Pea protein isolate-gum Arabic Maillard conjugates improves physical and oxidative stability of oil-in-water emulsions

Effects of phosphate, sodium, and potassium ions on the transacylation reaction between propylene glycol alginate and sodium caseinate

The transacylation reaction between sodium caseinate (NaCas) and propylene glycol alginate (PGA) forms covalent conjugates with improved functionalities, but the effects of ions are unknown. The objective of this study was to evaluate the effect of phosphate, sodium, and potassium ions on the degree of glycation (DOG) after reaction at pH 11.0 and 21 °C for 2 h. The highest DOG at 1:1 (w:w) NaCas/PGA as measured with the ortho-phthalaldehyde assay was observed at 10 mM salt, following the order of KH2PO4 > KCl > NaH2PO4 = NaCl, while DOG was similar at ≥25 mM salt. The stronger binding of sodium than potassium ions with NaCas led to the lower DOG based on measuring conductivity and 23Na nuclear magnetic resonance. The reaction improved the solubility of NaCas at pH 4.5. The findings can be used to increase the yield of covalent casein-alginate conjugates and thus casein functionalities.

Cysteine and dialysis mediated inhibition of dynamic changes in glycosylated egg white protein during storage

Glycosylation is commonly used to improve the solubility and functionality of egg white protein (EWP), but glycosylated EWP is prone to quality deterioration during storage. To enhance its storage stability, cysteine (Cys) addition and dialysis-based desugar treatment were applied to xylo-oligosaccharide (XOS) glycosylated EWP (GEW) in accelerated storage examinations. Both Cys addition and dialysis minimized changes in soluble protein content, color difference, and particle size during storage. Further, they inhibited the Maillard reaction and the accumulation of its intermediate products. Cys addition effectively maintained protein structures and prevented protein crosslinking. However, dialysis lost the filling and protective effect of free sugars, lowering the denaturation temperature of ovalbumin. Cys and dialysis effectively maintained the stability of emulsifying properties, while Cys better preserved gelation. Overall, both Cys addition and dialysis markedly enhanced the storage stability of GEW, with Cys proving to be more effective.

Recent progress in protein-based high internal-phase Pickering emulsions: Composition, stabilization, applications, and future trends

Protein-based high internal-phase Pickering emulsions (HIPPEs) have attracted widespread attention in recent years because they exhibit unique advantages for 3D printing and dysphagia food, including moist, soft, and creamy texture, good swallowing behavior, and excellent 3D printing effect. HIPPEs stability vastly influences its 3D printing accuracy, texture, and swallowing behavior. This review aims to comprehensively explore crucial factors influencing the formation and stability of HIPPEs, presenting reasonable strategies to enhance HIPPEs stability. Our emphasis lies in uncovering the relationship between protein-based particles' interfacial behavior, HIPPEs stability, and the application of HIPPEs on 3D printing and dysphagia food. Furthermore, the convergence of 3D printing and dysphagia foods expected to deepen, facilitating development of HIPPEs-based dysphagia food. Although application prospect of HIPPEs is very wide, looking ahead, there are many areas where further research is still required: (1) exploring more sources of protein fibrils, microalgae and insect proteins as Pickering particles to stabilize HIPPEs; (2) constructing mathematical model that unraveling the relationship between particles' interfacial behavior and HIPPEs stability; (3) combining dual-nozzle 3D printing with infill structure to modify the texture behavior and obtain more attractive appearance of HIPPEs-based dysphagia foods; (4) linking rheological behavior with oral processing and swallowing will be a research trend for exploring the texture and mouthfeel of dysphagia foods at different stages of oral processing; (5) developing evaluation system connected with oral processing behavior of dysphagia foods; (6) exploring the nutrition retention and texture behavior of dysphagia foods during 3D printing, post-processing, and chewing/swallowing process.

Pea protein isolate-wheat bran arabinoxylan glycated complex improves the physical stability and bioaccessibility of O/W emulsion

The developing of green plant based protein as excellent emulsifier to prepare stable O/W emulsion has become crucial in food processing. This study investigated the emulsification property enhancing of pea protein isolate (PPI) through glycation with wheat bran arabinoxylan (WBAX) to form a covalent complex (PPI-WBAX), the stability and the application in encapsulating β-carotene of the prepared PPI-WBAX emulsion. Results showed that glycation improved the emulsification property of PPI as evidenced by the increased emulsifying activity index (6.7 %) and emulsion stability index (232.7 %), and this was due to the excellent spatial structure that was beneficial for adsorption at the oil-water interface of PPI-WBAX complex formed by covalently linking the amino group of PPI to the carbonyl group at the end of WBAX, indicated by spectral results. The PPI-WBAX emulsion exhibited good physical stability upon exposure to different environmental stressors with the particle size and zeta-potential exhibiting non-significant changes and the oil droplets exhibiting uniform and small size. During the application, the PPI-WBAX emulsion exhibited high encapsulation (98.64 % ± 0.04 %) and retention rates (77.64 % ± 1.27 %) after storage for 28 days. In vitro digestion increased the lipid digestibility (94.06 % ± 0.45 %) and β-carotene bioaccessibility (32.51 % ± 1.39 %) of the PPI-WBAX emulsion.

Glycation-mediated pea protein isolate-curcumin conjugates for uniform walnut oil dispersion: enhancing oxidative stability and shelf life

BACKGROUND

Traditional methods for fabricating protein-polyphenol conjugates have not preserved the structural and functional integrity essential for the food industry effectively. This research introduces an advanced encapsulation methodology designed to overcome these limitations, with the potential to enhance the stability of edible oil matrices significantly, leading to improved preservation techniques and extended shelf life.

RESULTS

Glycated pea protein isolate-curcumin conjugates (gPPI-CUR) were developed, demonstrating a marked improvement in the oxidative stability of walnut oil (WO), a proxy for edible oil matrices. Characterized by a Z-average diameter of 158.37 nm and an encapsulation efficiency of 80.94%, these conjugates demonstrated exceptional performance in reducing lipid oxidation and aldehyde formation. Molecular docking analysis confirmed the formation of robust bonds with curcumin, thereby amplifying antioxidant activity. The uniform distribution of gPPI-CUR throughout the walnut oil matrix, as validated by confocal microscopy, ensured sustained bioactivity and mitigated the risk of localized oxidation. Electron spin resonance spectroscopy corroborated the superior antioxidant properties of the conjugates, which translated into a substantial 19-day increase in the shelf-life of the oil.

CONCLUSION

The gPPI-CUR conjugates enhanced the oxidative stability of walnut oil significantly, as demonstrated by the increased shelf life and reduced lipid oxidation. This study introduced an effective encapsulation method that improved the stability and extended the shelf life of edible oils, aligning with consumer demands for high-nutrition food products. The results indicate that the gPPI-CUR conjugates could serve as a promising antioxidant strategy for food preservation, offering a practical approach to enhance food quality and safety. © 2025 Society of Chemical Industry.

