No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Covalent conjugation of bovine serum album and sugar beet pectin through Maillard reaction/laccase catalysis to improve the emulsifying properties
Abstract
The study aims at improving the emulsifying stability of sugar beet pectin (SBP) by covalent coupling of proteins to polysaccharide. Laccase and Maillard reaction in a controlled dry state condition (85 °C, 79% relative humidity for 5 h) were adopted to kinetically control the formation of hetero-covalent linkages between SBP and bovine serum albumin (BSA). The formation of BSA-SBP conjugates was confirmed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and peak position using gel permeation chromatography, multi angle laser light scattering and refractive index. The decrease rates of tyrosine and ferulic acid contents were positively correlated with the laccase dosage. The optimum condition of laccase catalysis was 500 U/g sample powder at a BSA/SBP weight ratio of 0.25. Measurements of particle size distribution and average particle size showed that emulsifying performance of BSA-SBP conjugation improved greatly compared with individual BSA and SBP. Emulsions stabilized by BSA-SBP conjugates were less susceptible to environmental stresses, such as at the present of salts, low pH, thermal and freeze-thaw treatments. Covalently conjugated SBP and proteins has greatly potential applications as novel emulsifier in food industry.
... Considering the high values of the zeta potential and the physical instability of nanoemulsions during storage, it can be concluded that additional factors (e.g., adsorption affinity, viscosity, interfacial film characteristics, etc.) other than the electrostatic repulsion among the dispersed droplets (i.e., zeta potential) are required for the long term stability of nanoemulsions. Chen et al. [63] evaluated the conjugation of pectin and albumin using the Maillard reaction to increase the emulsifying properties and reported that the conjugates had lower zeta potential values than the respective electrostatic complex. These researchers concluded that the involvement of more amino acid residues for the covalent linkage with carboxyl groups of pectin in the conjugates is responsible for lower values of zeta potential. ...
... These researchers concluded that the involvement of more amino acid residues for the covalent linkage with carboxyl groups of pectin in the conjugates is responsible for lower values of zeta potential. Our finding is not in agreement with that of Chen, Ji, Qiu, Liu, Zhu, and Yin [63]. Except for nanoemulsions stabilized by the mixture and the conjugate of BSG/Alb, other nanoemulsions stabilized by the mixture or conjugate of same biopolymers did not significantly differ in zeta potential values after preparation. ...
Protein conjugation with the Maillard reaction has received considerable attention in the past decades in terms of improving functional properties. This study evaluated the changes in the techno-functional properties of whey protein isolate (WPI), soy protein isolate (SPI), and albumin (Alb) after conjugation with basil seed gum (BSG). The conjugates were developed via the Maillard reaction. Various analyses including FT-IR, XRD, SEM, SDS-PAGE, DSC, RVA, rheology, zeta potential, emulsion, and foaming ability were used for evaluating conjugation products. Conjugation between proteins (WPI, SPI, Alb) and BSG was validated by FT-IR spectroscopy. XRD results revealed a decrease in the peak of BSG after conjugation with proteins. SDS-PAGE demonstrated the conjugation of WPI, SPI, and Alb with BSG. DSC results showed that conjugation with BSG reduced the Tg of WPI, SPI, and Alb from 210.21, 207.21, and 210.90 °C to 190.30, 192.91, and 196.66 °C, respectively. The emulsion activity and emulsion stability of protein/BSG conjugates were increased significantly. The droplet size of emulsion samples ranged from 112.1 to 239.3 nm on day 3. Nanoemulsions stabilized by Alb/BSG conjugate had the smallest droplet sizes (112.1 and 143.3 nm after 3 and 17 days, respectively). The foaming capacity of WPI (78.57%), SPI (61.91%), and Alb (71.43%) in their mixtures with BSG increased to 107.14%, 85.71%, and 85.71%, respectively, after making conjugates with BSG. The foam stability of WPI (39.34%), SPI (61.57%), and Alb (53.37%) in their mixtures with BSG (non-conjugated condition) increased to 77.86%, 77.91%, and 72.32%, respectively, after formation of conjugates with BSG. Conjugation of BSG to proteins can improve the BSG applications as a multifunctional stabilizer in pharmaceutical and food industries.
... Therefore, since the emulsifying ability of SBP is superior to that of commercial pectin, it is an innovative idea to combine the SBP polysaccharide with CP through glycosylation reactions and improve the emulsifying stability of the protein. In our previous study [20], the stability of the CP-stabilized emulsion was improved by adding SBP. However, the impact of glycosylation with SBP on the adsorption behaviour of CP at the oil-water interface and dilatational viscoelastic properties of the adsorption layer, as well as the relationship between the interfacial behaviour and emulsion stability, have not been reported. ...
... The preparation of SBP-CP conjugates was based on the method described by Kasran et al. [22], and the reaction conditions were described by Chen et al. [20]. A simple methodological schematic is shown in Fig. 1. ...
The aim of the present study was to investigate the effect of glycosylation with sugar beet pectin (SBP) on the interfacial behaviour and emulsifying ability of coconut protein (CP). The physical stabilities of the emulsions were predicted by transmission variation, droplet distribution and zeta potentials. The results showed that SBP-CP-stabilized emulsions showed better stability during centrifugation than those stabilized by CP because SBP-CP reduced the degree of variation in the CP transmission profile. The adsorption kinetics of all emulsifiers at the oil-water interface were determined to investigate the relationship between the interfacial behaviour and emulsion stability. The presence of SBP considerably reduced the adsorption rate of CP (0.698 mN/m/s1/2) and hampered the development of a highly viscoelastic network at the oil-water interface. The values of the dilatational elastic modulus (Ed = 19.477 mN/m) and dilatational viscous modulus (E = 19.719 mN/m) were approximately equal, indicating that the adsorption process was mainly dominated by elastic behaviour. Additionally, the SBP-CP interaction enhanced the dilatational property of the CP-absorbed layer.
... The amphiphilic nature of proteins allows its strong adsorption at the oil-water interface that generates electrostatic and steric stabilization due to the formation of the interfacial film [9]. Differently, the polysaccharides mainly generate a thick steric layer by partially protruding into the aqueous phase to provide electrostatic repulsive forces against droplet aggregation [10]. ...
... For GLT emulsion, the droplet size distribution was unimodal at various pH value (pH 3-11). The mean droplet size of emulsion increased from 49.4 to 64.1 μm when pH varied from 3 to 5, then gradually decreased as pH further increased (pH [5][6][7][8][9][10][11]. This phenomenon could be tentatively explained by the isoelectric point (approximately pH 5) of type B gelatin, which resulted in the GLT aggregation that adsorbed to the interface and then increased the droplet size of emulsion [21,55]. ...
In this study, the pineapple peel cellulose nanofibrils (PCNFs) were facilely isolated by a dilute alkali assisted ball milling technique, then used to adjust the stabilization of low internal phase oil-in-water emulsions (oil phase 30 vol%) stabilized by gelatin (GLT, 1 wt%). The ball milling with the aid of NaOH solution (3 wt%) efficiently promoted the purification and defibrillation of cellulose through a one-pot approach, showing an average length of 0.77 μm and crystallinity index of 43.5 %. With the increase of PCNFs concentration (0–1.0 wt%), the emulsions showed an increased droplet size (51.2–76.9 μm) and a gradually decreasing bottom water layer. The apparent viscosity, storage modulus (G') and loss modulus (G") of emulsions evidently increased with increasing PCNFs addition. The result of confocal laser scanning microscopy (CLSM) confirmed the stabilization mechanism of GLT/PCNFs emulsions, involving the interface adsorption by GLT and the formation of viscoelastic network structure by PCNFs. The environmental stabilities of GLT emulsion could be improved by introducing PCNFs, except for at high ionic strength (> 100 mM). Notably, PCNFs effectively avoided the adverse effect of GLT isoelectric point (pH 5) on the stability of emulsion.
... In addition, conjugated compounds with loose structure have better emulsifying properties because the flexible structure can be adsorbed to the oil droplet surface more quickly. Long time coupling would cause conjugates from loose porous to flat, and appear tight macrostructure (Chen et al. 2018). ...
During the application of Whey proteins (WPs), they often have complex interactions with saccharides (Ss), another important biopolymer in food substrate. The texture and sensory qualities of foods containing WPs and Ss are largely influenced by the interactions of WPs-Ss. Moreover, the combination of WPs and Ss is possible to produce many excellent functional properties including emulsifying properties and thermal stability. However, the interactions between WPs-Ss are complex and susceptible to some processing conditions. In addition, with different interaction ways, they can be applied in different fields. Therefore, the non-covalent interaction mechanisms between WPs-Ss are firstly summarized in detail, including electrostatic interaction, hydrogen bond, hydrophobic interaction, van der Waals force. Furthermore, the existence modes of WPs-Ss are introduced, including complex coacervates, soluble complexes, segregation, and co-solubility. The covalent interactions of WPs-Ss in food applications are often formed by Maillard reaction (dry or wet heat reaction) and occasionally through enzyme induction. Then, two common influencing factors, pH and temperature, on non-covalent/ covalent bonds are introduced. Finally, the applications of WPs-Ss complexes and conjugations in improving WP stability, delivery system, and emulsification are described. This review can improve our understanding of the interactions between WPs-Ss and further promote their wider application.
... Two carboxylic acid groups from the aspartic and glutamic acids provide hydrogen atoms for reducing O 2 to H 2 O [14,16,17]. In addition, because of its excellent catalytic oxidation ability, laccase is widely used in organic synthesis [18], food processing [19], textile-dye decolorization [20,21], environmental-pollutant detoxification [22], and biosensors [23]. However, the application of free laccase in pollutant degradation involves certain limitations relating to stability, reusability, and activity retention across wide ranges of temperatures and pH values. ...
Mesotrione (MES) is a new environmental pollutant. Some reports have indicated that microbial enzymes could be utilized for MES degradation. Laccase is a green biocatalyst whose potential use in environmental pollutant detoxification has been considered limited due to its poor stability and reusability. However, these issues may be addressed using enzyme immobilization. In the present study, we sought to optimize conditions for laccase immobilization, to analyze and characterize the characteristics of the immobilized laccase, and to compare its enzymatic properties to those of free laccase. In addition, we studied the ability of laccase to degrade MES, and analyzed the metabolic pathway of MES degradation by immobilized laccase. The results demonstrated that granular zinc oxide material (G-ZnO) was successfully used as the carrier for immobilization. G-ZnO@Lac demonstrated the highest recovery of enzyme activity and exhibited significantly improved stability compared with free laccase. Storage stability was also significantly improved, with the relative enzyme activity of G-ZnO@Lac remaining at about 54% after 28 days of storage (compared with only 12% for free laccase). The optimal conditions for the degradation of MES by G-ZnO@Lac were found to be 10 mg, 6 h, 30 °C, and pH 4; under these conditions, a degradation rate of 73.25% was attained. The findings of this study provide a theoretical reference for the laccase treatment of 4-hy-droxyphenylpyruvate dioxygenase (HPPD)-inhibiting herbicide contamination.
