Egg White Gel Research Articles

Effects of Modified Oil Palm Kernel Expeller Fiber Enhanced via Enzymolysis Combined with Hydroxypropylation or Crosslinking on the Properties of Heat-Induced Egg White Protein Gel

Due to its poor hydration properties, oil palm kernel expeller dietary fiber (OPKEDF) is rarely used in the food industry, especially in hydrogels, despite its advantages of high availability and low cost. To address this situation, the effects of enzymolysis combined with hydroxypropylation or crosslinking on the structure and hydration properties of OPKEDF were investigated, and the impact of these modified OPKEDFs on the properties of egg white protein gel (EWPG) was studied. Enzymolysis combined with hydroxypropylation or phosphate crosslinking improved the soluble fiber content (5.25–7.79 g/100 g), water-retention and expansion abilities of OPKEDF (p < 0.05). The addition of unmodified OPKEDF or modified OPKEDF increased the random coil content of EWPG and increased the density of its microstructure. Moreover, enzymolysis combined with hydroxypropylation or crosslinking enhanced the effect of OPKEDF on the properties of EWPG, including improvements in its water-retention ability, pH, hardness (from 97.96 to 195.00 g), chewiness (from 78.65 to 147.39 g), and gumminess (from 84.63 to 152.27) and a reduction in its transparency (p < 0.05). Additionally, OPKEDF and enzymolysis and hydroxypropylated OPKEDF increased the resilience (0.297 to 0.359), but OPKEDF treated via enzymolysis and crosslinking reduced it. Therefore, OPKEDF modified by means of enzymolysis in combination with hydroxypropylation or crosslinking improved the gel properties of EWPG. However, further work is required to determine the effects of these modifications on the nutritional profile, scalability, and economic feasibility of OPKEDF and egg white gel.

Lactic acid bacteria fermentation-induced egg white protein structure deformation influencing gelling properties, with membrane concentration as a strategy to improve texture.

Egg white (EW), a rich protein source, holds promise for creating a high-protein, low-fat gel product. However, browning issues during heating and sterilization have hindered its wider application. In this study, lactic acid bacteria fermentation was employed to eliminate reducing sugar in EW, and its impact on the molecular structure and gelling properties was explored. The results revealed that fermentation would trigger protein structural unfolding and aggregation, evident from higher fluorescence intensity and enlarged protein particle diameters, resulting in the decrease in gelling hardness. In comparison, Streptococcus thermophilus-fermented EW (under 6×108CFU/mL incubation rate, fermented for 6h) exhibited the highest gel hardness, ascribed to the relatively weaker structure transformation, with high water holding capacity and stronger intermolecular hydrophobic interaction. To further enhance the gelling properties of fermented EW, membrane concentration treatment was applied, exhibiting superior characteristics in appearance, aroma, and taste. In summary, lactic acid bacteria fermentation and concentration are feasible solutions to improve appearance and texture of EW gels simultaneously. The research findings offer eco-friendly and practical strategies for enhancing the quality of EW gels, providing valuable theoretical insights for the development of innovative, texture-rich, and healthy nutritional foods.

The regulation mechanism of ultrasonic treatment on alkali-induced egg white protein gel: Structure, molecular characteristics and intermolecular forces distribution

Egg white protein can be cross-linked to form a gel under alkali induction, which is typically represented by the preserved eggs from Chinese traditional food. The effects of ultrasonic at different intensities (50 W, 100 W, 200 W, and 300 W) on alkali-induced egg white protein (EWP) gel were investigated. The gel strength rose significantly by 26.08 % upon treatment with 50 W, but it gradually declined as the intensity increased. Meanwhile, the structure unfolding and molecular aggregation of EWP were affected by ultrasonic. Compared with 300 W, 50 W could enhance surface hydrophobicity and decrease total free sulfhydryl group content more during gel formation. Selective solubility experiment confirmed that ultrasonic reduced the formation of ionic bonds, which slightly slowed down the initial gelation. Simultaneously, 50 W promoted the formation of more disulfide bonds, which helped to improve the strength of the final gel, while the same effect was not observed at 300 W. In general, moderate ultrasonic can effectively improve the alkali-induced EWP gel properties, which provides theoretical support for developing high quality preserved eggs and protein gel foods.