Gum Arabic-protein coacervation: Recent advances for improved functionality and food applications

Gum Arabic (GA), a safe dietary fiber known for its ability to modulate healthy gut microbiota and biocompatibility, is highly intriguing for coacervation with several classes of proteins. Coacervation between GA and proteins has gained significant interest for a range of food applications, particularly for encapsulation, emulsification, thermal stability, and sustained release of bioactive compounds. To date, the optimization process has preliminarily focused on pH and the biopolymer ratio. However, this alone is not sufficient to determine the strength of interactions and functionality. This review evaluates the conditions under which GA complexes with proteins, focusing on modifications in conjugation methods and structural changes in GA or proteins that enhance electrostatic interactions and improve functionality. The review highlights the potential of unexplored modified GA, which could improve coacervation with proteins, and explores its possible food applications, such as encapsulation and sustained release of bioactives, probiotic viability, edible packaging, 3D-printed foods, shelf stability, and gummy candies, illustrating the future growth of GA-based coacervates. It also addresses the digestibility, safety, regulations, limitations, and future prospects of GA-protein coacervates. In conclusion, the enhanced complexation of highly compatible GA with food proteins suggests promising scalability for various food products.

Effect of soybean phosphatidylethanolamine-tamarind gum Maillard conjugate on physicochemical stability of water-in-oil emulsions

Lipid oxidation hinders the development of water-in-oil (W/O) emulsions. This work aimed to determine the impact of soybean phosphatidylethanolamine (SP)/tamarind gum (TG) ratios on interface activity and anti-oxidant capacity of Maillard conjugates (MCs) in W/O emulsions. Results showed that grafting degree of MCs reached maximum with SP/TG ratio at 1:1 (43.5 %). Compared with SP and mixtures, interface activity (larger reduction of interfacial tension) and anti-oxidant capacity of MCs, especially with SP/TG = 1:1, were enhanced. The improvement of interface activity was owing to more stable adsorption at the interface caused by the increase of zeta potential and water contact angle as well as faster interface saturation benefited from broader steric network of TG moiety. The higher DPPH scavenging ability and ferric-reducing antioxidant power of MC were attributed to the combined effects of grafting degree, interface activity and molecule behavior of TG moiety. When the MC was added, the emulsion was observed smaller droplet size (1.3 μm), higher zeta potential (-73.5 mV) and lower contents of primary and secondary oxidation products (decreased by 70.9 % and 78.7 %, respectively). Hence, soybean phosphatidylethanolamine-tamarind gum-Maillard conjugate was effective to improve the physicochemical stability of W/O emulsions.

Maillard reaction conjugates of millet bran globulin and Arabic gum for curcumin encapsulation: Physicochemical characterization, storage stability, and in vitro digestion

In this study, millet bran globulin (MBG) and Arabic gum (AG) conjugates were prepared through the Maillard reaction (MR) and applied to curcumin-loaded Pickering emulsions. The effect of MR on MBG-AG conjugates (MBG-AG con) was evaluated by the degree of grafting (DG), the absorbance of intermediate reactants, and the browning index. The emulsifying properties of MBG-AG con with different DGs were assessed using the emulsifying activity index (EAI) and emulsifying stability index (ESI). Curcumin-loaded Pickering emulsions were prepared using optimized conjugates. Results indicated that MR enhanced the conjugates emulsifying properties, leading to improved emulsion performance. Compared to MBG, the optimized conjugates exhibited approximately 252.3 % and 167.1 % increases in EAI and ESI, respectively. The formation of MBG-AG con was confirmed through polyacrylamide gel electrophoresis, Fourier transform infrared, and fluorescence spectroscopy. Morphological changes before and after MR were observed through scanning electron microscopy. In comparison to MBG-stabilized emulsions, conjugate-stabilized emulsions exhibited smaller droplets, higher curcumin encapsulation efficiency (over 80 %), and better apparent viscosity. During simulated digestion, the bioavailability of curcumin reached 88.67 % in Pickering emulsions stabilized by 5 % conjugates. This study demonstrated the potential application of MBG-AG con prepared via MR in stabilizing Pickering emulsions, providing new theoretical insights into curcumin encapsulation.

Interfacial behavior and emulsifying properties of coconut protein glycated by polygalacturonic acid with different molecular weight

Glycosylation can be used to improve the emulsifying properties of protein by covalently binding with sugar. In this study, we prepared coconut protein (CP) -polygalacturonic acid (PA) conjugates by dry-heat method, studied the effect of PA with different molecular weight on the structure and functionality of CP, and characterized the interfacical behavior of CP at the oil-water interface to establish the relationship between interfacial behavior and emulsion stability. The results showed that different molecular weights of PA (28.4 ± 2.01 kDa, 20.3 ± 3.09 kDa, 16.3 ± 3.07 kDa, 11.6 ± 2.33 kDa) significantly affected the grafting degree between CP and PA (14.57 % ± 0.98 %, 53.74 % ± 0.1 %, 45.5 % ± 1.81 %, 36.54 % ± 0.38 %, respectively). The results of scanning electron microscopy (SEM) and Fourier infrared spectroscopy (FT-IR) confirmed the successful preparation of PA-CP conjugates. The dynamic interfacial tension of the conjugate was lowest (11.03 ± 0.07 mN/m) at the lowest PA molecular weight (11.6 ± 2.33 kDa), which increased with the increase of molecular weight. The diffusion, penetration and rearrangement rates of the conjugate were the highest when the molecular weight of PA was 20.3 ± 3.09 kDa. Compared to mixtures, conjugates tended to form a more elastic and stable interfacial film at the oil-water interface. In addition, the glycosylation reaction could improve the emulsion stability, resulting in smaller droplets size and higher zeta potential. With the decrease of molecular weight of PA, the emulsifying performance of CP was also improved. In conclusion, this work can further expand the application of coconut protein in the food industry and indicate the direction for further development of pectin with different molecular weights in the food industry.