... Conjugates formed by the Maillard reaction have the potential to improve emulsification properties, solubilization, foam formation capacity, foam stability, antioxidant capacity, and kinetic stability of proteins and can be used in controlled release systems and encapsulation (Chen et al., 2018;Martinez-Alvarenga et al., 2014;Nagaraju et al., 2021;Qi, Xiao, & Wickham, 2017;Wang et al., 2017). Furthermore, conjugates can reduce protein digestibility (Joubran, Moscovici, Portmann, & Lesmes, 2017;Zhang et al., 2023). ...
A B S T R A C T
Background: Modifying proteins through the Maillard reaction has garnered significant attention from researchers. The amino group of a protein and the carbonyl group of a carbohydrate covalently interact, forming conjugates. The production of conjugates is compelling due to the improvement of protein properties, such as
emulsification, solubilization, foam formation ability, antioxidant capacity, kinetic stability, and even reduction of allergenicity. Producing conjugates via the Maillard reaction is a strategy that can enhance the utilization of proteins with limited technological properties. Furthermore, the use of prebiotic fibers as a source of carbonyl for covalent bonds with proteins allows for the creation of a new functional ingredient. This new ingredient can be used for targeted and selective delivery of proteins to intestinal probiotics. The conjugates are characterized by their resistance to gastrointestinal digestion, ensuring that a portion of the protein reaches the colon. The prebiotic fraction of the conjugate imparts selectivity for the growth and proliferation of probiotics.
Scope and approach: This review provides an overview of the main concepts of the Maillard reaction and the factors that influence the reaction rate. We highlighted the use of prebiotic dietary fibers to enhance the technological and functional properties of the proteins. Additionally, we emphasized the production of a functional ingredient targeted towards colonic probiotics because of the covalent bonding between prebiotic dietary fibers and proteins.
Key findings and conclusions: The protein-carbohydrate conjugation via the Maillard reaction can be a promising strategy for enhancing proteins’ technological and functional properties. These conjugates should be produced under controlled conditions of temperature, time, type, and size of the carbohydrate, protein-carbohydrate ratio, and pH, aiming to limit the reaction to the initial stage. Thus, there is a significant challenge in finding and
controlling the optimal process conditions that ensure the improvement of the techno-functional properties of proteins. Additionally, protein/carbohydrate conjugates may possess immunomodulatory and anti-inflammatory capabilities, making them suitable for targeted delivery to the intestinal microbiota. This turns them into promising ingredients for both the food and pharmaceutical industries.
... Furthermore, BSA has been found to accumulate in tumor tissues, leading to a higher drug delivery rate to the targeted cells [17]. In addition, the combination of BSA with natural polysaccharides such as dextran, chitosan, hyaluronic acid, pectin, and alginate enhances the stability of the nanocarriers and helps to avoid undesired drug leakage by changing the diffusion properties of the shell material [18][19][20][21][22]. Among these polysaccharides, dextran takes significant attention because of its biocompatibility, chemical functionality, and potential for decreased immunogenicity [23]. ...
Nanocarrier systems are widely used for drug delivery applications, but limitations such as the use of synthetic surfactants, leakage of toxic drugs, and a poor encapsulation capacity remain as challenges. We present a new hybrid nanocarrier system that utilizes natural materials to overcome these limitations and improve the safety and efficacy of drug delivery. The system comprises a biopolymeric shell and a lipid core, encapsulating the lipophilic anticancer drug paclitaxel. Bovine serum albumin and dextran, in various molecular weights, are covalently conjugated via Maillard reaction to form the shell which serves as a stabilizer to maintain nanoparticle integrity. The properties of the system, such as Maillard conjugate concentration, protein/polysaccharide molar ratio, and polysaccharide molecular weight, are optimized to enhance nanoparticle size and stability. The system shows high stability at different pH conditions, high drug loading capacity, and effective in vitro drug release through the trigger of enzymes and passive diffusion. Serine proteases are used to digest the protein portion of the nanoparticle shell to enhance the drug release. This nanocarrier system represents a significant advancement in the field of nanomedicine, offering a safe and effective alternative for the delivery of lipophilic drugs.
Graphical abstract
... What is more, aqueous methanol gives a higher extraction yield in comparison to hexane and acetone when phenolics were isolated from wheat brans [134]. The ASE extraction is more efficient in yield and retains the biological activity better in comparison to hot water maceration (determined according to oxygen radical absorbance capacity, DPPH, and hydroxyl radical scavenging ability) of polysaccharides extracted from Chimonobambusa quadrangularis [137]. The ASE extract from flowers of M. sativa (70% ethanol) was most efficient in the extraction of compounds regarding the total phenolic content and antioxidant activity [138]. ...
This review describes the role of silicon (Si) in plants. Methods of silicon determination and speciation are also reported. The mechanisms of Si uptake by plants, silicon fractions in the soil, and the participation of flora and fauna in the Si cycle in terrestrial ecosystems have been overviewed. Plants of Fabaceae (especially Pisum sativum L. and Medicago sativa L.) and Poaceae (particularly Triticum aestivum L.) families with different Si accumulation capabilities were taken into consideration to describe the role of Si in the alleviation of the negative effects of biotic and abiotic stresses. The article focuses on sample preparation, which includes extraction methods and analytical techniques. The methods of isolation and the characterization of the Si-based biologically active compounds from plants have been overviewed. The antimicrobial properties and cytotoxic effects of known bioactive compounds obtained from pea, alfalfa, and wheat were also described.
... Bacillus atrophaeus recombinant laccase covalently immobilized on magnetic iron nanoparticles, and then used them to remove phenols and clarify plant juice samples [90] T. versicolor covalent conjugation of bovine serum albumin and sugar beet pectin (SBP) improve the stability of emulsifying beet pectin [155] ...
Industrialization, intensive farming, rapid population growth and urbanization are the source of a large number of pollutants entering the environment. The current concentration of xenobiotics released into the environment exceeds its natural ability to decompose them. Enzymatic degradation of pollutants seems to be an environmentally friendly process. Due to the wide spectrum of substrate specificity, from inorganic compounds to high molecular weight organic compounds such as PAH or dyes, as well as favorable biochemical properties, laccase has been used in the biological removal of xenobiotics from the environment. It is important to understand the degradation mechanisms of pollutants and to evaluate the final products in terms of their toxicity. The laccase oxidizes the substrates with the simultaneous reduction of molecular oxygen to water, which is the purest reaction co-substrate. That is why it is called a green biocatalyst. The trend is an increase in the production of enzymes related to the intensive development of industry, bioremediation or synthetic chemistry. This leads to the search for laccases with greater activity and stability under extreme conditions. The potential of laccases to degrade xenobiotics can be promoted by improving enzymatic catalytic characterization using protein engineering and other genetic engineering methods.
... In recent years, the complexation of polysaccharides and proteins by covalent (Maillard reaction or enzymatic catalysis) (Chen et al., 2018) or non-covalent (electrostatic interaction) (Lin et al., 2020a) modification had gained great attraction since it could integrate the merits of both polymers to exhibit better emulsification performance (Evans et al., 2013). As compared to the electrostatic complexation, covalently conjugated with polysaccharides significantly improved the adaptability of polysaccharide-protein conjugates stabilised emulsions to environmental stresses, such as pH values, ionic strength and thermal treatment (Ru et al., 2012). ...
This work aimed to elucidate the relationship between the chemical components of soybean soluble polysaccharide (SSPS) and its Maillard reaction with soybean protein isolate (SPI). Enzymatic hydrolysis was used to specifically cleave the chemical components of SSPS. Neutral sugar side chain regions of SSPS were easier to conjugate with SPI than the backbone containing galacturonic acid. The modified SSPS with higher content of arabinose showed the highest degree of glycosylation (46.8%). SSPS‐SPI conjugates exhibited lower interfacial tension than SPI, fabricating emulsion with smaller droplets size and better emulsion stability. The improved emulsifying properties could be ascribed to two aspects: (i) a higher percentage of adsorbed protein at the interface to cover more oil droplet surface; (ii) thicker adsorbed layer thickness onto the droplet surface to provide stronger steric‐hindrance effect to prevent droplet coalescence.
... The conjugated polysaccharide-protein products are touted as a great determinant of gelatin quality because this product appears to have a high molecular weight as compared to the pure or untreated product. The higher the molecular weight, the better and stable the gelatin quality and functionality ( Chen et al., 2018 ). Additionally, modified gelatin obtained in our work could act as a stabilized emulsifying agent according to the electrophoretic results in Fig. 3 A-B, which indicated the intermolecular conjugation, which possibly showed that our products could have high molecular weight and as such exhibit good emulsifying properties [Surh et al., 2006] . ...
The fish gelatin (FG), a good alternative for unhealthy and limited socio-cultural mammalian gelatin appears to possess endogenous structural limitations. The goal of this work was to use enzymatic crosslinking to modify cold-water fish gelatin (FG) with beet pectin. Reaction conditions were optimized by a single factorial experiment and covalent crosslinking was measured by ultraviolet (UV)-Vis spectroscopy at 340 nm to indicate Horseradish Peroxidase (HRP) catalyzes beet pectin (BP). At 50°C for 4 hours, the highest weight ratio of heterologous adducts between FG-BP was 1:3, with HRP and Hydrogen peroxide (H2O2) of 2 µg/mL and 0.067%, (v/v), respectively. Intermolecular cross-linking was found between treated samples using ATR-FTIR and Sodium Dodecyl Sulphur and Polyacrylamide Gel Electrophoresis (SDS-PAGE). The heterologous product, control FG, and BP as well as a mixture of untreated FG-BP had a β-sheet of 41.14%, 39.65%, 39.9%, and 40.0% respectively. The maximum reduction in elution was obtained in heterogeneous FG-BP complex. Furthermore, a schematic mechanism for Cold-water Fish gelatin and beet pectin was proposed. Overall, peroxidase crosslinked BP was able to modify cold-water fish gelatin. The use of horseradish peroxidase on fish gelatin could provide a practical way of building the FG-BP complex as a basis for understanding the FG functionalities comprehensively.