Millet Bran Dietary Fibers Modified by Heating and Enzymolysis Combined with Carboxymethylation, Acetylation, or Crosslinking: Influences on Properties of Heat-Induced Egg White Protein Gel.

Applications of millet bran dietary fiber (MBDF) in the food industry are limited by its poor hydration properties. Herein, MBDF was modified by heating, xylanase and cellulase treatment separately combined with carboxymethylation, acetylation, and phosphate crosslinking, and the effects of the modified MBDFs on heat-induced egg white protein gel (H-EWG) were studied. The results showed that three composite modifications, especially heating and dual enzymolysis combined with carboxymethylation, increased the surface area, soluble fiber content, and hydration properties of MBDF (p < 0.05). MBDF and the modified MBDFs all made the microstructure of H-EWG denser and decreased its α-helix content. Three composite modifications, especially heating and dual enzymolysis combined with carboxymethylation, enhanced the improving effect of MBDF on the WRA (from 24.89 to 35.53 g/g), pH, hardness (from 139.93 to 323.20 g), chewiness, and gumminess of H-EWPG, and enhanced the gastric stability at 3-5 g/100 g. MBDFs modified with heating and dual enzymolysis combined with acetylation or crosslinking were more effective in increasing the antioxidant activity of the gastrointestinal hydrolysates of H-EWG than MBDF (p < 0.05). Overall, heating, xylanase and cellulase treatment separately combined with carboxymethylation, acetylation and crosslinking can enhance the hydration properties and the improving effect of millet bran fibers on H-EWG properties.

Eco-friendly one-step egg white gel preparation for sensitive detection of 13 trichothecenes in oats using UHPLC-MS/MS.

Oat products have gained widespread recognition as a health food due to their rich and balanced nutritional profile and convenience. However, the unique matrix composition of oats, which differs significantly from other cereals, presents specific challenges for mycotoxin analysis. This study presents an ultrahigh-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method enhanced with an innovative egg white gel pretreatment for the simultaneous analysis of 13 regulated and unregulated trichothecenes in oats. The method demonstrated excellent performance with high accuracy (> 87.5%), repeatability (< 5.7%), and reproducibility (< 8.1%). Analysis of 100 commercial oat products revealed a concerning detection rate (78%) for at least one of the 11 trichothecenes investigated. Notably, deoxynivalenol, exceeding the standard limit in 2% of samples, exhibited the highest detection rate (62%). Additionally, concerning co-occurrence patterns and positive correlations were observed, highlighting potential synergistic effects. The first-time detection of unregulated mycotoxins (T-2 triol, 4,15-diacetoxyscirpenol, 15-acetoxyscirpenol, and neosolaniol) underscores the need for comprehensive monitoring. This method, while developed for oats, shows potential for broader application to other cereals, though further investigation and confirmation are necessary. These findings suggest a potentially underestimated risk of trichothecenes in oats, necessitating continuous monitoring to ensure consumer safety.

Formation mechanism and stability of egg white fluid gels under ultrahigh-pressure homogenization pretreatment and synergistic heating effect

The thermal sterilization process of protein beverages inevitably leads to the formation of insoluble thermal aggregates, greatly reducing the texture and taste of protein beverages. In this study, homogenized egg white (HEW) was obtained by ultrahigh-high-pressure (UHP) homogenization pretreatment of egg white (EW), and then a special egg white fluid gel (EWFG) was prepared by water bath heating. The results showed that the optimal conditions for preparing EWFG were three cycles at 20 MPa homogenizing pressure and heating in a water bath at 72℃ for 10 min. Under these conditions, the EWFG was a milky-white homogeneous liquid with an average particle size of about 560 nm. Measurements of the physicochemical properties of HEW and EWFG showed that the UHP homogenization treatment reduced the viscosity of HEW, decreased the particle size of protein aggregates, and increased the zeta potential, which altered the interactions of proteins during the subsequent heating process and facilitated the formation of homogeneous and dispersed EWFG. EWFG showed good stability at pH 6–10 and in low-concentration saline and medium-concentration sucrose solutions. The EWFG obtained by the present treatment is more suitable for factory-scale production and has great potential for protein beverage applications.