Maillard-derived mung bean protein-peach gum conjugates: A novel emulsifier to improve stability, antioxidants, and physicochemical properties of chia seed oil nanoemulsion

This research is designed to enhance the physio-chemical properties, constancy, and antioxidant activities of water-in-oil (W/O) emulsions containing chia seed oil (CSO) by utilizing mung bean protein isolate (MBPI)-peach gum (PG) conjugates, which were created through the Maillard reaction (MR), as the emulsifying agents. The emulsions were prepared using MBPI-PG produced through the Maillard reaction (EMRP) at concentrations of 0.5 %, 1 %, and 1.5 %. Another set of emulsions, serving as control samples, was prepared using MBPI-PG without the MR (EC) at the same concentrations. The EMRP samples demonstrated optimum characteristics during storage over 30 days at 25 °C, particularly at 1 % concentration, including the droplet size (176.37 nm), PDI (0.3), zeta potential (-47.52 Mv), quantity of absorbed protein (63.48 %), creaming index (22.99 %), and viscosity compared to EC. The emulsions prepared with MRP exhibited significantly lower POV (1.45 mM/kg oil) and TBARS (59.17 mM/kg oil) formation rates than EC. The EMRP1% formulation displayed the lowest release of antioxidant compounds among all formulations, suggesting low release control during storage. Molecular docking results confirmed that adding EMRP1% to the CSO emulsion significantly improved its quality and stability. This emulsifier could hold significant promise for future advancements in the food industry.

Recent advances in the plant protein-polyphenol interactions for the stabilization of emulsions

Proteins from plant sources including legumes, cereals and oilseeds are gaining attention due to their suitability for sustainable production, functionality, and positive consumer perception. On the other hand, polyphenols (PPs) are receiving considerable attention as natural ingredients in the human diet due to their potent antioxidant and anti-inflammatory properties. Recent studies indicate that the emulsifying properties of plant proteins (PLPs) can be improved after modification through covalent and/or non-covalent interactions with PPs due to the changes in the conformation and/or the surface chemistry of the proteins. Complexes formed between PLPs-PPs can serve as innovative ingredients for developing novel food products with modified textural properties. Also, Pickering emulsions, multiple emulsions, multilayer emulsions, nanoemulsions, and high internal phase emulsions can be stabilized by such systems to deliver bioactive compounds. This paper reviews the most recent research on the PLP-PP interactions and their role in the stabilization of various emulsion-based systems. A special emphasis is given to modifying the structure and functionality of PLPs and PPs. The challenges and opportunities of applying PLP-PP interactions in emulsion-based systems are also highlighted.

Physicochemical stability and controlled release of vitamin D3-loaded emulsions stabilised by whey protein isolate-basil seed gum conjugates

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.

Combining heat treatment and conjugation between guarana extract and pea protein isolate to produce O/W emulsions loaded with vitamin D3

Growing interest in plant-based materials for stabilizing food emulsions is driven by the clean-label trend. Conjugating plant proteins with phenolic compounds from plant extracts enhances their techno-functionality and allows their use as stabilizers of emulsion-based systems. This study aimed to (i) combine heat treatment (HT) and conjugation with guarana extract (GE) to improve the emulsifying ability of pea protein isolate (PPI); (ii) encapsulate vitamin D3 (VD) in PPI/GE-stabilized emulsions; (iii) evaluate the potential of these formulations in improving VD retention during storage and in vitro bioaccessibility. The particles showed a size distribution ranging from 0.5 to 10 µm, depending on the processing sequence. Furthermore, HT on PPI dispersions followed by conjugation with GE led to microgels that stabilized emulsions during 30 days of storage at 25 °C. Also, the conjugates significantly improved VD retention, ranging from 74 to 100 %, after 30 days of storage at 25 °C, even in the presence of UV light. VD-loaded emulsions produced by PPI-GE conjugates showed higher bioaccessibility values (>65 %) compared to emulsions produced by PPI alone (∼58 %) and VD-incorporated sunflower oil (37 %). Given the above, the technological modification of PPI through conjugation with GE phenolic compounds and HT efficiently produced O/W emulsions loaded with VD, improving its bioaccessibility and tailoring a system with potential application in plant-based beverage and dessert formulations.

Improving the emulsifying properties and oil-water interfacial behaviors of chickpea protein isolates through Maillard reaction with citrus pectin

The limited adsorption capability of chickpea protein isolates (CPI) at the oil-water interface restricts its application in emulsions. This study aimed to improve the emulsifying properties and interfacial behaviors of CPI through Maillard reaction with citrus pectin (CP). The research findings showed that the covalent linking of CP with CPI caused the unfolding of the molecular structure of CPI, exposing more hydrophobic groups. Consequently, the CPI-CP conjugates exhibited improved emulsifying properties. Emulsions stabilized by CPI-CP conjugates after 12 h of glycosylation demonstrated the smallest droplet sizes (1.73 μm) and the highest negative zeta potentials (-54.7 mV). Glycosylation also improved the storage and environmental stability of these emulsions. Interfacial adsorption kinetics analysis revealed the lower interfacial tension (13.94 mN/m) and faster diffusion rates of the CPI-CP conjugates. Furthermore, interfacial dilatational rheology analysis indicated that the CPI-CP conjugates formed an interfacial layer with a higher viscoelastic modulus (33.214 mN/m) and predominant elastic behavior. The interfacial film of CPI-CP conjugates showed excellent resistance to amplitude and frequency variations, enhancing emulsion stability. Thus, this study demonstrates that moderate glycosylation enhances interfacial performances and improves emulsion stability of CPI, providing new insights into the mechanisms by which CPI stabilizes emulsions.

A comprehensive review on composition to application of pea protein and its components

Pea protein, a valuable plant-based protein source, is notable for its nutritional value, essential amino acids, and low allergenicity, making it widely applicable in food, medicine, and materials. It consists mainly of globulin and albumin, which influence its functional properties and applications. However, there is a lack of comprehensive reviews on its extraction methods, functional properties, modification techniques, and applications in food. This paper aims to fill these gaps by detailing pea protein composition, extraction methods, functional properties, and modification impacts while summarizing its food applications and proposing future research directions. The goal is to enhance pea protein's functionality and expand its applications through optimized extraction and advanced technology. By improving extraction techniques and adapting pea protein for better functionality, we aim to develop high-quality market applications, ensuring the growth and sustainability of the pea protein industry globally. This approach promises a flourishing future for pea protein, meeting global competition demands and driving industry advancement.

Enhancing the functionality of pea proteins by conjugation with propylene glycol alginate via transacylation reaction assisted with ultrasonication

Pea proteins lack the desirable functional characteristics for food and beverage applications. In this study, transacylation reaction assisted with ultrasonication was used to glycate pea proteins with propylene glycol alginate to enhance their functional properties. The reaction was carried out at pH 11.0 for different pea protein isolate: propylene glycol alginate mass ratios and time durations in a sonic bath at 40 °C. Glycation was confirmed in gel electrophoresis, and ultrasonication enhanced the glycation, with optimal degrees of glycation observed at 45 min reaction time and mass ratios of 2:1 (37.73%) and 1:1 (35.96%). The transacylation reaction increased random coil content of pea proteins by 28% and enhanced their solubility by 2.02 times at pH 7.0, water holding capacity by >50% at pH 7.0, foaming properties, emulsifying properties, and heat stability. This study offers a novel approach that can enhance functionality and applicability of pea proteins.