... During the food storage, elevated levels of O 2 lead to a detrimental oxidation and decreased food quality. Thus laccase is used as an oxygen scavenger for better food packaging and for the elimination of unwanted phenolic compounds in baking, beer and wine stabilization and in juice processing [34,40]. Laccase is also employed in ascorbic acid determination, sugar beet-pectin gelation, and for treating the olive mill wastewater [18]. ...
Laccases constitute a family of copper-containing oxidase enzymes which catalyze the oxidation of various aromatic compounds (particularly of phenolic and aromatic amines) and some inorganic ions, and simultaneously reduce oxygen to water. The laccase molecule is either a dimeric or tetrameric glycoprotein containing four copper atoms per monomer, which are distributed across three redox sites. It was discovered by Yoshida in 1883 in Rhus vernicifera (Japanese lacquer tree). Laccase molecules are of common occurrence in higher plants, some fungi, insects and bacteria. These are now considered as the industrial enzymes because of their wide substrate specificity. Besides discussing the production and activity of laccases in various organisms, this article examines their wider potential for diverse biotechnological applications (e.g. in biosensor technology, cosmetics, food improvement, wine and beer stabilization, medical diagnosis, pharmaceutical industry, agriculture, petrochemicals, paper and pulp industry) as well as their use in detoxification and bioremediation of synthetic dyes. Further, it elucidates the process of enzyme immobilization, as immobilized enzymes also have a variety of applications.
Objectives
Walnut protein–galactooligosaccharide (WalPI–GOS) nanoparticles were used to prepare high internal phase Pickering emulsions (HIPPEs).
Materials and Methods
The entrapment properties of HIPPEs for cinnamon oil were investigated by varying the volume ratios of camellia and cinnamon oils (cinnamon oil contents: 0%, 2.5%, 5.0%, 10%, 15%, and 20%), and the droplet size, rheological properties, Raman spectroscopy results, microstructure, thermal stability, storage stability, and antioxidant activity of HIPPEs were determined.
Results
The droplet size of HIPPEs increased with increasing cinnamon oil content. Among the samples, HIPPEs enriched with the cinnamon oil content of 10% had the highest storage modulus, loss modulus, and apparent viscosity (13.64 Pa·s). However, the thixotropic recovery ability of HIPPEs decreased with the increase in cinnamon oil content. Raman spectroscopy and microstructural analysis revealed that proteins covalently cross-linked with cinnamaldehyde to form a three-dimensional network structure, which showed the highest stability when the cinnamon oil content was 10%. HIPPEs exhibited high thermal stability without delamination after heating, as well as good storage stability without delamination or discoloration after 15 d of storage at 25 °C and 50 °C. Among the samples, HIPPEs enriched with 10% cinnamon oil had the lowest peroxide and malondialdehyde values during storage. The addition of cinnamon oil significantly enhanced the antioxidant activity of HIPPEs.
Conclusions
The best overall performance of HIPPEs was achieved at a cinnamon oil content of 10%. This result provides a theoretical foundation for the development of WalPI and the application of cinnamon oil in food, as well as a theoretical basis for the development of novel food delivery systems.
Aim:
The present study was conducted to produce a new carrier containing whey protein isolate-basil seed gum (WPI-BSG) conjugate to achieve superior physicochemical stability of emulsions containing vitamin D3 (Vit-D3).
Methods:
Zeta-potential and particle size analysis, spectrophotometric method, encapsulation efficiency, loading capacity and dialysis bag method were used to examined physicochemical stability and Vit-D3 release from the emulsions.
Results:
The conjugate-stabilised emulsion showed maximum encapsulation efficiency (87.05 ± 3.37% (w/w)) and loading capacity (5.43 ± 0.08% (w/w)) at the Vit-D3 concentration of 200 and 300 mg/kg. This emulsion also demonstrated good physical stability after 30 days of storage with the zeta potential and mean droplet size of -79.60 ± 0.62 mV and 1346.82 ± 5.95 nm, respectively. Additionally, the conjugate-stabilised emulsion had a maximum Vit-D3 retention (chemical stability) of 72.79 ± 3.58% after a 15-day storage period.
Conclusion:
Our findings suggest that the conjugate-stabilised emulsion has a good stabilising capacity as a carrier for hydrophobic compounds such as Vit-D3.
The ultrasound-assisted extraction conditions of Thesium chinense Turcz. crude polysaccharide (TTP) were optimized, and a TTP sample with a yield of 11.9% was obtained. TTP demonstrated the ability to stabilize high-internal-phase oil-in-water emulsions with an oil phase volume reaching up to 80%. Additionally, the emulsions stabilized by TTP were examined across different pH levels, ionic strengths, and temperatures. The results indicated that the emulsions stabilized by TTP exhibited stability over a wide pH range of 1–11. The emulsion remained stable under ionic strengths of 0–500 mM and temperatures of 4–55 °C. The microstructure of the emulsions was observed using confocal laser scanning microscopy, and the stabilization mechanism of the emulsion was hypothesized. Soluble polysaccharides formed a network structure in the continuous phase, and the insoluble polysaccharides dispersed in the continuous phase, acting as a bridge structure, which worked together to prevent oil droplet aggregation. This research was significant for developing a new food-grade emulsifier with a wide pH range of applicability.
The poor thermal stability of lactoferrin (LF) hinders its bioavailability and use in commercial food products. To preserve LF from thermal denaturation, complexation with other biopolymers has been studied. Here we present the complex formation conditions, structural stability, and functional protection of LF by α‐lactalbumin (α‐LA). The formation of the LF–α‐LA complexes was dependent on pH, mass ratio, and ionic strength. Changing the formation conditions and cross‐linking by transglutaminase impacted the turbidity, particle size, and zeta‐potential of the resulting complexes. Electrophoresis, Fourier‐transform infrared spectroscopy, and circular dichroism measurements suggest that the secondary structure of LF in the LF–α‐LA complex was maintained after complexation and subsequent thermal treatments. At pH 7, the LF–α‐LA complex protected LF from thermal aggregation and denaturation, and the LF retained its functional and structural properties, including antibacterial capacity of LF after thermal treatments. The improved thermal stability and functional properties of LF in the LF–α‐LA complex are of interest to the food industry.
Conjugation with glucose (G) and fructose (F) via the Maillard reaction under the wet-heating condition is a natural and non-toxic method of improving the technological functions of 7S/11S proteins in different kinds of gels. It may be used as an affordable supply of emulsifiers and an excellent encapsulating matrix for gels. This study aimed to create a glucose/fructose-conjugated 7S/11S soy protein via the Maillard reaction. The conjugation was confirmed by determining the SDS-PAGE profile and circular dichroism spectra. In addition, these conjugates were comprehensively characterized in terms of grafting degree, browning degree, sulfhydryl content, surface hydrophobicity (H0), and differential scanning calorimetry (DSC) through various reaction times (0, 24, 48, and 72 h) to evaluate their ability to be used in food gels. The functional characteristics of the 7S/11S isolate–G/F conjugate formed at 70 °C, with a high degree of glycosylation and browning, were superior to those obtained at other reaction times. The SDS-PAGE profile indicated that the conjugation between the 7S and 11S proteins and carbohydrate sources of G and F through the Maillard reaction occurred. Secondary structural results revealed that covalent interactions with G and F affected the secondary structural components of 7S/11S proteins, leading to increased random coils. When exposed to moist heating conditions, G and F have significant potential for protein alteration through the Maillard reaction. The results of this study may provide new insights into protein modification and establish the theoretical basis for the therapeutic application of both G and F conjugation with soy proteins in different food matrixes and gels.
There is an impairment of skin integrity derived from derangement of orthorhombic lateral organization caused by dysregulation of ceramide (CER) amounts in the skin barrier. The impaired skin barrier is replenished via CER, fatty acid, and cholesterol-containing nano-based formulations. However, it is still a challenge to formulate CER-containing-liposomes due to their chemical structure with poor aqueous solubility and high molecular weight. In this study, the design and optimization of CER-NP loaded liposomes are implemented by Response Surface Methodology (RSM) based on the quality-by-design approach. The formulation optimization process of liposomes containing CER-NP was carried out using the Design of Expert. The Central Composite Design was the design type with 3 factors at 5 levels: plus and minus alpha (axial points), plus and minus (factorial points), and the center point. The parameters were CER-NP, fatty acid, and cholesterol at 5 variable levels as independent variables. The responses were the particle size and PDI values of liposomes as responses which were measured using dynamic light scattering (DLS). The optimum formulation was selected based on mean particle size (136.6 ±4.05) and PDI values (0.248 ±0.012), and the prediction model success was evaluated based on the equation on the quadratic model. The encapsulation efficiency was clarified by sampling the CER-NP-loaded liposome with the centrifugal ultrafiltration method and analysis in high-
performance liquid chromatography (HPLC). The Cer-NP release from liposome was examined based on the in vitro release (IVRT). MTT assay was also performed on HaCaT human keratinocyte cell lines to assess the relative safety of the optimized liposomes loaded CER-NP. The experimental result (PS:136.6±4.05 nm and PDI: 0.248 ±0.012) and predicted result (PS:132.6 nm and PDI:0.278) were correlated. The CLSM image was conformable with the other studies and the encapsulation efficiency of CER-NP was 93.84±0.87%. The release profile was fitted with the Korsmeyer-Peppas model. The cytotoxicity studies showed that the liposomes for topical administration of CER-NP could be considered relatively safe. In conclusion, the optimized liposomes containing CER-NP could have the potential to restore the skin barrier function.
Keywords: Ceramide, liposome, skin barrier function, experimental design, topical administration
The present study was conducted to optimize the preparation conditions of whey protein isolatebasil seed gum (WPI-BSG) conjugates resulting from the Maillard reaction in different weight ratios and reaction times. In addition, the stability of the emulsions stabilized by WPI-BSG conjugate was investigated. The covalent attachment of BSG to WPI was effectively confirmed by OPA method, FTIR and fluorescence spectrometry analysis. Results indicated that the maximum zeta potential (-79.83 ± 1.62 mV), emulsifying activity (29.33 ± 2.71 m2/g) and emulsifying stability (45.16 ± 5.14 min) of conjugates were obtained in the weight ratio of 1:2 (WPI to BSG) and reaction time of 2 h. It was also found that a longer heating time may lead to an increase in the browning intensity and a significant decrease in the emulsifying properties of the conjugates. Moreover, according to the results of particle size, zeta potential and creaming index, the emulsions stabilized by WPI-BSG conjugates were more stable than those stabilized by unheated WPI and WPI-BSG mixture. This study indicates that the Maillard reaction can successfully improve the emulsifying properties of WPI. Besides, WPI-BSG conjugates are able to increase physical stability of oil-in-water emulsions.