Crucial effect of ovomucin on alkali-induced egg white gel formation: Properties, structure and facilitation mechanism

Alkali-induced preserved egg gel formation is a dynamic process that involves complex protein changes. Ovomucin (OVM) is closely associated with the gel properties of egg white. In this study, the effect of OVM in alkali-induced egg white gel (AEWG) formation was investigated. The results suggested that OVM reduced the gel formation time by 15 %. The mechanical properties of the fully formed gel were also improved by OVM. Specifically, OVM increased the storage modulus (G′) of the gel by 1.5-fold, while the hardness significantly increased from 78.90 ± 4.24 g to 99.80 ± 9.23 g. Low-field nuclear magnetic resonance (LF-NMR) demonstrated that OVM significantly shortened T23 relaxation time and reduced the water mobility, thus increasing the water holding capacity (WHC). Meanwhile, the presence of OVM resulted in a more homogeneous and denser microscopic morphology of the gel. Selective solubility experiments revealed that disulfide bonds are the primary force in gel formation. OVM promoted the formation of more disulfide bonds, which increased the strength and stability of the gel network. Overall, this research proved OVM plays a critical role in the performance improvement of AEWG, which provides a new insight into the quality control of preserved egg and protein gel foods.

Alkali‐induced aggregation behaviour of tea polyphenols and its gel strengthening mechanism to alkali‐induced egg white

SummaryThe effect of black and green tea extracts with different alkali induction degrees on gel properties of alkali‐induced egg white gels (EWGs) was evaluated. Results indicate that, with the increase in alkali induction time, the concentration of soluble polyphenols gradually decreases while their relative polymerisation degree increases, especially for black tea polyphenols. The addition of tea extracts, especially induced by alkaline treatment for 6, 12, and 24 h, can promote the coagulation and browning and inhibit the ‘alkali injury liquefaction’ of alkali‐induced EWGs. Additionally, under alkali‐induced conditions, polyphenols in tea, especially black tea, can enhance the textural properties and thermal stability of alkali‐induced EWGs, this enhancement reaches its peak at 12 h of alkali induction and is consistent with protein secondary structure and interaction forces results. This research provides theoretical support for selection and induction of tea in high‐gel‐strength preserved eggs and other alkali‐induced protein gel food processing.

Characterization and mechanism of thermally induced tea polyphenols and egg white proteins gel system and its 3D printing

In this study, the effect of tea polyphenols (TP) on the properties of thermally induced egg white protein (EWP) gel system was investigated by rheological, particle size, ζ potential, fluorescence spectroscopy, FT-IR, DSC, LF-NMR, SEM, and the suitability of EWP-TP for 3D food printing technology was assessed. The results showed that with the addition of TP, the interaction of TP with EWP led to fluorescence quenching and a blue shift of the maximum emission wavelength. The decrease in the polarity of the microenvironment around the EWP increased the hydrophobicity and altered the peptide chain structure with the addition of TP. Compared with the EWP gel system, the structure of the EWP-TP gel system had higher thermal stability and lower water content, and the microstructure of the network was more homogeneous, dense and smooth. The addition of TP significantly improved the stability of the EWP-TP gel system, the absolute value of the potential of the EWP gel system was 16.73 ± 0.91 nm, which was significantly lower than the EWP-TP gel system (P < 0.05). Besides, the 3D printing gel system prepared by EWP-TP and polysaccharide had the smoothest printing lines, more stable structure, and the best printing effect at the 0.12 g TP addition.

The pH dependent structural and viscoelastic behavior of Ovomucin-Complex isolated from egg white under alkaline conditions

Ovomucin-Complex (OVM) is responsible for providing the natural gel-like properties of egg white, especially in alkali-induced egg white gels. In this study, OVM was modified by alkaline to produce gel-type materials. The structure, physicochemical and viscoelastic properties of OVMs under different pH (7–12) were probed using FTIR, HPLC, SEM, CLSM and rheometer. The results of rheological measurements in linear viscoelastic region revealed that alkaline modified OVMs exhibited a soft viscoelastic gel in alkaline conditions, with the transition occurring near pH 8, compared with a viscoelastic solution at neutral pH. In addition to the pH-dependent gelation behavior of OVMs, further rheological studies under nonlinear deformations reveal shear thinning and an apparent yield stress, which were also highly affected by pH. The results from HPLC and molecular interactions suggest that the alkaline modification led to the depolymerization of OVMs in alkaline conditions, enhancing the formation of intermolecular disulfide bonds, electrostatic force and hydrophobic interactions. The differences in these mechanical properties were also reflected in the OVM structure. The SEM and CLSM images demonstrated that the arrangement of gel pores under pH 10 conditions is denser and well-distributed than those under other conditions. The FTIR results verified that alkaline modification leads to the decreased content of β-sheet. Nevertheless, prolonged exposure to pH 12.0 resulted in a gradual liquefaction of the gel due to increased electrostatic repulsion and surface hydrophobicity, as well as the reduced disulfide bond and an increase in the disordered structure. These findings provide a novel insight for the development of mucin gel foods.

