Effect of CaCl2 on the stability and rheological properties of foams and high-sugar aerated systems produced by preheated egg white protein

Moderation-excess interactions of epigallocatechin gallate and CaCl2 modulate the gelation performance of egg white transparent gels

In this study, the moderation-excess interaction of epigallocatechin gallate (EGCG) and calcium ions (Ca2+) to the gelation performance of transparent egg white protein (EWP) gel (EWG) was explored. The oxidation of EGCG introduced a yellowish-brown EWG, whereas the weakening of Ca2+ ionic bonds caused a notable reduction in the hardness of EWG, from 120.67 g to 73.57 g. Achieving the optimal EGCG-to-Ca2+ ratio in EWG conferred enhanced water-holding capacity to 86.98%, while an excess of EGCG attributed to the creation of a three-dimensional structure within the void "walls". The elevated presence of EGCG influenced the ionic bonds and hydrophobic interactions, thereby presenting a moderate-excess relationship with sulfhydryl and disulfide bonds, β-sheet, and α-helical structures. Notably, EGCG reduced the digestibility of EWG to 50.06%, while concurrently fostering the creation of smaller particle sizes. This study provides a scientific basis for the controllable preparation and quality regulation of transparent EWG.

Studies on the Properties and Stability Mechanism of Double Emulsion Gels Prepared by Heat-Induced Aggregates of Egg White Protein-Oligosaccharides Glycosylation Products

Multiple emulsions can dissolve some substances with different properties, such as hydrophilicity and lipophilicity, into different phases. They play an important role in protection, controlled release and targeted release of the encapsulated substances. However, it's poor stability has always been one of the main problems restricting its application in the food industry. For this reason, a heat-induced aggregate (HIA) of Maillard graft product of isomalto-oligosaccharides (IMO), as well as egg white protein (EWP), was used as hydrophilic emulsifier to improve the stability of W1/O/W2 emulsions. Moreover, gelatin was added into the internal aqueous phase (W1) to construct W1/O/W2 emulsion-gels system. The encapsulation efficiency of HIA-stabilized W1/O/W2 emulsions remained nearly unaltered, dropping by only 0.86%, significantly outperforming the conjugates and physical mixture of IMO and EWP in terms of encapsulation stability. The emulsion-gels system was constructed by adding 5% gelatin in the W1, and had the highest EE% and good salt and heat stability after 30 days of storage. This experiment provides guidance for improving the stability of W1/O/W2 emulsions system and its application in the package delivery of functional substances in the food field.

Fabrication of bovine serum albumin nanofibrils: Physicochemical characteristics, emulsifying and foaming activities

Bovine serum albumin nanofibrils (BSNs) were fabricated under thermal treatment (85 °C) at acidic condition (pH 2.0) and the incubation time on the structural, and physicochemical characteristics were probed. The formation and development of BSNs have been detected and confirmed by Thioflavin T (ThT) fluorescence and circular dichroism (CD) measurements. The structural alterations of bovine serum albumin (BSA) have also been investigated using intrinsic fluorescence and Congo red (CGR) UV-vis spectroscopy. Atomic force microscopy (AFM) outcomes displayed the morphologies of BSNs at varied time, with a diameter of about 3 nm and a contour length of about 200 nm at 24 h. The apparent viscosities of BSNs at three different pH were in the following order: pH 3.0 > pH 5.0 > pH 7.0. Emulsifying and foaming properties of BSA were pronouncedly enhanced through fibrillation, which was highly correlated with the interfacial properties and structural characteristics. Highest EAI 54.2 m2/g was attained at 48 h and no pronounced alterations were observed for EAI at 24 h and 48 h. Maximum value of FC was obtained at 48 h for BSA. This study will provide some useful information in understanding the formation of BSNs and broaden their application in food systems as functional food ingredients.

Oleogel classification, physicochemical characterization methods, and typical cases of application in food: a review

The harmful effects of trans and saturated fatty acids have attracted worldwide attention. Edible oleogels, which can structure liquid oils, are promising healthy alternatives to traditional fats. Active research on oleogels is focused on the interaction between unsaturated oils with different fatty acid compositions and low molecular weight or polymer oleogels. The unique network structure inside oleogels has facilitated their application in candies, spreads, meat, and other products. However, the micro- and macro-properties, as well as the functional properties of oleogels vary by preparation method and the system composition. This review discusses the characteristics of oleogels, serving as a reference for the application of oleogels in food products. Specifically, it (i) classifies oleogels and explains the influence of gelling factors on their gelation, (ii) describes the methods for measuring the physicochemical properties of oleogels, and (iii) discusses the current applications of oleogels in food products.

