by disulfide bridges, which were not disrupted in the oral phase. Proteolysis during the gastric phase improved egg yolk and granule protein solubility, regardless of whether HHP was applied. However, the extent of the samples' digestibility was not affected, with DH values ranging from 15% to 20%. During the intestinal phase, the DH of egg yolk protein (∼40%) was higher than that of the granule (∼25%), probably due to the denser structure of the granule reducing the accessibility of intestinal enzymes. The DH, peptide, and protein profiles of control and HHP-treated egg yolk showed similar protein digestion behaviors for both gastric and intestinal phases. Among the different proteins, only the digestibility of β-phosvitin in HHP-treated granule was enhanced. Consequently, applying HHP to granules represents an interesting process that improves the digestibility of phosvitin with the potential to generate bioactive phosvitin-derived phosphopeptides. PRACTICAL APPLICATION: High hydrostatic pressure, mainly used as a preservation process, did not impair the nutritional quality of the egg yolk and granule proteins but improved the susceptibility of phosvitin (protein contained in egg yolk) proteolysis to produce bioactive phosphopeptides. Consequently, applying HHP to granules represents an interesting process that improves the digestibility of phosvitin.

Microstructural Changes in Vanilla planifolia Beans after Using High-Hydrostatic-Pressure Treatment in the Curing Process

During vanilla bean curing, the cell arrangement derived from the killing technique applied to start bean ripening is essential to obtain the characteristic aroma and flavor of vanilla. Hence, killing is an important step to release the enzymes and compounds required for vanillin production. In this work, high hydrostatic pressure (HHP) at 100-400 MPa for 5 min, using water at 7 °C as the pressure-transmitting medium, was applied as the killing method, and its effect on the microstructural changes in vanilla beans during different curing cycles (C0-C20) was evaluated and compared with that observed after scalding by using water at 100 °C for 8 s. Microstructural changes in the cross-sectioned beans were analyzed using a stereomicroscope (SM), confocal laser scanning microscopy (CLSM), and environmental scanning electron microscopy (ESEM). The vanilla beans were cross-sectioned and three main sectors were analyzed: the total, annular, and core. The morphometric descriptors, namely, area, Feret's diameter, and circularity, were quantified via digital image analysis (DIA), from which a shrinkage ratio was calculated. The results show that the total area in the beans presented a maximum decrease in the C16 of curing. The core area was most affected by the HHP treatment, mainly at 400 MPa, rather than scalding. CSLM observations revealed the autofluorescence of the compounds inside the beans. In conclusion, the use of microscopy techniques and DIA allowed us to determine the microstructural changes in the HHP-treated pods, which were found to be more numerous than those found in the scalded beans.

Physical Characteristics of Egg Yolk Granules and Effect on Their Functionality

Eggs are among the most nutritious foods in the world, a versatile ingredient in many food applications due to their functional attributes such as foaming, emulsifying, and coloring agents. Many studies have been reported on egg yolk fractionation and characterization in the last decade because of its nutritional and health benefits, especially egg yolk granules. This has led to the development of new food products and packaging materials. However, the influence of their physical characteristics during processing significantly impacts the functionality of yolk granules. In this overview, the egg yolk, the granule fraction's separation, fractionation, components, and molecular protein structure are first presented. Secondly, recent studies on egg yolk granules published over the past decade are discussed. Furthermore, the application of the granules in different industries and current specific scientific challenges are discussed. Finally, it simplifies the changes in the physical characteristics of the granules during different treatment methods and the impact on the functionalities of the resulting products in the food (emulsifiers, edible films), pharmaceutical, and health (encapsulation systems and biosensors) sectors.

Subcritical low temperature extraction of bioactive ingredients from foods and food by-products and its applications in the agro-food industry

Bioactive ingredients are part of the food chain and are responsible for numerous health benefits. Subcritical low temperature extraction has been employed to acquire bioactive ingredients because of its excellent properties, such as energy conservation, low temperature, elimination of residual solvent, and high extraction yield and quality. This review aims to provide a clear picture of the basics of subcritical-temperature extraction, its bioactive ingredient extraction efficiency, and possible applications in the agro-food industry. This review suggested that the extraction temperature, time, co-solvents, solid-fluid ratio, and pressure impacted the extraction efficiency of bioactive ingredients from foods and food by-products. Subcritical solvents are appropriate for extracting low polar ingredients, while the inclusion of co-solvents could extract medium and high polar substances. Bioactive ingredients from foods and food by-products can be used as antioxidants, colorants, and nutritional supplements. Additionally, this technology could remove pesticide residues in tea, concentrate edible proteins, and reduce cigarette tar. A new trend toward using subcritical low temperature extraction in extracting bioactive ingredients will acquire momentum.