A comprehensive review on the recent trends in extractions, pretreatments and modifications of plant-based proteins

Plant-based proteins offer sustainable and nutritious alternatives to animal proteins with their techno-functional attributes influencing product quality and designer food development. Due to the inherent complexities of plant proteins, proper extraction and modifications are vital for their effective utilization. This review highlights the emerging sources of plant-based proteins, and the recent statistics of the techniques employed for pretreatment, extraction, and modifications. The pretreatment, extraction and modification approach to modify plant proteins have been classified, addressed, and the recent applications of such methodologies are duly indicated. Furthermore, this study furnishes novel perspectives regarding the potential impacts of emerging technologies on the intricate dynamics of plant proteins. A thorough review of 100 articles (2018-2024) shows the researchers' keen interest in investigating novel plant proteins and how they can be used; seeds being the main source for protein extraction, followed by legumes. Use of by-products as a protein source is increasing rapidly, which is noteworthy. Protein studies still lack knowledge on protein fraction, antinutrients, and pretreatments. The use of physical methods and their combination with other techniques are increasing for effective and environmentally friendly extraction and modification of plant proteins. Several studies explore the effect of protein changes on their function and nutrition, especially with a goal of replacing ingredients with plant proteins that have improved or enhanced qualities. However, the next step is to investigate the sophisticated modification methods for deeper insights into food safety and toxicity.

Proteins from Legumes, Cereals, and Pseudo-Cereals: Composition, Modification, Bioactivities, and Applications

This review presents a comprehensive analysis of plant-based proteins from soybeans, pulses, cereals, and pseudo-cereals by examining their structural properties, modification techniques, bioactivities, and applicability in food systems. It addresses the critical need for a proper utilization strategy of proteins from various plant sources amidst the rising environmental footprint of animal protein production. The inherent composition diversity among plant proteins, their nutritional profiles, digestibility, environmental impacts, and consumer acceptance are compared. The innovative modification techniques to enhance the functional properties of plant proteins are also discussed. The review also investigates the bioactive properties of plant proteins, including their antioxidant, antimicrobial, and antitumoral activities, and their role in developing meat analogs, dairy alternatives, baked goods, and 3D-printed foods. It underscores the consideration parameters of using plant proteins as sustainable, nutritious, and functional ingredients and advocates for research to overcome sensory and functional challenges for improved consumer acceptance and marketability.

Characterization and emulsifying ability evaluation of whey protein-pectin conjugates formed by glycosylation

Glycosylation is a method that enhances the functional properties of proteins by covalently attaching sugars to them. This study aimed at preparing three conjugates (WP-HG, WP-SBP, and WP-RGI) by dry heating method to research the influence of different pectin structures on the functional properties of WP and characterize properties and structures of these conjugates. The research results manifested that the degree of glycosylation (DG) of HG, SBP and RGI were 13.13 % ± 0.07 %, 23.27 % ± 0.3 % and 36.39 % ± 0.3 % respectively, suggesting that the increase of the number of branch chains promoted the glycosylation reaction. The formation of the conjugate was identified by the FT-IR spectroscopy technique. And SEM showed that WP could covalently bind to pectin, resulting in a smoother and denser surface of the conjugates. The circular dichroism analysis exhibited that the glycosylation reaction altered the secondary structure of WP and decreased the α-Helix content. This structural change in the protein spatial conformation led to a decrease in the hydrophobicity of protein surface. But the addition of pectin further regulated the hydrophilic-hydrophobic ratio on the surface of the protein, thus improving the emulsification properties of WP. In addition, the glycosylation could improve the stability of the emulsion, giving it a smaller droplet size, higher Zeta-potential and more stable properties. In a word, this study pointed out the direction for the application of different pectin structures in the development of functional properties of glycosylation products in food ingredients.

Study on the structural characteristics and emulsifying properties of chickpea protein isolate-citrus pectin conjugates prepared by Maillard reaction

Chickpea protein isolate (CPI) typically exhibits limited emulsifying properties under various food processing conditions, including pH variations, different salt concentrations, and elevated temperatures, which limits its applications in the food industry. In this study, CPI-citrus pectin (CP) conjugates were prepared through the Maillard reaction to investigate the influence of various CP concentrations on the structural and emulsifying properties of CPI. With the CPI/CP ratio of 1:2, the degree of graft reached 35.54 %, indicating the successful covalent binding between CPI and CP. FT-IR and intrinsic fluorescence spectroscopy analyses revealed alterations in the secondary and tertiary structures of CPI after glycosylation modification. The solubility of CPI increased from 81.39 % to 89.59 % after glycosylation. Moreover, freshly prepared CPI emulsions showed an increase in interfacial protein adsorption (70.33 % to 92.71 %), a reduction in particle size (5.33 μm to 1.49 μm), and a decrease in zeta-potential (-34.9 mV to -52.5 mV). Simultaneously, the long-term stability of the emulsions was assessed by employing a LUMiSizer stability analyzer. Furthermore, emulsions prepared with CPI:CP 1:2 exhibited excellent stability under various environmental stressors. In conclusion, the results of this study demonstrate that the glycosylation is a valuable approach to improve the emulsifying properties of CPI.

Physicochemical characterization and environmental stability of a curcumin-loaded Pickering nanoemulsion using a pea protein isolate-dextran conjugate via the Maillard reaction

This study investigated pea protein isolate (PPI) and dextran (DX) conjugates produced via the Maillard reaction as Pickering stabilizers for various food applications. The results found that as heating time increased (0-5 h), the grafting degree heightened. The PPI-DX conjugate exhibited a rough porous surface in contrast to native PPI, accompanied by changes in molecular weight and secondary structure. Additionally, the aggregation of low-solubility PPI was partially inhibited due to the contribution of increased solubility and reduced surface hydrophobicity by glycation. Curcumin-loaded Pickering nanoemulsions stabilized with PPI-DX had smaller droplets and higher curcumin encapsulation (greater than80 %) than PPI-stabilized nanoemulsions. PPI-DX adsorbed on the interface showed improved physical stability compared to PPI alone, even after various pH conditions and three heat treatments. The nanoemulsion stabilized with PPI-DX demonstrated improved apparent viscosity and dispersion stability. These findings highlight the effectiveness of PPI-DX conjugates as stabilizers for developing stable and functional Pickering nanoemulsions.