Mechanistic insights into gel formation of egg-based yoghurt: The dynamic changes in physicochemical properties, microstructure, and intermolecular interactions during fermentation

This study aimed to elucidate the mechanism of acid-induced gelation in egg-based yoghurt by investigating the dynamic changes in physicochemical properties, texture, rheology, and microstructure of the gel during fermentation, combined with the role of intermolecular forces in gel formation. Results showed that protein aggregation and cross-linking increased as pH decreased during fermentation. Gel hardness increased with fermentation, eventually reaching 11.36 g, while maintaining low fracturability. Water holding capacity (WHC) decreased from 91.77% to 73.13% during fermentation. Rheological testing demonstrated a significant increase in viscosity and dynamic moduli (G' and G''), consistent with the observation of a more compact microstructure by scanning electron microscopy (SEM) and particle size analysis. Furthermore, dynamic changes of surface hydrophobicity, sulfhydryl content, and intermolecular forces suggested that hydrophobic interactions were likely the main driving force for gel formation, as well as that hydrophobic interactions and disulfide bonds played an important role in the maintenance and construction of the gel network structure. Although ionic bonds and hydrogen bonds also had an effect on the gel formation of egg-based yoghurt, their contributions were not significant. The study provided new insights for the development of novel egg-based fermentation foods and the research of acid-induced protein gels, and also contributed to the deep exploitation and utilization of poultry eggs.

Changes in structural, rheological, and gel properties of egg white protein induced by preheating in the dry state

The knowledge of fundamental rheological concepts is essential to understand the gelling process of egg white proteins (EWP), which can be used to further manipulate the gel performance with desired sensorial attributes. In this study, the rheological and gel properties of EWP as influenced by heating in the dry state were investigated. The structural changes in dry heated EWP (DEWP) were also characterized in terms of morphology, protein stability, and protein microenvironment. The results showed that moderate dry heating induced linear aggregation of DEWP and decreased the denaturation temperature (Td) and enthalpy of denaturation (ΔH). Furthermore, the cross-linking on protein surface led to nonpolar microenvironment of hydrophobic groups, which lays the foundation of improved gel properties. The specific outcomes include the increase in the G'max and the G''max values, k'/k'' values of DEWP dispersions, gel hardness and gumminess of DEWP gels and a decrease in gelation temperature of DEWP dispersions. However, few changes were found in the springiness and cohesiveness of the DEWP gels with increasing dry heating time. Notably, gels prepared with DEWP also had better digestibility. Overall, these results can provide theoretical basis for quality control and sensory evaluation of DEWP in the food industry.

Impact of alkaline electro-activation treatment on physicochemical and functional properties of sweet whey

The impact of alkaline electro-activation (EA) on the protein solubility, foaming, and emulsifying characteristics of whey was investigated. EA caused protein aggregation and conjugation. At low electric current and holding time, proteins aggregation through disulfide bonds was observed, whereas increasing currents and holding times caused proteins to conjugate with sugars such as lactose, lactulose and galactose. The EA process improved the protein solubility at the pH range of 4.0-7.0. Compared to untreated whey, which produced micron-sized and unstable emulsions at pH 3, whey samples treated under 750 mA and 24-48 h holding time formed nano-sized and stable emulsions at this pH. Furthermore, although both untreated and EA-whey produced stable emulsions at pH 7, those emulsions prepared with EA-whey had smaller particle size and were more stable against droplet flocculation. EA-treated whey tended to generate foams with significantly higher overrun and stability. The present study demonstrated that EA can enhance the functionality of whey.

pH-Dependent Binding Behavior of the α-Lactalbumin/Glycyrrhizic Acid Complex in Relation to Their Foaming Characteristics in Bulk

This work aimed to understand the relationships of the interaction mechanism and foaming characteristics of α-lactalbumin (α-La) and glycyrrhizic acid (GA) after acidic (pH 2.5) and neutral (pH 7.0) treatment. The critical aggregation concentration (CAC) of GA in the presence of α-La was 0.6 mM at pH 7.0, while it was 1.0 mM at pH 2.5. Also, in the presence of a GA concentration of 0-15.00 mM, more GA molecules combined onto the α-La surface at pH 2.5 than at pH 7.0, as evident from the binding isotherms. The turbidity and particle size of α-La/GA were greater in acidic solution than those under neutral conditions. This result could be interpreted by the formation of aggregates under higher GA concentration at pH 2.5. Meanwhile, the viscosity of the complex was higher at pH 2.5 than at pH 7.0 in the presence of 3.00-15.00 mM GA, as analyzed from the rheological properties. The foaming ability (FA) of α-La was significantly enhanced in the presence of 10.00 mM GA. Simultaneously, acidic solution could generate a more stable foaming system with a thicker film layer stabilized by the complex compared with neutral solution. These findings could be beneficial for developing a kind of acidic food-grade foaming agent.