Impact of Ultra-High Pressure Homogenization on the Structural Properties of Egg Yolk Granule

Ultra-high pressure homogenization (UHPH) is a promising method for destabilizing and potentially improving the techno-functionality of the egg yolk granule. This study’s objectives were to determine the impact of pressure level (50, 175 and 300 MPa) and number of passes (1 and 4) on the physico-chemical and structural properties of egg yolk granule and its subsequent fractions. UHPH induced restructuration of the granule through the formation of a large protein network, without impacting the proximate composition and protein profile in a single pass of up to 300 MPa. In addition, UHPH reduced the particle size distribution up to 175 MPa, to eventually form larger particles through enhanced protein–protein interactions at 300 MPa. Phosvitin, apovitellenin and apolipoprotein-B were specifically involved in these interactions. Overall, egg yolk granule remains highly stable during UHPH treatment. However, more investigations are needed to characterize the resulting protein network and to evaluate the techno-functional properties of UHPH-treated granule.

Degradation of 5-methyltetrahydrofolate in model and egg yolk systems and strategies for its stabilization

In this study, the stability of 5-methyltetrahydrofolate (5-MTHF) in the model system and folate-enriched egg yolk and strategies for 5-MTHF stabilization were investigated. The oxygen, temperature and light affect the stability of 5-MTHF in the model system, among which oxygen is the main factor. In thermal pasteurization and spray-drying with normal air media, 5-MTHF is sensitive to oxidation, with the retention rate of blank group only reaching 74.96% ± 1.28%. The addition of vitamin C or vitamin E can protect 5-MTHF in egg yolk from degradation and the latter has a better protective effect. By adding 0.2% (w/v) vitamin E to egg yolk liquid, the retention rate of 5-MTHF during thermal pasteurization and spray-drying with normal air media were 94.16% ± 0.48% and 84.80% ± 0.82% respectively. Additionally, the spray-drying technique with inert gas media (N₂) was also an effective method to improve the stability of the 5-MTHF in egg yolk. Our study explored the factors affecting the stability of 5-MTHF in both model systems and egg yolk liquid and provided effective strategies for the protection of 5-MTHF during the processing of egg.

Depolymerization of chicken egg yolk granules induced by high-intensity ultrasound

The effects of high-intensity ultrasound (HIU) treatment-induced depolymerization of chicken egg yolk granules were investigated. The results showed that the yolk granules were depolymerized after HIU treatment, and the average particle size was significantly reduced from 289.4 nm (untreated) to 181.4 nm (270-W HIU treatment). All contents of dry matter, protein, calcium and phosphorus in the supernatant of the HIU-treated yolk granule solution increased, which suggests that HIU treatment increases the dissolution of yolk granule components. Spectroscopic analysis showed that HIU treatment increased the polarity of the microenvironment and enhanced the hydrogen bond force of yolk granules. These changes induced by HIU treatment collectively enhanced the zeta potential, decreased the free sulfhydryl group content, and slightly improved the emulsifying activity index of yolk granules. The present study reveals the depolymerization effect of HIU treatment on egg yolk granules and can inspire new potential applications of egg yolk granules.

Gelation behavior of egg yolk under physical and chemical induction: A review

Gelation is one of the most important functional properties of egg yolk. High content and rich variety of protein and lipid in egg yolk are the material basis of gel formation. The natural structure of proteins in egg yolk is unfolded under treatments such as heat, alkali, salt, etc., thus causing the interactions between protein-protein and protein-lipid and forming the gel. Under different methods of induction, egg yolk is solidified to form different three-dimensional network structures. Different inducing methods exhibit different gel formation mechanisms. In this paper, the gelation behavior of egg yolk and its internal molecular agglomeration mechanism induced by heat, alkali, salt, freezing, high pressure, and salt-heating synergy were reviewed to provide a reference for further studies on the formation mechanisms and product development of egg yolk gel.