Emulsion systems are extensively utilized in the food industry, including dairy products, such as ice cream and salad dressing, as well as meat products, beverages, sauces, and mayonnaise. Meanwhile, diverse advanced technologies have been developed for emulsion preparation. Compared with other techniques, high‐intensity ultrasound (HIUS) and high‐pressure homogenization (HPH) are two emerging emulsification methods that are cost‐effective, green, and environmentally friendly and have gained significant attention. HIUS‐induced acoustic cavitation helps in efficiently disrupting the oil droplets, which effectively produces a stable emulsion. HPH‐induced shear stress, turbulence, and cavitation lead to droplet disruption, altering protein structure and functional aspects of food. The key distinctions among emulsification devices are covered in this review, as are the mechanisms of the HIUS and HPH emulsification processes. Furthermore, the preparation of emulsions including natural polymers (e.g., proteins‐polysaccharides, and their complexes), has also been discussed in this review. Moreover, the review put forward to the future HIUS and HPH emulsification trends and challenges. HIUS and HPH can prepare much emulsifier‐stable food emulsions, (e.g., proteins, polysaccharides, and protein–polysaccharide complexes). Appropriate HIUS and HPH treatment can improve emulsions’ rheological and emulsifying properties and reduce the emulsions droplets’ size. HIUS and HPH are suitable methods for developing protein–polysaccharide forming stable emulsions. Despite the numerous studies conducted on ultrasonic and homogenization‐induced emulsifying properties available in recent literature, this review specifically focuses on summarizing the significant progress made in utilizing biopolymer‐based protein–polysaccharide complex particles, which can provide valuable insights for designing new, sustainable, clean‐label, and improved eco‐friendly colloidal systems for food emulsion.
Practical Application
Utilizing complex particle‐stabilized emulsions is a promising approach towards developing safer, healthier, and more sustainable food products that meet legal requirements and industrial standards. Moreover, the is an increasing need of concentrated emulsions stabilized by biopolymer complex particles, which have been increasingly recognized for their potential health benefits in protecting against lifestyle‐related diseases by the scientific community, industries, and consumers.
Pickering emulsions have been widely studied due to their good stability and potential applications. Nanocellulose including cellulose nanocrystals (CNCs), cellulose nanofibrils (CNFs), and bacterial cellulose nanofibrils (BCNFs) has emerged as sustainable stabilizers/emulsifiers in food-related Pickering emulsions due to their favorable properties such as renewability, low toxicity, amphiphilicity, biocompatibility, and high aspect ratio. Nanocellulose can be widely obtained from different sources and extraction methods and can effectively stabilize Pickering emulsions via the irreversible adsorption onto oil-water interface. The synergistic effects of nanocellulose and other substances can further enhance the interfacial networks. The nanocellulose-based Pickering emulsions have potential food-related applications in delivery systems, food packaging materials, and fat substitutes. Nanocellulose-based Pickering emulsions as 3D printing inks exhibit good injectable and gelling properties and are promising to print spatial architectures. In the future, the utilization of biomass waste and the development of "green" and facile extraction methods for nanocellulose production deserve more attention. The stability of nanocellulose-based Pickering emulsions in multi-component food systems and at various conditions is an utmost challenge. Moreover, the case-by-case studies on the potential safety issues of nanocellulose-based Pickering emulsions need to be carried out with the standardized assessment procedures. In this review, we highlight key fundamental work and recent reports on nanocellulose-based Pickering emulsion systems. The sources and extraction of nanocellulose and the fabrication of nanocellulose-based Pickering emulsions are briefly summarized. Furthermore, the synergistic stability and food-related applications of nanocellulose-stabilized Pickering emulsions are spotlighted.
Due to the higher consumption, increased demand of animal based hydrocolloids and problems associated with animal based hydrocolloids are religious beliefs and mad cow disease, researchers are looking for alternative sources of hydrocolloids like marine and plant based hydrocolloids. Objective: To evaluate the gelling properties of red kidney beans protein isolates with different gums. Methods: The gelling powder developed with red kidney bean protein (KPI)-carrageenan (CG) and protein-xanthan (XG) gum with six different concentrations. Results: Added protein increased the plasticity of the gel and showed a higher blooms strength and hardness in all treatments except T1. KPI-CG gel had bloom strength values 198.67 ±1.53g, 249.67 ±1.53g and 282.33 ±1.56g and respectively KPI-XG gel bloom strength values were 170.33 ±1.6g, 232.67 ±2.08g and 256.67 ±2.52g; while hardness of KPI-CG gel shows 23.5 ±0.5N, 37 ±1N, 42.33 ±1.54N and 22 ±1N, 34 ±1N, 40 ±1N of KPI-XG gel respectively. The lower Gˈˈ values than Gˈ indicate that there is gelling ability in all the concentrations. Added carrageenan-protein gelling agent with maximum gum concentration showed the highest gel strength of 1629.99±16.12 pa which is double the amount of KPI-XG gel elasticity 878.043±8.08 pa. Conclusions: These results indicate that the KPI-CG mixed gel has a better gelling strength. The outcomes of this work will be used to provide the groundwork for developing a novel designed plant protein-based gel system and the use of gel in yoghurt, which might increase functionality over protein or gums alone and replace the animal-based gelling component.
A β-carotene rich emulsion with improved physical and chemical stability was obtained in this study, using different types of protein-polysaccharide-polyphenol ternary complexes as novel emulsifiers. The ternary complexes were prepared by covalent or non-covalent binding of soy protein isolate (SPI), β-glucan (DG) and myricetin (MC), which were evidenced to be stable. It was indicated that the emulsion stabilized by covalent complex of SPI, DG and MC, exhibited higher zeta-potential and smaller particle size than those stabilized by non-covalent complex. Furthermore, the covalent complexes prepared from different addition sequences showed different efficiencies in stabilizing the emulsion, in which SPI-DG-MC and SPI-MC-DG-stabilized emulsions possess better stability, emulsifying activity and storage resistance under adverse environmental treatment, with CI values of 62.7% and 64.3% after 25 days, respectively. According to oxidative stability and rheology analysis of the emulsions, it was found that the SPI-MC-DG complex prepared at the ratio of 4:2:1 was more stable with relatively less lipid oxidation products and a tighter stacking structure, and the final LH value was 39.98 mmol/L and the MDA value was 6.34 mmol/L. These findings implied that the ternary complex has the potential to deliver fat-soluble active ingredient by means of emulsion, but which depends on the mode and sequence of the molecular interactions.
Maillard reaction browning is one of the quality deterioration in dried fruit products, but how pectin affects Maillard reaction in the fruit drying and storage process is not clear. This study aimed at investigating the mechanism of pectin variation impact on the browning of Maillard reaction by using simulated system (l-lysine, d-fructose and pectin) in thermal (60 °C and 90 °C for 8 h) and storage (37 °C for 14 days) process. Results showed that apple pectin (AP) and sugar beet pectin (SP) significantly enhanced the browning index (BI) of the Maillard reaction system by 0.01 to 134.51 in the thermal and storage processes, respectively, which were methylation degree of pectin-dependent. The pectin depolymerization product participated Maillard reaction by reacting with l-lysine, and increasing the 5-hydroxymethyl furfural (5-HMF) content (1.25-11.41-fold) and Abs420nm (0.01-0.09). It also produced a new product (m/z 225.1245), which finally increased browning level of the system.
The rapid growth of the human population in recent decades has resulted in the intensive development of various industries, the development of urban agglomerations and increased production of medicines for animals and humans, plant protection products and fertilizers on an unprecedented scale. Intensive agriculture, expanding urban areas and newly established industrial plants release huge amounts of pollutants into the environment, which, in nature, are very slowly degraded or not decomposed, which leads to their accumulation in water and terrestrial ecosystems. Researchers are scouring extremely contaminated environments to identify organisms that have the ability to degrade resistant xenobiotics, such as PAHs, some pharmaceuticals, plasticizers and dyes. These organisms are a potential source of enzymes that could be used in the bioremediation of industrial and municipal wastewater. Great hopes are pinned on oxidoreductases, including laccase, called by some a green biocatalyst because the end product of the oxidation of a wide range of substrates by this enzyme is water and other compounds, most often including dimers, trimers and polymers. Laccase immobilization techniques and their use in systems together with adsorption or separation have found application in the enzymatic bioremediation of wastewater.
Recently, increasing studies have shown that the functional properties of proteins, including emulsifying properties, antioxidant properties, solubility, and thermal stability, can be improved through glycation reaction under controlled reaction conditions. The use of glycated proteins to stabilize hydrophobic active substances and to explore the gastrointestinal fate of the stabilized hydrophobic substances has also become the hot spot. Therefore, in this review, the effects of glycation on the structure and function of food proteins and the physical stability and oxidative stability of protein‐stabilized oil/water emulsions were comprehensively summarized and discussed. Also, this review sheds lights on the in vitro digestion characteristics and edible safety of emulsion stabilized by glycated protein. It can further serve as a research basis for understanding the role of structural features in the emulsification and stabilization of glycated proteins, as well as their utilization as emulsifiers in the food industry.
Food packaging is developed primarily for food safety and long shelf life. Advancements in material science and comprehensive encapsulation technologies provide numerous innovative packaging solutions for prolonging shelf-life and improving the quality and safety of food products. Among the conventional encapsulation methods, Pickering emulsions (PEs) as a stable alternative with food-grade colloidal particles have shown excellent performance in food packaging formulations.
Recent advances in PEs have attracted wide attention because of their higher stability and functionality. Using PE technology for the preparation of composite materials is a green and efficient method that has multiple uses in the food packaging field. PEs are stable emulsion systems that are stabilized by solid particles instead of surfactants. A PE has improved physical stability due to the solid particles irreversibly adsorbing on the oil-water interface and preventing droplets
from aggregating. Food-grade particles have opened up new opportunities for PEs in the food packaging industry due to their use in food science.
Currently, PEs systems are in high demand in food packaging materials, which is extremely important for practical applications in food products. This article describes the factors affecting the stability of PEs and summarizes the different physicochemical properties of PEs in food packaging. Additionally, available food-grade particles (polysaccharide-based and protein-based) developed as Pickering stabilizers are summarized. In any case, several studies have indicated that PEs are important systems for improving water vapor barrier properties of films, as well as for transporting hydrophobic components. This article provides insight into the use of PEs in food packaging and their potential applications (e.g., improving physicochemical properties, water vapor permeability barrier, mechanical properties, and characteristics of material delivery systems). In particular, it investigated how PEs affect the physicochemical properties and surfaces of intelligent/active films and the controlled release of bioactive compounds in these systems. Finally, the application of this system of PEs in intelligent/active and nanofibers packaging was evaluated on real food samples.