Effects of ultrasound-assisted glycosylation on the interface and foaming characteristics of ovotransferrin

Ovotransferrin (OVT) is one of the major functional proteins in egg white protein. Most of the industry only paid attention the biological activity of OVT in iron supplement, antibacterial and other aspects, few reports were carried out on its processing characteristics such as foaming, interfacial behavior such as emulsification and foaming, which was an important processing functional attribute affecting its application scenario. In this study, the effects of ultrasound-assisted glycosylation on the interface and foaming characteristics of OVT were investigated. The results showed that proper ultrasonic treatment had a significant effect on the structure and physicochemical properties of OVT glycosylation products. When ultrasonic treatment lasted for 20 min, the grafting degree of OVT was 20.98%, the particle size decreased and the absolute value of potential increased. The foaming ability of OVT increased first and then decreased after ultrasonic-assisted glycosylation treatment. The foaming ability of OVT increased from 43.54% to 96.73% and the foaming stability increased from 68.92% to 89.19% after ultrasonic-assisted glycosylation treatment for 20 min. The experimental study effectively discovered the effect of ultrasound-assisted glycosylation on the foaming property of OVT, and would provide important technical references for expanding its application in food, biology, medicine and other fields.

Applications of Plant Polymer-Based Solid Foams: Current Trends in the Food Industry

Foams are a type of material of great importance, having an extensive range of applications due to a combination of several characteristics, such as ultra-low density, tunable porous architecture, and outstanding mechanical properties. The production of polymer foams worldwide is dominated by those based on synthetic polymers, which might be biodegradable or non-biodegradable. The latter is a great environmental concern and has become a major waste management problem. Foams derived from renewable resources have aroused the interest of researchers, solid foams made from plant polymers in particular. This review focuses on the development of plant polymer-based solid foams and their applications in the food industry over the last fifteen years, highlighting the relationship between their material and structural properties. The applications of these foams fall mainly into two categories: edible foams and packaging materials. Most plant polymers utilized for edible applications are protein-based, while starch and cellulose are commonly used to produce food packaging materials because of their ready availability and low cost. However, plant polymer-based solid foams exhibit some drawbacks related to their high water absorbency and poor mechanical properties. Most research has concentrated on improving these two physical properties, though few studies give a solid understanding and comprehension of the micro- to macrostructural modifications that would allow for the proper handling and design of foaming processes. There are, therefore, several challenges to be faced, the control of solid foam structural properties being the main one.

Effect of L-calcium lactate, zinc lactate, and ferric sodium EDTA on the physicochemical and functional properties of liquid whole egg

The study aimed to evaluate the physicochemical and functional properties of liquid whole egg (LWE) with L-calcium lactate (L-Ca), zinc lactate (L-Zn), and sodium ferric EDTA (NaFeEDTA), and to compare with NaCl addition to determine the application potential of these mineral supplements. Results showed that salts addition significantly influenced the foaming, emulsifying, and gelling properties of LWE, which was possible through affecting the pH, particle size, surface hydrophobicity, apparent viscosity, and solubility. The addition of all the four salts reduced pH but increased the d_4,3 diameter of LWE. Additionally, the addition of 200 mM L-Ca and 6 mM L-Zn significantly improved the emulsifying capacity by 41.73% and 13.6%, the foaming capacity by 26.57% and 10%, and the protein solubility by 13.89% and 12.70%, respectively. In the meantime, mineral supplements tend to produce lower hardness gel, especially with 25 mM L-Ca and 8 mM L-Zn, and the hardness was decreased from 2401.13 to 1138.29 and 1175.59 g, respectively. A relative decrease in hardness was desirable in gelled egg products. Moreover, the addition of NaCl and L-Ca showed a higher redness and yellowness, but the addition of NaFeEDTA showed an undesirable color in dark brown, which may be not accepted by the public. In summary, L-Ca and L-Zn had great potential for application in LWE, which was more appropriate than adding NaCl. This study provides a basis for improving the functional properties of LWE products in the future. PRACTICAL APPLICATION: The addition of L-Ca and L-Zn to liquid whole egg (LWE) could improve the foaming and emulsifying capacity of LWE as well as produce a lower hardness gel, which may be more conducive to the production of cake, custards, and meat products. Meantime, it is more in line with people's pursuit of a healthy diet.