High internal phase emulsions stabilized by whey protein covalently modified with carboxymethyl cellulose: Enhanced environmental stability, storage stability and bioaccessibility

In this work, the effects of whey protein-carboxymethyl cellulose (WP-CMC) conjugates on the environmental stability, in vitro digestion stability, storage stability and bioaccessibility of high internal phase emulsions (HIPEs) were investigated. Compared to the HIPEs stabilized by the mixture of WP and CMC, the HIPEs stabilized by WP-CMC were less sensitive to environmental changes by particle size and zeta-potential, and showed better stability and bioavailability of pine nut oil as well as β-carotene during simulated gastrointestinal digestion. In addition, the inclusion function and pine nut oil oxidative stability of the HIPEs stabilized by WP-CMC were better during 16 days of storage than those of the pine nut oil and HIPEs stabilized by the mixture of WP and CMC, and also expressed higher storage stability of β-carotene. These results suggested that the conjugate-stabilized emulsions developed in this study have potential applications as protectors and carriers of liposoluble active ingredients.

Maillard reaction between high-intensity ultrasound pre-treated pea protein isolate and glucose: Impact of reaction time and pH on the conjugation process and the properties of conjugates

In this study, pea protein isolate was pretreated with high intensity ultrasound (HIUS) at 300 W for 5 min. The Maillard reaction (MR) between the pretreated sample (UPPI) and glucose were performed by heating (80 °C) of their aqueous dispersion at various time (0, 6, 12, 18, and 24 h) and pH (6.0, 8.0, 10.0, and 12.0). According to browning index and glucose depletion, the conjugation between UPPI and glucose through MR was not markedly accelerated compared to PPI. FTIR and intrinsic/extrinsic fluorescence spectroscopy showed that HIUS pretreatment could alter secondary and tertiary structures of PPI. HIUS pretreatment coupled with MR increased hydrophobicity and particle size of UPPI-glucose conjugates. Solubility of UPPI and PPI was improved after MR; but the increment of former was lower than the latter. This study suggests that HIUS pretreatment is an effective method to improve the solubility of PPI regardless of the subsequent MR.

Effect of various oligosaccharides on casein solubility and other functional properties: Via Maillard reaction

This study explored the improvement of casein (CN)'s properties by conjugating it with oligosaccharides, namely, fructooligosaccharide (FOS), galactooligosaccharide (GOS), isomaltooligosaccharide (IMO), and xylo-oligosaccharide (XOS) via Maillard reaction to identify the most optimal oligosaccharides and modification conditions. The degree of grafting was 30.5 ± 0.41 % for CN-FOS, 33.7 ± 0.62 % for CN-GOS, 38.9 ± 0.51 % for CN-IMO, and 43.7 ± 0.54 % for CN-XOS. With the degree of grafting rising, more oligosaccharides were conjugated, causing greater changes in CN properties. The CN-XOS underwent significant alterations, as the introduction of oligosaccharides led to a decrease in particle size by around 51 nm. Furthermore, the hydroxyl groups caused a reduction in surface hydrophobicity, which in turn decreased the proportion of hydrophobic groups. The solubility of CN-XOS increased significantly at pH 3, by approximately 30.99 %. Additionally, the conjugation of oligosaccharides substantially boosted the rates of DPPH, ABTS, and -OH radical scavenging by 4.61 times, 2.20 times, and 2.58 times, respectively, and also improved the thermal stability of the modified CN. Moreover, the process lowered the protein digestibility, possibly enhancing its applicability as an active substance transporter. This research offers additional theoretical backing for altering CN with oligosaccharides and implementing it in the food and pharmaceutical sectors.

Microfluidized hemp protein isolate: an effective stabilizer for high-internal-phase emulsions with improved oxidative stability

BACKGROUND

Hemp protein isolates (HPIs), which provide a well-balanced profile of essential amino acids comparable to other high-quality proteins, have recently garnered significant attention. However, the underutilized functional attributes of HPIs have constrained their potential commercial applications within the food and agriculture field. This study advocates the utilization of dynamic-high-pressure-microfluidization (DHPM) for the production of stable high-internal-phase emulsions (HIPEs), offering an efficient approach to fully exploit the potential of HPI resources.

RESULTS

The findings underscore the effectiveness of DHPM in producing HPI as a stabilizing agent for HIPEs with augmented antioxidant activity. Microfluidized HPI exhibited consistent adsorption and anchoring at the oil-water interface, resulting in the formation of a dense and compact layer. Concurrently, the compression of droplets within HIPEs gave rise to a polyhedral framework, conferring viscoelastic properties and a quasi-solid behavior to the emulsion. Remarkably, HIPEs stabilized by microfluidized HPI demonstrated superior oxidative and storage stability, attributable to the establishment of an antioxidative barrier by microfluidized HPI particles.

CONCLUSION

This study presents an appealing approach for transforming liquid oils into solid-like fats using HPI particles, all without the need for surfactants. HIPEs stabilized by microfluidized HPI particles hold promise as emerging food ingredients for the development of emulsion-based formulations with enhanced oxidative stability, thereby finding application in the food and agricultural industries. © 2023 Society of Chemical Industry.

Astaxanthin encapsulation in soybean protein isolate-sodium alginate complexes-stabilized nanoemulsions: antioxidant activities, environmental stability, and in vitro digestibility

BACKGROUND

Nanoemulsions (NEs) have been considered an effective carrier to protect environmentally labile bioactive compounds from degradation during food processing. Among the numerous types of NEs, biopolymer-stabilized NEs have gained much attention to achieve this function because of the extensive sources, biocompatibility, and tunability. Therefore, the antioxidant activities, environmental stability, and in vitro digestibility of astaxanthin (AST)-loaded soybean protein isolate (SPI)-alginate (SA) complexes-stabilized NEs (AST-SPI-SA-NEs) were investigated in this study.

RESULTS

The AST-SPI-SA-NEs exhibited an encapsulation efficiency of 88.30 ± 1.67%, which is greater than that of the AST-loaded SPI-stabilized NEs (AST-SPI-NEs) (77.31 ± 0.83%). Both AST-SPI-SA-NEs and AST-SPI-NEs exhibited significantly stronger hydroxyl or diphenylpicryl-hydrazyl radical-scavenging activities than the free AST. The formation of SPI-SA complexes strengthened the thermal, light, and storage stability of AST-SPI-SA-NEs with no apparently increasing mean diameter (around 200 nm). AST-SPI-SA-NEs also exhibited a better freeze-thaw dispersibility behavior than AST-SPI-NEs. AST-SPI-SA-NEs were more stable than AST-SPI-NEs were under in vitro gastrointestinal digestion conditions and exhibited a greater bioaccessibility (47.92 ± 0.42%) than both AST-SPI-NEs (12.97 ± 1.33%) and free AST (7.87 ± 0.37%). Hydrogen bonding was confirmed to participate in the formation of AST-SPI-SA-NEs and AST-SPI-NEs based on the molecular docking results.