This study investigated the effects of reaction time in preparation of Whey Protein-Carboxymethyl Cellulose (WP-CMC) conjugates and characterized the functional properties of the conjugates. WP-CMC conjugates were prepared under the wet heating condition of the Maillard reaction. The degree of response was distinguished by variations in the pH value, browning degree, and grafting (up to 23.24%). The emulsification performance of WP-CMC was improved, which was verified by emulsifying activity (up to 4.48% increase), particle size, zeta-potential, and other indicators by conjugates. Meanwhile, the solubility (up to 29.13% increase), 1,1-Diphenyl-2-picryl-hydrazyl Radical (DPPH•) scavenging capacity (up to 3.14 times), and iron-reducing power (up to 1.98 times) of conjugates were also improved. The results of sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) confirmed the elevated molecular weight of the binders, the fluorescence spectra showed bursts and red shifts that identified changes in the hydrophobic structure of the binders, and the Fourier infrared spectroscopy analysis responded to changes in structure and functional groups. The results showed that the optimal treatment time for WP-CMC was 140 min, and the properties and functions were better than those of the simple mixture of CMC and WP, which may play a positive role in the industrial application of WP.
This study aimed to develop functional emulsions with dietary fibre/proteins and to examine the role of interfacial rheological properties on the emulsion stability. Emulsions with inulin and various animal/vegetable proteins were prepared, and their emulsifying and interfacial rheological properties were appraised for their possible applications in stabilizing oil-in-water emulsions. Interfacial measurements including the frequency, time and strain sweep test were determined depending on the protein differences. The results revealed that the adsorption behaviour of proteins at the two interfaces was quite different. The apparent viscosity (η50) of the emulsions ranged between 0.006 and 0.037 Pa s. The highest interfacial viscosity (ηi) values at low shear rates were determined in the mixture of egg protein-inulin at the oil/water interface. In particular, the interfacial properties of egg protein were not similar to those of other proteins. This study indicated that interfacial rheological properties and emulsifying properties of the proteins were influenced by the presence of inulin which contributes to the existing body of knowledge on the preparation of the prebiotic emulsions with proteins.
Silk sericin (SS) with various biological activities has limited solubility in water and unpleasant pupal odor, which hinder its wide application in functional foods. Here, a high-yield Maillard reaction (MR) product, glycated sericin, was obtained at a concentration of 60–10 mg/mL with 18–30 mg/mL reducing sugar in a pH 10.0 aqueous solution at 90 °C for 6 h. Xylose had the highest reaction efficiency and the most obvious browning among the seven reducing sugars, followed by arabinose sugar and glucose. No matter what kind of sericin and what kind of reducing sugar, the solubility of the glycated sericin in water increased 2–3 times, and the antioxidant capacity increased 3.5–5.5 times. In particular, glycation of the sericin eliminated the pupal odor of SS and replaced it with a slightly sweet mellow fragrance. Therefore, sericin glycation opens up broad application as a health food, functional food, or food additive.
The photophysical properties of indotricarbocyanine dyes upon complexation with serum albumin have been studied, and the technique for controlling their formation using electrophoresis has been optimized. In connection with the degradation of dye molecules under the action of acids, the search for the area of localization of the dye under study on the surface of the gel plate was carried out by recording the fluorescence spectra of the dye before protein fixation and visualization followed by the completion of the protocol for obtaining electrophoregrams. To minimize the possible influence of the luminescence of the gel components, the excitation was carried out by the radiation of a semiconductor laser with a wavelength of 684 nm, which initiates the fluorescence of the studied dyes. It was established that the position of the maxima and the half-width of the fluorescence spectra of dyes with an orthophenylene bridge in the conjugation chain in the regions of the electropherogram corresponding to the localization of albumin coincide with the characteristics of the emission of dyes in initial solutions with albumin, which makes it possible to reveal the formation of covalently bound complexes of dye molecules with albumin.
The photophysical properties of indotricarbocyanine dyes upon complexation with serum albumin were studied. The technique using electrophoresis to detect their formation was optimized. The area in which the studied dye was localized on the surface of the gel plate was searched for by recording the fluorescence spectra of the dye before protein fixation and visualization followed by completion of the protocol for obtaining the electrophoregrams because the dye was degraded by acids. Excitation used radiation of a semiconductor laser with a wavelength of 684 nm, which excited fluorescence of the studied dyes, to minimize the possible influence of luminescence of the gel components. It was established that the position of the maxima and the half-width of the fluorescence spectra of dyes with an o-phenylene bridge in the conjugation chain in the regions of the electrophoregram corresponding to the location of albumin coincided with the characteristic emission of the dyes in the initial solutions with albumin, which revealed that covalently bonded complexes of the dyes with albumin formed.
Proteins as natural amphiphilic biopolymers can stabilize emulsions and are attracting intensive interest due to their abundant resource, good emulsifying properties, biocompatibility, biodegradability, nutritional benefits, and high acceptance as food ingredients. Relying on the rational design of protein-polysaccharide interactions and their differences in physicochemical properties, the interfacial structure and properties of protein-based emulsions can be effectively improved. This review summarizes the influence of various types of cellulose (i.e., nanocellulose, microcrystalline cellulose (MCC), cellulose derivatives and regenerated cellulose (RC)) on the stabilization and interaction mechanism of protein-based emulsions. The key role of cellulose in protein-based emulsions can be summarized as the following points, namely strengthening network stabilization, improving emulsifying property, adjusting emulsion structure, enhancing environmental stability and regulating lipid digestion. The application potential of protein-based emulsions focusing on fat replacer, 3D printed food, delivery vehicle, and material design can also be improved by introducing various types of cellulose.
In recent years, sugar beet pectin as a natural emulsifier has shown great potential in food and pharmaceutical fields. However, the emulsification performance depends on the molecular structure of sugar beet pectin, and the molecular structure is closely related to the extraction method. This review summarizes the extraction methods of pectin, structure characterization methods and the current research status of sugar beet pectin-stabilized emulsions. The structural characteristics of sugar beet pectin (such as degree of methylation, degree of acetylation, degree of blockiness, molecular weight, ferulic acid content, protein content, neutral sugar side chains, etc.) are of great significance to the emulsifying activity and stability of sugar beet pectin. Compared with traditional hot acid extraction method, ultrasonic-assisted extraction, microwave-assisted extraction, subcritical water-assisted extraction, induced electric field-assisted extraction and enzyme-assisted extraction can improve the yield of sugar beet pectin. At the same time, compared with harsh extraction conditions (too high temperature, too strong acidity, too long extraction time, etc.), mild extraction conditions can better preserve these emulsifying groups in sugar beet pectin molecules, which are beneficial to improve the emulsifying properties of sugar beet pectin. In addition, the interfacial self-assembly behavior of sugar beet pectin induced by the molecular structure is crucial to the long-term stability of the emulsion. This review provides a direction for extracting or modifying sugar beet pectin with specific structure and function, which is instructive for finding alternatives to gum arabic.
Background
The aim of the present study was to investigate the effect of substrate conformational structure changes on the laccase-induced protein cross-linking. The effects of laccase amount, pH, and ferulic acid (FA) on the enzymatic cross-linking of substrate, Cyt C, were determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. High performance size exclusion chromatography, laser particle size analysis and isothermal titration calorimetry (ITC) were also applied to investigate the cross-linking product and enthalpy changes. Structural changes of Cyt C at different pH values were analyzed by ultraviolet-visible (UV-Vis), fluorescence, and circular dichroism (CD) measurements.
Results
Complete cross-linking, partial cross-linking, minute cross-linking, and no cross-linking occurred at pH 2.0, 4.0, 6.0, and 8.0, respectively. ITC analysis demonstrated that the enzymatic cross-linking of Cyt C was an endothermic process. The UV-Vis, fluorescence, and CD measurements exhibited that the tertiary structure of Cyt C was disrupted, and part of the α-helical polypeptide region unfolded at pH 2.0. The structural flexibilities decreased and the tertiary structure of Cyt C became increasingly compact with the increase in pH values from 4.0 to 8.0. The gradual changes in the structure of Cyt C at different pH values were in accordance with the cross-linking results of Cyt C catalyzed by laccase.
Conclusions
The results demonstrated that minute structure changes of substrate had a remarkable effect on the laccase-induced cross-linking. The findings promote the understanding of the substrate requirement of laccase in protein cross-linking and are instructive for the modulation of laccase-induced protein cross-linking.
In this study, we reported for the first time that the natural protein/polysaccharide hybrid nanoparticles (PPH NPs) with a diameter of ∼ 129 nm, originating from Lactobacillus plantarum fermented cheese whey, could act as green-based NPs for stabilizing Pickering emulsions. Characterizations of PPH NPs showed that the negative-charged PPH NPs were composed of ∼ 37.7% total protein and ∼ 7.3% polysaccharide bearing several functional groups, such as –OH, –NH, –COOH, etc.; and displayed excellent emulsifying capacity in preparing oil-in-water Pickering emulsions. The obtained emulsions exhibited gel-like behavior with excellent stability against the variation of pH, ionic strength, and temperature. Confocal observations showed that PPH NPs effectively adsorbed and anchored at the oil–water interface, thus creating the steric hindrance to inhibit droplet coalescence. This research is of importance in developing novel and biocompatible Pickering stabilizers with outstanding performance, as well as enable a versatile design of stable Pickering emulsions suitable for food industries.
Edible coatings can potentially reduce postharvest losses of tomatoes and preserve their health-benefit nutrients. We proposed that fish gelatin (FG) conjugated with bitter almond gum (BAG) may be suitable material for edible coating. Accordingly, coating dispersions were prepared with BAG, FG, or conjugates (1:2, 1:1, 2:1), and their effects were then investigated on the physicochemical and quality parameters of tomatoes during 28 days of storage at 20 °C. The occurrence of conjugation was assessed by scanning electron microscopy, Fourier transforms infrared spectroscopy, and rheological tests. The apparent viscosity and viscoelastic parameters improved proportionally to the BAG ratio in the conjugates. The conjugate-based coating maintained most tomato physicochemical parameters better than simple coating. Also, the conjugates preserved better sensory attributes and overall acceptability. However, the coating type did not affect pH, titrable acidity, and color indices apart from hue angle. Overall, BAG:FG (2:1) conjugate significantly delayed changes in firmness, lycopene content, titratable acidity, and limited weight loss and decay percentage to exhibit a protective performance for preserving tomatoes. Therefore, the conjugation FG with a higher BAG ratio can be promising to produce coating dispersion and maintain fruit quality during storability.