Egg white fermentation by lactic acid bacteria: Effects on gel characteristics and preliminary investigation of suitable genera

There were few researches to investigate the suitable lactic acid bacteria (LAB) genera for long time fermentation of on egg white (EW). This study aimed to investigate effect of complex LAB fermentation on protein structure and gel properties of EW, and identify LAB genera suitable for EW environment. Therefore, high-throughput sequencing, fluorescence spectroscopy, texture profile analysis, and scanning electron microscopy (SEM) were performed. Sequencing results showed Bifidobacterium and Lactiplantibacillus were the main LAB genera, suggesting their potential to ferment EW for long time. During fermentation, the pH decreased from 9.20 to 8.91 in EW, and from 9.25 to 8.82 in diluted egg white (DEW). Surface hydrophobicity of EW and DEW protein increased from 6.60% to 11.70% and 3.18%–30.98% (p < 0.05), respectively. Gel hardness and springiness of fermented DEW in the presence of glucose increased significantly 16.64% and 2.46% at 12 h, 18.02% and 1.94% at 24 h, respectively. SEM results showed that protein aggregates distributed more evenly in dilution and glucose supplemented EW gel. The lower pH, higher surface hydrophobicity, and better texture characteristics indicated that the supplement of glucose and the dilution of EW were helpful for the progress of fermentation. In conclusion, Bifidobacterium and Lactiplantibacillus genera were seemed to adapt well in EW, and the dilution as well as glucose supplement was verified effectively to promote the LAB fermentation process. These findings can serve as a reference for the development of fermented EW products and provide guidance for further processing of eggs.

Chicken Egg White Gels: Fabrication, Modification, and Applications in Foods and Oral Nutraceutical Delivery.

Chicken egg white (EW) proteins possess various useful techno-functionalities, including foaming, gelling or coagulating, and emulsifying. The gelling property is one of the most important functionalities of EW proteins, affecting their versatile applications in the food and pharmaceutical industries. However, it is challenging to develop high-quality gelled foods and innovative nutraceutical supplements using native EW and its proteins. This review describes the gelling properties of EW proteins. It discusses the development and action mechanism of the physical, chemical, and biological methods and exogenous substances used in the modification of EW gels. Two main applications of EW gels, i.e., gelling agents in foods and gel-type carriers for nutraceutical delivery, are systematically summarized and discussed. In addition, the research and technological gaps between modified EW gels and their applications are highlighted. By reviewing the new modification strategies and application trends of EW gels, this paper provides insights into the development of EW gel-derived products with new and functional features.

Study on the gelling properties of egg white/surfactant system by different heating intensities

The aim of this study was to elucidate the different effects and difference mechanism of gelling properties among egg white (EW) treated with different heating intensities and the composite addition of rhamnolipid and soybean lecithin. Particle size analyzer, potentiometric analyzer, surface hydrophobicity method, and Fourier transform infrared spectroscopy techniques were used to determine the physicochemical properties and molecular structure, respectively. Low-field nuclear magnetic resonance, magnetic resonance imaging, texture profile analysis, and scanning electron microscopy techniques were used to analyze the gelling properties and gel structure, respectively. And we illuminate the different mechanisms in the gelling properties of the EW with various treatments and key internal factors that play important roles in improving gelling properties by establishing the link between the gelling properties and relevant characteristics by mixed effects model and visual network analysis. The results indicate raising the content of rhamnolipid decreased the migration of immobilized water in the EW gel and the free water content. At the heating intensities of 55 °C/3.5, 65 °C/2.5, and 67 °C/1.5 min, with an increase in rhamnolipid, the gel's cohesiveness, gumminess, and chewiness gradually increased. The mixed effects model indicated that heating intensities and composite ratios have a 2-way interaction on zeta potential, the relaxation time of bound water (T21), the content of bound water (P21), the content of immobilized water (P22), and fractal dimension (df) attributes (P < 0.05). The visual network analysis showed that the protein solubility, the relaxation time of immobilized water (T22), surface hydrophobicity, zeta potential, average particle size (d43) and the relaxation time of free water (T23) are critical contributors to the different gelling properties of EW subjected to various treatments and the improvement of gelling properties. This study will provide theoretical guidance for the development of egg white products and the expansion of egg white's application scope in the egg product processing industry.