CONCLUSIONS

The construction of SPI-SA-NEs is conducive to the encapsulation, protection, and absorption of AST, providing a promising method for broadening the application of AST in processed foods or developing novel ingredients of functional foods. © 2023 Society of Chemical Industry.

Synergistic formulation approach for developing pea protein and guar gum enriched olive oil-in-water emulsion gels as solid fat substitutes: Formulation optimization, characterization, and molecular simulation

This study aimed to optimize the formulation of olive oil-in-water (O/W) emulsion gels by incorporating Pea Protein (PP) and Guar Gum (GG) as alternative options for solid fats. The optimum rheological (consistency index, apparent viscosity, recovery) and texture (firmness) properties of the emulsion gels were obtained using a mixture of 2 % PP, 1 % GG, 60 % Olive Oil (OO), and 37 % Water (W). The blend of PP2/GG1 showed the highest results for recovery and firmness, 111.27 % and 33.89 g, respectively. PP/GG blend emulsion gels exhibited higher absolute ζ-potential values, ranging between -72.3 and -77.4 mV. The polydispersity index (PDI) ranged from 0.185 to 0.535, with the most uniform distributions found in the PP/GG blend emulsion gels. Strong phase separation resistance indicated strong stability of PP-GG complex emulsion gels. Higher PP concentrations decreased emulsion oxidation. FTIR and XRD research showed that PP and GG interact strongly, indicating good compatibility. The free binding energy of the most stable configuration of the molecules was -6.8 kcal mol-1, indicating a high affinity. PP interacted with GG through 9 amino acid residues, with notable residues being Asp 224, Thr 235, Ala 332, Ile 334, and Arg 336, and their respective interaction distances ranged between 2.69 Å and 3.87 Å.

Pulsed electric field enhances glucose glycation and emulsifying properties of bovine serum albumin: Focus on polarization and ionization effects at a high reaction temperature

Previous studies demonstrated that the non-thermal effects of pulsed electric fields can promote protein glycation below 40 °C, but it does not always enhance the emulsifying properties of proteins, such as in the bovine serum albumin/glucose model. Therefore, the aim of this study was to investigate the impact of non-thermal effects on the glucose glycation and emulsification properties of bovine serum albumin at 90 °C. The results of circular dichroism, surface hydrophobicity, and molecular dynamics simulations showed that the polarization effect increased the degree of glycation of bovine serum albumin-glucose conjugates from 12.82 % to 21.10 % by unfolding protein molecule, while the emulsifying stability index was increased from 79.17 to 100.73 compared with the control. Furthermore, the results of principal component analysis and Pearson correlation analysis indicated that the ionization effect and the free radicals generated by pulsed electric fields significantly (p < 0.05) inhibited browning and reduced free sulfhydryl content. This study demonstrated that pulsed electric fields combined with heating can prepare glycated proteins with good emulsifying properties in a short period of time and at temperatures lower than conventional heating while reducing energy consumption. This processing strategy has potential applications in improving the emulsifying performance of highly stable proteins.

Changes in the structure and functional properties of soybean isolate protein: Effects of different modification methods

Soybean protein isolate (SPI) is an important plant protein in food processing; however, its spherical structure prevents the exposure of its hydrophobic residues and affects its functional properties. In this study, we elucidate the effects of deamidation, phosphorylation, and glycosylation on the structure (Fourier-transform infrared spectroscopy, circular dichroism, fluorescence, and scanning electron microscopy) and functional properties (solubility, emulsifying activity index (EAI), and emulsifying stability index (ESI)) of SPI. The zeta potentials of the deamidated, phosphorylated, and glycosylated (DSPI, PSPI, and MSPI, respectively) samples decreased significantly (p < 0.05) relative to those of SPI. The functional properties of the modified SPI samples were improved, with MSPI-2 showing the best solubility (86.73 ± 0.34%), EAI (118.89 ± 0.73 m2/g), and ESI (273.33 ± 0.59 min). Moreover, the effects of the three modifications on the SPI functional properties increase in the order MSPI > PSPI > DSPI. These results provide a theoretical understanding the relationship between the modifications and SPI structure.

Co-delivery of hydrophobic β-carotene and hydrophilic riboflavin by novel water-in-oleic acid-in-water (W/OA/W) emulsions

Hydrophobic β-carotene and hydrophilic riboflavin offer a wide range of health benefits, but their limited stability and bioaccessibility pose challenges to their use in the food industry. This study developed a water-in-oleic acid-in-water (W/OA/W) emulsion. The effects of internal/external water phase emulsifiers were investigated on their microstructure, encapsulation efficiency, and stability. Only 0.05 wt% soybean-derived phosphatidylcholine was required as a lipophilic emulsifier to produce W/OA/W emulsions that can encapsulate both hydrophobic β-carotene and hydrophilic riboflavin. Compared to the commercial pea protein isolate (PPI), the PPI-xylooligosaccharide conjugate demonstrated superior performance as hydrophilic emulsifiers in stabilizing W/OA/W emulsions. The W/OA/W emulsion co-delivery system improved the thermal stability, light stability, and bioaccessibility of β-carotene, as well as the light stability of riboflavin. Overall, the W/OA/W emulsion holds great promise for application in natural food and for co-delivering hydrophobic and hydrophilic bioactive ingredients.

Development of quinoa (Chenopodium quinoa Willd) protein isolate-gum Arabic conjugates via ultrasound-assisted wet heating for spice essential oils emulsification: Effects on water solubility, bioactivity, and sensory stimulation

Quinoa protein isolate-gum Arabic (QPI-GA) conjugates were developed by ultrasound-assisted wet heating to improve the water solubility and bioactivity of spice essential oils (EOs) in this study. The optimal conditions for QPI-GA conjugates preparation were found to be: heating temperature of 72 ℃, ultrasound power of 450 W, and reaction time of 46 min. QPI-GA conjugates displayed significantly higher emulsifying efficiency and stronger tolerance to pH variation, high salt concentration, and storage than raw materials. The emulsifying efficiency of emulsions was also influenced by the pH and viscosity of EOs, zeta potential of the emulsion as well as the relative density and lipid/water partition coefficient (P) of EOs were the possible factors impacting the stability of EO emulsions. The water solubility, antioxidant ability, and antibacterial ability of tested EOs were improved after emulsification. Meanwhile, encapsulation with QPI-GA conjugates played a good effect on reducing the sensory stimulation of EOs.