Wheat bran arabinoxylan-bovine serum albumin (WBAX-BSA) conjugates were prepared via enzymatic synthesis using horseradish peroxidase (HRP) and H2O2 as catalysts. The conjugates were characterized by ultraviolet-visible spectroscopy (UV-vis), high-performance size exclusion chromatography (HPSEC), scanning electron microscopy (SEM), and transmission electron microscope (TEM). The feasibility of its application in stable emulsions was also assessed. UV-vis results revealed that phenolic acid in WBAX and aromatic amino acids in BSA were implicated in the enzymatic synthesis of the WBAX-BSA conjugate with the optimal WBAX:BSA mass ratio of 3:2. HPSEC results confirmed the intermolecular interactions between WBAX and BSA and the molecular weight of WBAX-BSA (2673 ± 16 kg/mol) was higher than that of control groups. Compared with the WBAX/BSA physical complexes, the WBAX-BSA conjugates had higher apparent viscosity (0.08–0.24 Pa.s), denser structure, larger particle sizes (33.5 ± 5.7 nm), and improving emulsifying properties in oil in water (O/W) emulsion system under different environmental stresses. The preparation of the enzymatic conjugates not only provides novel O/W emulsion systems but also improves processed food manufacturing processes that require efficient emulsification.
In a previous study, κ-carrageenan (κ-Car) was conjugated with milk protein isolate (MPI) via the Maillard reaction in a wet-heating system, and the Maillard conjugate derived from the κ-Car/MPI mixture effectively improved the stability of oil-in-water emulsions. In this study, the κ-Car/MPI conjugate was used in ice cream products to investigate its potential as a stabilizer. The ice cream mixes stabilized by the κ-Car/MPI conjugate showed lower rheological parameter (ηa,10, K, G, and G″) values than those of ice cream mixes stabilized by the κ-Car/MPI mixture, and the physical stability of the ice cream mixes was improved by the addition of the κ-Car/MPI conjugate. No significant differences in the overrun and hardness values were observed between the κ-Car/MPI conjugate and κ-Car/MPI mixture in frozen ice creams. However, the ice cream with the κ-Car/MPI conjugate showed greater resistance to melting due to its improved water-holding capacity. These results suggest that ice cream with high melting resistance can be produced with the addition of the κ-Car/MPI conjugate. Thus, the κ-Car/MPI conjugate could be used as a novel stabilizer in ice cream products.
The morphology, stability, and rheological properties of water-in-oil-in-water (W1/O/W2) multiple emulsions (ME) stabilized by whey protein concentrate (W)-carboxymethylcellulose (C) soluble complexes (SCW/C) were evaluated. The interaction pH values (pHi) to generate SCW/C were established through zeta potential and turbidity determinations. Six ME variations were prepared using a constant weight ratio (WR) between W and C of 3:1 (where maximum interaction occurred) and by varying the way in which the biopolymers were adsorbed at the interface (layer-by-layer, LL, or pre-formed complex, PF) and pHi (3.7, 4.0 and 4.3). The ME initial volume-surface diameter (D3.2) of the oil droplets ranged from 2.4 to 3.2 μm, which on turn contained numerous flocculated water droplets. Higher viscoelastic moduli values (G′ and G″), more pronounced shear thinning behaviour and smaller changes in droplet size with storage time were displayed by ME made with a pHi value of 4.3, WR3:1, and LL biopolymers adsorption technique.
The efficient development and production of high quality emulsion-based products depends on knowledge of their physicochemical properties and stability. A wide variety of different analytical techniques and methodologies have been developed to characterize the properties of food emulsions. The purpose of this review article is to provide a critical overview of the most important properties of emulsions that are of interest to the food industry, the type of analytical techniques that are available to measure these properties, and the experimental protocols that have been developed to characterize the stability of food emulsions. Recommendations are made about the most suitable analytical techniques and experimental protocols needed to characterize the stability and properties of food emulsions.
Sugar beet pectin (SBP) was enzymatically modified by crosslinking ferulic acid groups using horseradish peroxidase (HRP). The purpose of the modification was to achieve maximum molecular weight while retaining reasonably good solubility of the SBP. Reaction conditions were optimized in terms of pH (5.0–7.0), H2O2 concentration (0.25–1.0 mM) and HRP dose (0.0017–0.0083 U/mL). A maximum molecular weight of 1.86 × 106 Da was obtained at pH = 6.5, H2O2 = 1.0 mM and HRP = 0.005 U/mL while also remaining good solubility. The emulsifying properties of the SBPs before and after modification were evaluated. The emulsion prepared using the modified SBP and medium chain triglyceride (MCT) showed improved stability during acceleration test at 60 °C for a period of 10 days, in comparison with the emulsion prepared with control SBP. The volume-weighted mean diameter D4, 3 after 10-day acceleration was 12.1 and 20.6 μm for emulsions stabilized with modified and control SBPs, respectively.
Peanut protein isolate (PPI) was glycated with gum Arabic for 3, 6 and 9 days respectively to study the effect of different degree of graft on the physical and structural properties of glycated films. As the glycation continued, the degree of graft of PPI-gum Arabic conjugates increased gradually, the degree of crosslinking between PPI and gum Arabic in films also increased. Compared to PPI films, glycated films had increased tensile strength, decreased water vapor permeability (WVP), but decreased elongation. As the glycation proceeded from 3 to 9 days, the tensile strength of glycated films decreased, the WVP and the elongation increased gradually. This phenomenon may be caused by the decreased crystalline and increased amorphous structure of glycated films with the glycation time, which was confirmed by X-ray diffractometry and scanning electron microscopy. Disulfide bonds were the predominant interactive forces involved in all film networks. The result suggested that as the glycation continued, the level of disulfide bonds in PPI-gum Arabic films reached equilibrium after 6 days glycation.
Based on layer-by-layer electrostatic deposition, orange oil bilayer emulsions stabilized with lactoferrin (LF)–soybean soluble polysaccharides (SSPS) and lactoferrin (LF)–beet pectin (BP) were prepared. The effect of environmental stresses (ionic strength, pH, freeze–thaw and light) on the physicochemical stability of primary and secondary emulsions was investigated. In the absence of anionic polysaccharides, orange oil emulsion was highly unstable and aggregated at pH 7–9 and NaCl of 0.1–0.5 M. The droplets in LF–SSPS coated emulsion were stable against aggregation at pH range of 3–10 and NaCl concentration less than 0.3 M, while the droplets in LF–BP coated emulsion were stable against aggregation at pH 4–9 and NaCl concentrations of 0–0.5 M. All the primary and secondary emulsions showed the instability after the freeze–thaw treatment and the stability could be improved in the presence of maltodextrin. During the light exposure (0.35 W/m2, 45 °C) for 8 h, the bilayer emulsions could protect key volatile compounds (decanal, octanal and geranial) from the oxidation compared with the primary emulsions. These results suggested that the layer-by-layer electrostatic deposition could improve the stability of LF-coated emulsion to environmental stresses.
Pectin from sugar beet is derived from the sugar beet pulp residue which results when sugar beets are processed for sucrose extraction. The sugar beet pectin has poor gelationability by the classic divalent-cation molecular mechanism because of a relatively high acetylation degree and short polygalacturonate backbone chain length. However, due to the feruloyl-substitutions on the side chains, the sugar beet pectic polysaccharides can be cross-linked via enzyme catalyzed oxidation. The enzyme kinetics and functionality of such oxidativelycross-linked sugar beet pectin, in relation to stabilizing emulsions has recently been investigated in model food emulsions. This paper reviews the pectin chemistry, enzymatic oxidative gelation mechanisms, interaction mechanisms of the sugar beet pectin with the emulsion droplets and explores how the gelation affects the rheology and stability of emulsion systems. The applied biotechnology concept of enzymatic gelation provides an array of opportunities for upgrading of low-value pectins for new food and non-food uses.
Heating the powder of whey protein isolate (WPI)-maltodextrin (MD) mixture, the Maillard reaction, improves thermal stability of WPI, but the effects of powder acidity have not been studied. In this work, solutions with WPI and MD were adjusted to pH 4–7 (m-pH) to obtain spray-dried powder that was glycated at 80 °C and 65% relative humidity for 1–4 h. The conjugates were evaluated for physicochemical properties. A higher m-pH and a longer glycation resulted in a darker color. The m-pH 6 treatment had the highest degree of glycation, lowest surface hydrophobicity, lowest isoelectric point, and highest denaturation temperature, which contributed to the best heat stability evaluated at 5% protein, pH 4–7 and 0–150 mM NaCl by heating at 138 °C for 1 min. The results indicate that adjusting WPI-MD mixture solution to pH 6.0 to prepare powder for glycation can reduce the color of protein ingredients while providing heat stability for transparent beverage applications.
Premix Membrane Emulsification (ME) with Shirasu Porous Glass membranes of 10 μm pore size enabled to produce oil-in-water (O/W) emulsions with different interfacial structures made of whey protein isolate (WPI) and carboxymethyl cellulose (CMC). Emulsions were stabilized by one interfacial layer, made of WPI (mono-layer emulsion) or 0.5 %wt WPI–0.25 %wt CMC complex (complex emulsion), or by two interfacial layers: one layer made of WPI and the second made of CMC (bi-layer emulsion) or WPI–CMC complex (sequential emulsion). Although the adsorption between the several layers was confirmed by Surface Plasmon Resonance (SPR), only O/W emulsions stabilized by one interfacial layer did not coalescence after homogenization. Mono-layer and complex emulsions were stable after emulsification with a 8.7 μm and 14.4 μm mean droplet size, respectively, although a significant amount of much smaller droplets contributed to increase droplet dispersion giving span values of 1.8 and 3.2 for mono-layer and complex emulsions, respectively.Regarding oxidation rate, TBARS in complex emulsions increased much faster than in mono-layer emulsions. Adsorption data at a hydrophobic interface and the electrical charge of the WPI–CMC complex suggested that it formed a thick (2.2 nm) but less dense (1.40 g cm−3) interface than WPI (2.59 g cm−3) with a negative charge able to attract any transition metal ion and promote lipid oxidation. Premix ME should be further optimized to obtain multi-layered interfaces with an external positive layer, e.g. made of WPI.