A novel electrochemical paper sensor for low-cost detection of 5-methyltetrahydrofolate in egg yolk

An electrochemical deposition method was used to fabricate a gold nanoflower (AuNF) and carbon nanoparticle (CNP) modified carbon paper (CP) sensor (AuNFs-CNPs/CP) for the low-cost detection of 5-methyltetrahydrofolate (5-mTHF) in egg yolk. AuNF morphology and structures were characterized by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), revealing nanoflower sizes in the 50 to 200 nm range. AuNFs formed on the sensor were in the Au⁰. We evaluated 5-mTHF assay performance using cyclic voltammetry, differential pulse voltammetry and chronoamperometry. The AuNFs-CNPs/CP sensor detected 5-mTHF concentrations in the ranges from 1 to 5 mg L^-1 and 1-20 μg L^-1, with an excellent limit of detection of 1 μg L^-1 and good selectivity toward 5-mTHF, when compared to other potentially interfering molecules in samples. The AuNFs-CNPs/CP sensor was also used to detect 5-mTHF in folate-rich, and was found to be twice than that of ordinary egg yolk.

High hydrostatic pressure induced extraction and selective transfer of β-phosvitin from the egg yolk granule to plasma fractions

Egg yolk phosvitin is of particular interest due to its functional and biological properties. Recently, it was demonstrated that high hydrostatic pressure (HHP) (400 MPa for 5 min) induced the transfer of folic acid and phosvitin from the egg yolk granule to the plasma fraction. A granule fraction (G_in) produced by egg yolk centrifugation was pressure-treated at 400 and 600 MPa for 5 and 10 min, and centrifuged to generate granule fractions (G_P1 to G_P4) and plasmas (P_P1 to P_P4). Iron and phosphorus contents were also increased in P_P1 to P_P4 fractions, confirming the transfer of phosvitins from pressure-treated granule to plasma. Pressurization drastically improved phosvitin recovery in P_P fractions, specifically at 600 MPa for 10 min, which had the highest value of phosvitin/100 mg of dry plasma at 33.3 ± 4.39 mg. Consequently, HHP represents an alternative approach for phosvitin transfer and recovery in the egg yolk soluble fraction.

Effects of high-intensity ultrasonic (HIU) treatment on the functional properties and assemblage structure of egg yolk

The effects of high-intensity ultrasonic (HIU) treatment on the functional properties of egg yolk were studied in the present work. After HIU treatment, the emulsifying, foaming and gel properties of the egg yolk solution significantly increased, but the foam stability decreased. SDS-PAGE results showed that there was no obvious change in the protein bands of egg yolk, indicating that the yolk proteins did not undergo covalent crosslinking or degradation. HIU treatment enhanced the zeta potential of egg yolk components in solution and increased the free sulfhydryl content of egg yolk proteins. Moreover, the particle size distribution of egg yolk components in solution changed markedly, and these changes demonstrated that HIU treatment caused the aggregation of yolk low-density lipoprotein and the partial dissociation of yolk granules. These results revealed that HIU treatment could change the aggregation of yolk components, which in turn could influence the solution characteristics of egg yolk, finally resulting in changes to the functional properties of egg yolk.

How Can the Value and Use of Egg Yolk Be Increased?

The major driving force for the egg consumption in the United States over the past few decades was processed egg. However, the consumption of egg through the processed egg reached the plateau in recent years because of the imbalance in the demands between the egg white and yolk products. The consumer demands for egg white products are very high while those for the egg yolk, the co-product of dried egg white, are low because of the negative perceptions on egg yolk. Two key approaches that can be used to increase the value and use of egg yolk are: (1) developing new commodity products by fractionating egg yolk and apply them in various food processing, and (2) separating functional proteins and lipids from yolk and use them as is or further develop functional peptides and functional lipids and use them as pharmaceutical, nutraceutical, and cosmeceutical agents. These approaches can diversify the use of egg yolk, which eventually will help increase the consumption of egg. This review (1) discusses the current use of egg yolk products and the development of new functional commodity products from egg yolk, (2) review the important functional components in egg yolk and overview the current separation methods and their applications, (3) discuss the production of functional peptides and lipids using the separated egg proteins and lipids, and (4) suggest the future directions for the best use of egg yolk components. Development of scale-up production methods, which is vital for the practical applications, is discussed when appropriate.