Comprehensive structural and functional characterization of a new protein-polysaccharide conjugate between grass pea protein (Lathyrus sativus) and xanthan gum produced by wet heating

The purpose of this work was to use a controlled wet-heating process to promote Maillard reaction (MR) between grass pea protein (GPPI) and xanthan gum (XG), and then analyse structural, functional and antioxidant properties of the conjugate (GPPI-XGCs). During heating, the degree of glycation of all conjugated samples was raised (up to 37.43 %) and, after heating for 24 h, the lightness of the samples decreased by 24.75 %. Circular dichroism showed changes in secondary structure with lower content of α-helix and random coil in conjugates. XRD patterns showed that MR destroyed the crystalline structure of the protein. In addition, Lys and Arg content of the produced conjugates decreased by 16.94 % and 6.17 %, respectively. Functional properties including foaming capacity and stability were increased by 45.17 % and 37.17 %, and solubility reached 98.88 %, due to the protein unfolding driven by MR. GPPI-XGCs showed significantly higher antioxidant activities with maximum ABTS-RS value of 49.57 %. This study revealed how MR can improve GPPI's properties, which can aid the food industry in producing a wide range of plant-based foods. Especially, among other characteristics, the foaming properties were significantly improved and the final product can be introduced as a promising foaming agent to be used in food formulation.

Nonenzymatic glycation as a tunable technique to modify plant proteins: A comprehensive review on reaction process, mechanism, conjugate structure, and functionality

Plant proteins are expected to become a major protein source to replace currently used animal-derived proteins in the coming years. However, there are always challenges when using these proteins due to their low water solubility induced by the high molecular weight storage proteins. One approach to address this challenge is to modify proteins through Maillard glycation, which involves the reaction between proteins and carbohydrates. In this review, we discuss various chemical methods currently available for determining the indicators of the Maillard reaction in the early stage, including the graft degree of glycation and the available lysine or sugar, which are involved in the very beginning of the reaction. We also provide a detailed description of the most popular methods for determining graft sites and assessing different plant protein structures and functionalities upon non-enzymatic glycation. This review offers valuable insights for researchers and food scientists in order to develop plant-based protein ingredients with improved functionality.

Water-soluble fraction of pea protein isolate is critical for the functionality of protein-glucose conjugates obtained via wet-heating Maillard reaction

Wet-heating Maillard reaction (MR) has been applied to improve the function of proteins by conjugating with soluble carbohydrates. However, the impact of soluble solutes particularly in plant protein on the degree of MR and the properties of the corresponding conjugates has yet to be discussed. In this study, high-intensity ultrasound (HIUS) was utilized to pretreat commercial pea protein isolate in order to improve its solubility. Two different fractions including soluble fraction (SUPPI) and whole solution (UPPI) of HIUS treated PPI were conjugated with glucose (G) to prepare SUPPI-G and UPPI-G, respectively, over a course of 24 h wet-heating at 80 °C. Conjugation was confirmed by the degree of glycation, SDS-PAGE, FTIR, and intrinsic fluorescence analysis. Color change and glucose content analysis showed that the degree of MR was greater when using SUPPI rather than UPPI. The solubility of SUPPI-G was further improved by 24 h of MR while it remained unchanged for UPPI-G. The emulsifying activity index and foaming capability of SUPPI-G were similar to those of UPPI-G. Interfacial properties determined by dynamic adsorption and dilatational rheology at both oil-water and air-water interface suggested that insoluble fraction of UPPI is essential to make stable emulsions and foams. In conclusion, the proportion of soluble protein in PPI is critical to its wet-heating MR based conjugation with glucose and the solubility of the conjugates.

Ultrasonic and homogenization: An overview of the preparation of an edible protein-polysaccharide complex emulsion

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.

Improving the Physicochemical Stability of Soy Phospholipid-Stabilized Emulsions Loaded with Lutein by the Addition of Sphingomyelin and Cholesterol: Inspired by a Milk Fat Globule Membrane

The emulsifying performance of glycerophospholipids alone is inferior to proteins, etc., while the sphingomyelin (SM) and cholesterol (Chol) naturally existing in biological membranes could interact with glycerophospholipids to influence the polar lipid arrangement. Inspired by the natural membranes, the effect of SM and Chol on the physicochemical stability of soy phospholipid (SPL)-stabilized emulsions during storage or under environmental stresses was determined. The results indicated that the addition of SM and/or Chol could improve the storage stability of the emulsions and protective effect on lutein significantly (p < 0.05). Except for UV irradiation, the addition of Chol significantly improved the stability of the emulsions against acid, salt, and heat. The strong intermolecular hydrogen bonds and condensed assembly formed by SM and Chol contributed to the best stability of SPL + SM + Chol-stabilized emulsions. The results gave insight into improving the emulsifying properties of glycerophospholipids with SM and Chol.

Extrusion of casein and whey protein isolate enhances anti-hardening and performance in high-protein nutrition bars

Model high-protein nutrition bars (HPNBs) were formulated by incorporating whey protein isolate (WPI) and casein (CN) at various extrusion temperatures (50, 75, 100, 125, and 150 °C) with a protein content of 45 g per 100 g. The free sulfhydryl groups, amino groups, hardness, and microstructures of HPNBs were analyzed periodically at 37 °C over a storage period of 45 days. Specifically, sulfhydryl group, amino group and surface hydrophobicity of extruded whey protein isolate (WPE) and extruded casein (CE) were significantly reduced (P < 0.05) compared to those of unextruded protein. HPNBs formulated with WPE (HWPE) and CE (HWCE) exhibited a slower hardening rate compared to those formulated with unmodified protein. Moreover, the color difference, hardness and sensory score of HPNBs after 45 days of storage were used as indicators, and the results of the TOPSIS multiple index analysis indicated that HPNB formulated with WPI extruded at 150 °C possessed the best quality characteristics.

Behavior of protein-polysaccharide conjugate-stabilized food emulsions under various destabilization conditions

The sensitivity of protein-stabilized emulsions to flocculation, coalescence, and phase separation under destabilization conditions (i.e., heating, aging, pH, ionic strength, and freeze-thawing) may limit the widespread use of proteins as effective emulsifiers. Therefore, there is a great interest in modulating and improving the technological functionality of food proteins by conjugating them with polysaccharides, through the Maillard reaction. The present review article highlights the current approaches of protein-polysaccharide conjugate formation, their interfacial properties, and the behavior of protein-polysaccharide conjugate stabilized emulsions under various destabilization conditions, including long-term storage, heating and freeze-thawing treatments, acidic conditions, high ionic strength, and oxidation. Protein-polysaccharide conjugates are capable of forming a thick and cohesive macromolecular layer around oil droplets in food emulsions and stabilizing them against flocculation and coalescence under unfavorable conditions, through steric and electrostatic repulsion. The protein-polysaccharide conjugates could be therefore industrially used to design emulsion-based functional foods with high physicochemical stability.