There is a great deal of interest in the Food Industry in the use of polysaccharides and proteins to stabilise oil-in-water emulsions and there is a particular interest nowadays in the use of polysaccharide–protein complexes. There are three classes of complexes namely; (a) naturally-occurring complexes in which protein residues are covalently attached to the polysaccharide chains as is the case, for example, with gum Arabic; (b) Maillard conjugates, which are formed by interaction of the reducing end of a polysaccharide with an amine group on a protein forming a covalent bond; and (c) electrostatic complexes formed between a polysaccharide and a protein with opposite net charge. This review sets out our current understanding of the nature of these different polysaccharide–protein complexes and their ability to stabilise oil-in-water emulsions.
Proteins are widely used as emulsifiers to facilitate the formation, improve the stability and provide specific physicochemical properties to oil-in-water emulsions. There have been a number of recent advances in the understanding of the ability of various types of proteins to provide these functional properties. This article focuses on the influence of solution composition (pH, ionic strength, sugars, polyols, surfactants, biopolymers) and environmental stresses (heating, chilling, freezing, drying) on the stability of globular protein stabilized emulsions.
The influence of pH and CaCl2 on the physical stability of dilute oil-in-water emulsions stabilized by whey protein isolate has been studied. The particle size, zeta potential and creaming stability of 0.05 wt% soy bean oil-in-water emulsions (d ≈ 0.53 μm) were measured with varying pH (3 to 7) and CaCl2 concentration (0 to 20 μM). In the absence of CaCl2 extensive droplet aggregation occurred around the isoelectric point of the whey proteins (4 < pH < 6) because of their low electrical charge, which led to creaming instability. Droplet aggregation occurred at higher pH when CaCl2 was added to the emulsions. The minimum concentration of CaCl2 required to promote aggregation increased as the pH increased. Aggregation was induced in the presence of CaCl2 probably because of the reduction in electrostatic repulsion between droplets, caused by binding of counter ions to droplet surfaces and electrostatic screening effects.
Soy whey protein isolate (SWPI)–fenugreek gum (hydrolyzed and unhydrolyzed) conjugates were prepared by Maillard-type reaction in a controlled dry state condition (60 °C, 75% relative humidity for 3 days) to improve emulsification properties. Fenugreek gum was partially hydrolyzed using 0.05 M HCl at 90 °C for 10 min (HD10), 30 min (HD30) and 50 min (HD50) to examine if molecular weight had an effect on the emulsifying properties. The formation of SWPI–fenugreek gum conjugates was confirmed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Measurements of particle size distribution and average particle size have shown that conjugation of SWPI–fenugreek gum at 60 °C for 3 days was enough to produce relatively small droplet sizes in oil-in-water (o/w) emulsions. A ratio of 1:3 and 1:5 of SWPI:fenugreek gum was more effective in stabilizing emulsion compared to 1:1 ratio. Unhydrolyzed fenugreek gum conjugates exhibited better emulsifying properties compared to partially hydrolyzed fenugreek gum conjugates. The order of the conjugates in lowering the particle size of emulsions was as follows: SWPI–unhydrolzed fenugreek gum > SWPI–HD10 > SWPI–HD30 > SWPI–HD50.
Laccase, an oxidative enzyme, was used to catalyze the hetero and homo covalent conjugation between ferulic acid in sugar beet pectin (SBP) and tyrosine in heated β-lactoglobulin (H_BLG). The conjugation of SBP and H_BLG was confirmed by peak position using size exclusion chromatography, multi angle laser light scattering, refractive index, and UV detection. H_BLG, pre-treated with laccase, eluted at an earlier volume with greater UV280 absorbance than non-laccase treated dispersions. Tyrosine decreased in H_BLG that contained laccase treated SBP samples. Heat enhanced exposure of tyrosine in BLG and improved conjugation with SBP by laccase. H_BLG·SBP conjugates with laccase had improved solubility than laccase untreated dispersions at pH values near the isoelectric point of BLG.
Extensive research has indicated that the electrostatic attraction between polysaccharides and proteins on the oil–water interface can improve the stability of emulsions. However, this electrostatic effect will be weakened or even eliminated as the solution pH or ionic strength of emulsions change, resulting in the shedding of the polysaccharide layer. We prepared primary oil-in-water emulsions at pH 7.0 using whey protein isolate (WPI) as an emulsifier and then beet pectin was added to form secondary emulsions. After the pH of emulsions was adjusted to 4.0 to promote electrostatic attraction between the beet pectin molecules and the protein-coated droplets, horseradish peroxidase was added to generate a cross-linked beet pectin coating. Results show that stable emulsions coated with WPI and cross-linked beet pectin interfaces could be formed. The sensitivity of the emulsions to the environmental stresses of pH changes, ions addition, thermal processing and freezing was also characterized in this work. Our results support the view that cross-linked beet pectin improves the stability of emulsions and is superior to simple deposition on the surface of lipid droplets. The interfacial engineering technology used in this study could be used to create food emulsions with improved stability to environmental stresses.
Soybean oil bodies are naturally coated by a layer of phospholipids and oleosin proteins, which protect them from in vivo environmental stresses. When oil bodies are incorporated into food products, they encounter new environmental stresses such as changes in pH, ionic strength, and temperature. Consequently, additional protection mechanisms are often needed to stabilize them. The purpose of this study was to determine whether soybean oil bodies could be stabilized by coating them with a layer of cross-linked anionic polysaccharide (beet pectin). The beet pectin layer was cross-linked via its ferulic acid groups using laccase (an enzyme that catalyzes the oxidation of phenolic groups). Oil body suspensions were prepared that contained 1 wt % oil and 0.06 wt % beet pectin at pH 7 and were then adjusted to pH 4.5 to promote electrostatic deposition of the beet pectin molecules onto the surfaces of the oil bodies. Laccase was then added to promote cross-linking of the adsorbed beet pectin layer. Cross-linked pectin-coated oil bodies had similar or better stability than uncoated oil bodies to pH changes (3 to 7), NaCl addition (0 to 500 mM), and freeze-thaw cycling (-20 °C for 22 h; +40 °C for 2 h). These pectin-coated oil bodies may provide a convenient means of incorporating soybean oil into food and other products.
The emulsification performance, stability and competitive adsorption of two natural food emulsifiers, sugar beet pectin (SBP) and hydroxypropyl methylcellulose (HPMC) have been investigated. Both can reduce the surface tension and emulsify oil in water. However, due to their different structure and conformation they operate via different mechanisms. Using 15% middle chain triglycerides (MCTs) oil, the amounts of SBP and HPMC adsorbed in emulsions made with these individually and in mixtures were determined. The interfacial concentration (Γ) for SBP stabilized emulsion was ∼1.25mg/m(2) and for HPMC 3.5mg/m(2). The higher adsorption of HPMC was due to multilayer adsorption, whereas SBP adsorbed as a monolayer. Competitive adsorption between SBP and HPMC was also investigated. When the HPMC concentration approached that of adsorbed SBP, the effect of HPMC became dominant and at 1.5wt.% controlled the behavior of the mixed emulsions, which were then almost independent of SBP. The minor role of SBP was mainly to decrease the proportion of large droplets in the emulsion. A model to describe the competitive adsorption between SBP and HPMC is proposed.
Protein–polysaccharide interactions play an essential structure-controlling role in foods and biomaterials. Turbidity and electrophoretic mobility measurements were used to investigate the formation of soluble and insoluble complexes between pea protein isolate (PPI) and the cationic polysaccharide, chitosan (Ch) as a function of pH and biopolymer mixing ratio (1:1–20:1 PPI–Ch). In addition, pH-induced conformational changes of PPI upon complexation with Ch were studied by fluorometry. As the PPI–Ch mixing ratio increased from 1:1 to 12.5:1, critical structure forming events (i.e., those associated with the formation of soluble and insoluble complexes) shifted to higher pHs, and progressively behaved similar to those for PPI alone. At biopolymer ratios > 15:1, mixed systems resembled that of PPI alone. Changes to the tertiary conformation of PPI upon complexation with Ch at a 7.5:1 biopolymer ratio were found to occur at pH 6.2, corresponding to the presence of insoluble complexes.
The emulsifying properties of sugar beet pectin (SBP) were investigated in relation to its molecular structure. SBP has been subjected to an enhancement process, and this material was here compared with conventional non-enhanced SBP. The oil-in-water emulsification properties of both were compared at 1.5% concentration at pH 3.25, using 15% middle-chain triglyceride as the oil phase. Their emulsification behavior after various enzyme treatments decreased in the order: protease > arabinanase/galactanase mixture > polygalacturonase. The enzyme treatment also decreased the molecular weight of SBP. Protease degraded the high molecular weight carbohydrate–protein complex. Arabinanase/galactanase mixture was more effective in decreasing the emulsification performance than polygalacturonase. The results confirm the key role of protein as the anchor for the oil droplets and identify also the contribution of the neutral lateral chains in stabilizing emulsions by forming a hydrated layer. Protein also aggregates, which functions as a linker for the association of the carbohydrate chains consequent to the enhancement process.Graphical abstractCorrelation plot of experimental and calculated pEC50 elucidates that almost all samples are uniformly distributed in a straight line around 45° origin. 3D-HoVAIF can illustrate structural feature of compounds.
In a previous study (Langmuir 28 (2012) 10164-10176.), we investigated the complexation of bovine serum albumin (BSA) with sugar beet pectin (SBP). A pH-composition phase diagram was established and structural transitions in relation to the phase diagram during complexation were identified. The present study examines the implications of these interactions on the emulsifying performance of BSA/SBP mixtures. Middle-chain triglycerides (MCTs) in water emulsions were prepared using conditions corresponding to different regions of the phase diagram. At high pHs and in the stable region of mixed individual soluble polymers where complexation is absent, there is no improved emulsifying performance, compared with the individual protein and polysaccharide. For these mixtures, the emulsion characteristics are controlled by the major component in the solutions, as determined by the competitive adsorption of the two components at the oil-water interface. At low pHs and low BSA/SBP ratios, and so mainly within the stable region of intramolecular soluble complexes, BSA/SBP mixtures greatly improve the stability of emulsions. Here, stabilisation is controlled by the cooperative adsorption of the two components at the oil-water interface. Through electrostatic complexation BSA promotes the adsorption of SBP on to interfaces to form a thick steric layer around emulsion droplets and thus providing better stability. At low pHs and high BSA/SBP ratios, that is, mainly within the unstable region of intermolecular insoluble complexes, emulsions prepared are extremely unstable due to bridging flocculation between emulsion droplets.
Conditions (pH, temperature, time) for the extraction of sugar beet pulp pectins were studied on a laboratory scale and transposed into a pilot plant. Good yields (∼ 14%) of pectins are obtained if the pulp is treated at pH 1.0, 85°C for 1 hr. The characteristics of the pilot extracted pectins are very close to those of the laboratory ones, except for a lower molecular weight (∼30,000 daltons). Their physicochemical properties confirm their poor gelling ability.