Research note: Preparation and stability of egg white fluidic gel induced by ultrasonic pretreatment

Ultrasound-induced egg white fluidic gels (UEFG) were prepared through ultrasonic pretreatment followed by subsequent heating. The optimal preparation parameters for UEFG were: ultrasonic power density between 0.2 to 0.8 W/mL, ultrasonic treatment time surpassing 150 s, heating temperature within 70 to 76°C, and heating time under 16 min. The prepared UEFG is a milky white solution with a viscosity lower than that of fresh egg white, and displayed a particle size distribution primarily between 100 and 1,200 nm. Stability assessments conducted over 28 d at 4°C revealed that UEFG remained stable at pH 6-10, with exceptional stability from pH 8 to 10, while it is less stable in highly acidic (pH 2-4) or basic environments (pH 12). The UEFG also showed commendable stability in the presence of salt and sucrose solutions. We report a simple and novel method for preparing UEFG with good flowability after heating treatment. The UEFG has broad applications in the food industry, such as precooked egg white powder, high protein beverages, composite dairy products, etc.

Effect of Addition of Tannin Extract from Underutilized Resources on Allergenic Proteins, Color and Textural Properties of Egg White Gels.

Tannins, present in numerous plants, exhibit a binding affinity for proteins. In this study, we aimed to exploit this property to reduce the concentration of allergenic egg white proteins. Tannins were extracted, using hot water, from the lyophilized powder of underutilized resources, such as chestnut inner skin (CIS), young persimmon fruit (YPF), and bayberry leaves (BBLs). These extracts were then incorporated into an egg white solution (EWS) to generate an egg white gel (EWG). Allergen reduction efficacy was assessed using electrophoresis and ELISA. Our findings revealed a substantial reduction in allergenic proteins across all EWGs containing a 50% tannin extract. Notably, CIS and BBL exhibited exceptional efficacy in reducing low allergen levels. The addition of tannin extract resulted in an increase in the total polyphenol content of the EWG, with the order of effectiveness being CIS > YPF > BBL. Minimal color alteration was observed in the BBL-infused EWG compared to the other sources. Additionally, the introduction of tannin extract heightened the hardness stress, with BBL demonstrating the most significant effect, followed by CIS and YPF. In conclusion, incorporating tannin extract during EWG preparation was found to decrease the concentration of allergenic proteins while enhancing antioxidant properties and hardness stress, with BBL being particularly effective in preventing color changes in EWG.

Multi-staged temperature control of the gelling properties and flavor quality of preserved eggs

The gelling properties and flavor quality of preserved eggs are affected by temperature reached during pickling. In response, this study investigates the effects of different temperature-controlled techniques on the gelling properties and flavor quality of preserved eggs. The results show that compared with an overall constant temperature and a two-stage temperature-controlled technique, the P-12–18–30 °C three-stage temperature-controlled pickling model produced the best texture properties of the preserved egg white gel, as further verified by LF NMR and SEM analysis. The results of amino acid analysis also show that the taste intensity of free amino acids in the P-12–18–30 °C group was significantly increased, especially for umami amino acids. In addition, the results of the electronic noise show that the volatile components of preserved eggs subjected to different temperature-controlled pickling techniques were similar, mainly consisting of short-chain alkanes; alcohols, aldehydes, ketones, and some aromatic compounds; long-chain alkane aliphatic groups; and inorganic sulfides, and there was no significant difference in the content of each flavor substance. In conclusion, this study offers theoretical basis for temperature-controlled pickling of preserved egg with better gel quality.

Effects of Polyphenols in Different Teas on Physicochemical Characteristics of Egg White Protein Gel During Tea Eggs Making

Effects of Polyphenols in Different Teas on Physicochemical Characteristics of Egg White Protein Gel During Tea Eggs Making

Enhancement of emulsion pH stability by Ca2+ modulation: A novel approach for preparing egg white protein fibril cold emulsion gels

Egg white, a crucial ingredient in bulk food production with limited emulsifying properties, can be significantly improved by fibrillation modification. However, resulting emulsions may exhibit instability at critical food processing pH values. In this study, the egg white protein fibril (EWPF) emulsion gel was constructed by Ca2+, and the stability enhancement mechanism under different EWPF and Ca2+ concentrations was investigated. The results showed that higher EWPF concentrations led to improved stabilization of the oil-water interface. At 60 mg/mL EWPF concentration, water loss decreased by 13.86% and oil loss by 35.79%, while the firmness and viscosity of the emulsion gel system were enhanced. The ζ-potential was reduced by 67.98% and the ionic bond content was increased by 22 times with the addition of Ca2+, the droplets showed a uniform cross-linked structure, and the stability and plasticity of the system were improved. By adjusting EWPF concentration to 40 mg/mL and Ca2+ concentration to 30 mM, pH stability of the system was also enhanced. This study provided a reference for the high-value utilization of egg white and a possibility for the application of EWPF in food processing, such as low-fat foods.

Heat-induced gelation of egg white proteins depending on heating temperature: Insights into protein structure and digestive behaviors in the elderly in vitro digestion model

This study investigated the effects of heating temperature of egg white gels (EWGs) on the digestive characteristics by heating egg white (EW) to reach 75 °C (EWG-75) and 95 °C (EWG-95). The gel protein structure showed a decrease in the maximum tryptophan fluorescence intensity and a significant increase in the surface hydrophobicity of EWGs compared to EW (P < 0.05). The total and reactive free sulfhydryl groups were higher in the EWGs than in the EW (P < 0.05). While the proportions of α-helical and β-sheet structures remained similar in EW and EWG-75 (P > 0.05), EWG-95 exhibited a notable decrease in α-helix content (P < 0.05) and an increase in β-sheet content (P < 0.05). Furthermore, EWG-95 displayed higher hardness and cohesiveness than EWG-75 (P < 0.05). In the adult and elderly in vitro digestion models, EWG-95 exhibited the highest protein digestibility (50.44 % and 54.65 % in the models of elderly and adult subjects, respectively) after GI digestion (P < 0.05), followed by EWG-75 and EW. The electrophoretogram of the digesta revealed more intense protein bands in the elderly digestion model, particularly in the gastric digesta of EW, indicating slower digestion compared to the adult model. Therefore, EW should be appropriately heated before consumption, especially for elderly individuals, to facilitate efficient protein digestion and absorption.

Tailoring an egg white protein double network emulsion gel as a novel fat substitute for improving freeze-thaw stability of minced meat gel

This work aimed to investigate the effect of double network emulsion gel (DNEG) as a substitute for pork back fat (PBF) on the freeze-thaw stability of minced meat gel (MMG). We used slow acidification with glucono-δ-lactone (GDL) to induce egg white protein (EWP) gelation, while CaCO3 was affected by acidification to release Ca2+ to cross-link sodium alginate (SA), resulting in the gradual formation of DNEG networks. The MMG prepared using DNEG substitute for PBF had fine hardness and color after 5 freeze-thaw cycles (FTCs). This was due to the excellent plasticity of DNEG, which made it more capable of filling the voids of minced meat products, thus reducing the space for ice crystal growth. As a result, MMG prepared with DNEG could pass through the maximum ice crystal formation zone faster and avoid damage due to the formation of larger ice crystals. Notably, DNEG provided a barrier for the migration of immobilized water to bulk water in the sample. After several freeze-thaw treatments, the water holding capacity of samples prepared with DNEG decreased significantly slower, which slowed down the oxidation and decomposition of meat proteins. In summary, this study revealed the role of fat substitute DNEG as a favorable filling material for improving the freeze-thaw stability of minced meat products, and provided a technical reference for the development of healthy and storable meat products.