Proteins play an important role as macromolecular surfactants in foam and emulsion-type food products. The functioning of proteins in these applications is determined by their structure and properties in the adsorbed layers at air-water and oil-water interfaces. In addition, because typical food proteins are mixtures of several protein components, interaction between these components in the adsorbed layer also impacts their ability as surfactants to stabilize dispersed systems. In this paper, recent progress in our understanding of the molecular mechanisms involved in the formation and stability of protein-stabilized foams and emulsions has been reviewed.
The complexation between bovine serum albumin (BSA) and sugar beet pectin (SBP) was studied in situ by coupling glucono-δ-lactone (GDL) induced acidification with dynamic light scattering and turbidity measurements. Individual measurements at specific pHs and mixing ratios were also carried out using zeta potentiometry, gel permeation chromatography-multiangle laser light scattering (GPC-MALLS), and isothermal titration calorimetry (ITC). These investigations together enabled the establishment of a phase diagram of BSA/SBP and the identification of the molecular events during protein/polysaccharide complexation in relation to the phase diagram, which showed five regions: (I) a stable region of mixed individual soluble polymers, (II) a stable region of intramolecular soluble complexes, (III) a quasi-stable region of intermolecular soluble complexes, (IV) an unstable region of intermolecular insoluble complexes, and (V) a second stable region of mixed individual soluble polymers, on lowering pH. We found for the first time that the complexation could take place well above the critical pH(c), the value that most previous studies had regarded as the onset occurrence of complexation. A model of structural transitions between the regions was proposed. The borderline between region II and region III represents the BSA/SBP stoichiometry for intramolecular soluble complex at a specific pH, while that between region III and region IV identifies the composition of the intermolecular insoluble complex. Also studied was the effect of NaCl and CaCl(2) on the phase diagram and structural transitions.
The present study compares the emulsifying properties of sugar beet pectin (SBP), soybean soluble polysaccharide (SSPS), and gum arabic (GA) in oil-in-water (O/W) emulsions. Emulsifying properties of each hydrocolloid were evaluated in terms of the emulsion droplet-size distribution, adsorption behavior at the oil–water interface, and the zeta potential. The standard emulsion contained 15 w/w% medium-chain triglyceride as the oil source and was processed with two passes through a high-pressure homogenizer at 50 MPa. The surface-volume mean diameter d3,2 of the emulsions (pH 3.0) was equilibrated at <1.0 μm when the concentration of each hydrocolloid was equal to or higher than 1.5%, 4.0%, and 10.0% for SBP, SSPS, and GA, respectively, where the apparent shear viscosities of the emulsions at 10 s−1 were almost equivalent (30–35 mPa s). At these critical concentrations, the interfacial concentration of each hydrocolloid was in the order: SBP<SSPS<GA. Thus, SBP required the smallest amount to cover the surface of the oil droplets and to activate the interface. The zeta potential of the emulsions was in the order: GA<SSPS<SBP, indicating that electrostatically SBP was the most effective in stabilizing the emulsions. This was not compatible with the change in the d3,2 upon storage, however, indicating that steric factors have a more important effect on the emulsion stability. The effect of pH and salts on the emulsifying properties of each hydrocolloid was also compared.
Citrus pectin and beet pectin are able to reduce the interfacial tension between an oil phase and a water phase and can be efficient for the preparation of emulsions. Investigations were made to evaluate the effect of various parameters of pectin on its emulsifying capacity. Orange and rapeseed oils emulsions were prepared with pectin as an emulsifier. They were then separated by centrifugation and the pectin fraction remaining in the aqueous phase was analyzed. It was found that the molecular weight, protein and acetyl contents influenced significantly the emulsifying properties. It was observed that for both citrus and beet pectin, the fraction which became associated with the oil contained much more protein than the fraction in the aqueous phase. It is suggested that protein associated with the pectin played a key role in the stabilization of the emulsion. Our experiments indicated that depending on the pectin source, beet or citrus, only a limited quantity is adsorbed on the oil surface. The de-acetylated beet pectin maintained a good emulsifying ability but the chemically acetylated citrus pectin gave better results than the non-acetylated citrus pectin. It was inferred that acetyl groups could also contribute to emulsion stability. It is likely that they act by reducing the calcium bridging flocculation. A model is proposed to explain the emulsifying function of pectin.
The purpose of this study was to prepare and characterize stable oil-in-water emulsions containing oil droplets coated by multilayered biopolymer interfaces that were cross-linked by the enzyme laccase. Laccase is an enzyme that can cross-link ferulic acid groups present in beet pectin. Emulsions were prepared that contained 0.1 wt% corn oil, 0.05 wt% β-lactoglobulin, and 0.02 wt% beet pectin at pH 7. The emulsions were then adjusted to pH 4.5 to promote electrostatic deposition of the beet pectin molecules onto the surfaces of the protein-coated droplets. Laccase was then added to the emulsions to promote cross-linking of the adsorbed beet pectin molecules. We have shown that stable emulsions can be formed that are coated by cross-linked β-lactoglobulin–beet pectin interfaces, and that these emulsions have improved stability to NaCl addition over conventional one-layer or non-cross-linked two-layer emulsions.
The emulsifying properties of covalent complexes of maltodextrin (MD) with whey protein (WP) isolate have been investigated under both acidic and high electrolyte concentration conditions in systems containing medium-chain triglyceride oil or orange oil. Covalent coupling of protein to polysaccharide was achieved by dry-heat treatment of a protein+polysaccharide mixture for up to 2 h. It was confirmed by SDS-polyacrylamide gel electrophoresis that the WP does become directly linked to the MD. Analysis of droplet-size distributions has shown that this covalent linking of MD to WP leads to a very substantial enhancement in the protein emulsifying behaviour under both acidic and neutral conditions. Analogous dry-heating treatment of MD with soy protein does not have this positive effect. A whey protein–MD conjugate WP–MD19, made from MD (DE=19) of intermediate mean molecular weight (8.7 kDa), has been found to be capable of producing fine emulsion droplets (0.5–1 μm) with either triglyceride oil or orange oil. Optimized WP–MD19 conjugates can produce fine stable emulsions (20 vol% oil) at 2 wt% emulsifier content, whereas the equivalent emulsion made with gum arabic requires a 20–30 wt% level of emulsifier. A WP–MD19 conjugate of protein/polysaccharide ratio 1:2 or 1:3 is effective in stabilizing low-pH emulsions of a commercial flavour oil (containing a weighting agent) over a storage period of several weeks, with no visible precipitation or phase separation when mixed with colouring agents, either before or after extensive emulsion dilution.
Whey protein isolate (WPI) was chemically modified by vanillic acid in order to enhance its cross-linkability by laccase enzyme. Incorporation of methoxyphenol groups created reactive sites for laccase on the surface of the protein and improved the efficiency of cross-linking. The vanillic acid modified WPI (Van-WPI) was characterized using MALDI-TOF mass spectrometry, and the laccase-catalyzed cross-linking of Van-WPI was studied. Furthermore, the vanillic acid modification was compared with the conventional approach to improve laccase-catalyzed cross-linking by adding free phenolic compounds. A small extent of the vanillic acid modification significantly improved the cross-linkability of the protein and made it possible to avoid color formation in a system that is free of small phenolic compounds. Moreover, the potential application of Van-WPI as emulsifier and the effect of cross-linking on the stability of Van-WPI emulsion were investigated. The post-emulsification cross-linking by laccase was proven to enhance the storage stability of Van-WPI emulsion.
The ability of sugar beet pectin to stabilize 20% w/w limonene oil-in-water emulsions has been investigated. The size of the oil droplets as determined by laser diffraction measurements decreased from about 15 mum to about 6 mum when the pectin concentration increased from 0.05% to 2% w/w but leveled off thereafter, suggesting complete coverage of the oil droplets by the polymer at this optimum concentration. Isotherms for the adsorption of pectin, protein, and ferulic acid were constructed. The adsorption capacities at the oil-water interface of approximately 1.4 and approximately 0.2 mg/m (2) for protein and ferulic acid, respectively, compared to approximately 9.5 mg/m (2) for pectin revealed that the adsorbed fractions of the pectin sample were rich in protein (14.7%) and ferulic acid (2.1%) given that there were only 2.7% protein and 1.06% ferulic acid present in the whole pectin sample. Direct measurements on the adsorbed fraction recovered from the oil droplets via desorption with SDS confirmed that it contained 11.1% protein and 2.16% ferulic acid. The results suggest that one or both of these two functional groups adsorb onto the surface of the oil droplets and stabilize the emulsions. High molecular mass fractions adsorbed preferentially onto oil droplets during emulsification. As compared to those made with gum arabic, the emulsion samples made with sugar beet pectin samples exhibited similar (or even slightly higher) stability.
Stability and rheology of water-in-oil-in-water multiple emulsions made with proteinpolysaccharide soluble complexes
- T Funami
- M Nakauma
- S Ishihara
- R Tanaka
- T Inoue
- G O Phillips
- N Y Hern Andez-Marín
- C Lobato-Calleros
- E J Vernon-Carter
Funami, T., Nakauma, M., Ishihara, S., Tanaka, R., Inoue, T., & Phillips, G. O. (2011).
Structural modifications of sugar beet pectin and the relationship of structure
to functionality. Food Hydrocolloids, 25(2), 221e229.
Hern andez-Marín, N. Y., Lobato-Calleros, C., & Vernon-Carter, E. J. (2013). Stability
and rheology of water-in-oil-in-water multiple emulsions made with proteinpolysaccharide soluble complexes. Journal of Food Engineering, 119(2), 181e187.
Comparison of sugar beet pectin, soybean soluble polysaccharide, and gum arabic as food emulsifiers. 1. Effect of concentration, pH, and salts on the emulsifying properties
- F Michel
- J F Thibault
- C Mercier
- F Heitz
- F Pouillaude
- M Nakauma
- T Funami
- S Noda
- S Ishihara
- S Alàassaf
- K Nishinari
Michel, F., Thibault, J. F., Mercier, C., Heitz, F., & Pouillaude, F. (1985). Extraction and
charcterization of pectins from sugar beet pulp. Journal of Food Science, 50(5),
1499e1500.
Nakauma, M., Funami, T., Noda, S., Ishihara, S., AlÀAssaf, S., Nishinari, K., et al.
(2008). Comparison of sugar beet pectin, soybean soluble polysaccharide, and
gum arabic as food emulsifiers. 1. Effect of concentration, pH, and salts on the
emulsifying properties. Food Hydrocolloids, 22(7), 1254e1267.