Unraveling the role of germination days on the aroma variations of roasted barley malts via gas chromatography-mass spectrometry based untargeted and targeted flavoromics

Roasting imparts malts with an increased amount of hedonic aromas. However, the relationship between the production of roasted malts and the generation of characteristic malt aromas remains unclear. In this study, roasted barley malts (RM) were prepared from three consecutive germination days (3, 4, 5D), and the aroma profiles among RM and base malt were holistically compared via HS-SPME-GC-MS/O-based flavoromics. Furthermore, the wort color, free amino acids, reducing sugars, and fatty acids compositions were determined before-and-after roasting. Results showed that roasting could flatten variations of precursors regardless of germination days. Additionally, based on quantitation of 53 aromas, a PLS-DA model was applied to differentiate all malts by 17 aromas with VIP ≥ 1. As for aroma harmony, RM with 4D-germination outstood due to a pleasant nutty note with the highest sweet-to-nutty index of 0.8. This work answers how germination days would impact the aroma of RM for the first time.

Preparation of high complex concentration emulsion stabilized by soy protein/dextran sulfate composite particles

BACKGROUND

Soy protein isolate (SPI) could be used as an emulsifier to stabilize emulsions, while SPI is unstable under low acidic conditions. The stable composite particles of SPI and dextran sulfate (DS) could be formed by the electrostatic interaction at the pH was 3.5. And the SPI/DS composite particles were used to prepare the high complex concentration emulsion. The stabilization properties of high complex concentration emulsion were investigated.

RESULTS

Compared to uncompounded SPI, the particle size of SPI/DS composite particles was smaller at 1.52 μm, and the absolute value of the potential increased to 19.9 mV when the mass ratio of SPI to DS was 1:1 and the pH was 3.5. With the DS ratio increased, the solubility of the composite particles increased to 14.44 times of the untreated protein at pH 3.5, while the surface hydrophobicity decreased. Electrostatic interactions and hydrogen bonds were the main forces between SPI and DS, and DS was electrostatically adsorbed on the surface of SPI. The emulsion stability significantly enhanced with the increase of complex concentration (38.88 times higher than at 1% concentration), the emulsion average droplet size was the lowest (9.64 μm), and the absolute value of potential was the highest (46.67 mV) when the mass ratio of SPI to DS was 1:1 and the complex concentration of 8%. The stability of the emulsion against freezing was improved.

CONCLUSION

The SPI/DS complex has high solubility and stability under low acidic conditions, and the SPI/DS complex' emulsion has a well stability. This article is protected by copyright. All rights reserved.

Effects of glycation methods on the interfacial behavior and emulsifying performance of soy protein isolate-gum Arabic conjugates

Glycated conjugation of plant protein such as soy protein isolate (SPI) with saccharides is one popular strategy to modify the physicochemical characteristics of these plant protein resources, which may be affected by the glycation methods including dry-heating and wet-heating. In this study, the impact of these two glycation methods on the rheological and emulsifying properties of a binary system made by SPI-gum Arabic (GA) was studied. The results indicated that dry-heating conjugates had higher viscosity and more elastic characteristics than those wet-heating conjugates. The emulsifying properties of SPI-GA conjugates by different preparation routes were evaluated by various oil phases including eugenol, cinnamaldehyde and soybean oil. Overall, emulsions stabilized by dry-heating conjugates showed lower zeta-potential value than those with wet heating conjugates. The interfacial properties of these conjugates were compared using soybean oil emulsion as a model. Higher emulsifying ability and stability were obtained by emulsions with dry-heating conjugates, which was attributed to their more compact structures, higher protein adsorption capacity and thicker viscoelastic films formed at the interface, and therefore enhanced electrostatic repulsion between droplets. The findings in this study are useful for fabrication and utilization of protein-polysaccharide glycation conjugates as emulsifiers in functional foods.

Food protein glycation: A review focusing on stability and in vitro digestive characteristics of oil/water emulsions

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.

Recent Trends in Improving the Oxidative Stability of Oil-Based Food Products by Inhibiting Oxidation at the Interfacial Region

In recent years, new approaches have been developed to limit the oxidation of oil-based food products by inhibiting peroxidation at the interfacial region. This review article describes and discusses these particular approaches. In bulk oils, modifying the polarity of antioxidants by chemical methods (e.g., esterifying antioxidants with fatty alcohol or fatty acids) and combining antioxidants with surfactants with low hydrophilic–lipophilic balance value (e.g., lecithin and polyglycerol polyricinoleate) can be effective strategies for inhibiting peroxidation. Compared to monolayer emulsions, a thick interfacial layer in multilayer emulsions and Pickering emulsions can act as a physical barrier. Meanwhile, high viscosity of the water phase in emulsion gels tends to hinder the diffusion of pro-oxidants into the interfacial region. Furthermore, applying surface-active substances with antioxidant properties (such as proteins, peptides, polysaccharides, and complexes of protein-polysaccharide, protein-polyphenol, protein-saponin, and protein-polysaccharide-polyphenol) that adsorb at the interfacial area is another novel method for enhancing oil-in-water emulsion oxidative stability. Furthermore, localizing antioxidants at the interfacial region through lipophilization of hydrophilic antioxidants, conjugating antioxidants with surfactants, or entrapping antioxidants into Pickering particles can be considered new strategies for reducing the emulsion peroxidation.

Improving Pea Protein Emulsifying Capacity by Glycosylation to Prepare High-Internal-Phase Emulsions

Pea protein has been extensively studied because of its high nutritional value, low allergenicity, environmental sustainability, and low cost. However, the use of pea protein in some food products is hindered due to the low functionality of pea protein, especially as an emulsifier. High-internal-phase emulsions (HIPEs) are attracting attention because of their potential application in the replacement of hydrogenated plastic fats in foods. In this study, the use of glycated pea protein isolate (PPI) as an emulsifier to prepare HIPEs is proposed. The functionalization of a commercial PPI in two ratios of maltodextrin (MD) (1:1 and 1:2) via glycosylation (15 and 30 min), to act as an emulsifier in HIPEs, is investigated. HIPE properties, such as oil loss and texture, were evaluated and related to microstructural properties. Glycated-PPI-stabilized HIPEs showed high consistency, firmness, viscosity, and cohesiveness values; a tight and homogeneous structure; and physical stability throughout storage. The results showed that emulsions were more stable when using a 1:2 ratio and 30 min of heat treatment. However, the reaction time was more determinant for improving the textural properties when a 1:1 ratio was used for glycosylation than when a 1:2 ratio was used. Glycosylation with MD via the Maillard reaction is a suitable method to enhance the emulsifying and stabilizing properties of PPI.

Influence mechanism of polysaccharides induced Maillard reaction on plant proteins structure and functional properties: A review

Plant proteins have high nutritional value, a wide range of sources and low cost. However, it is easily affected by the environmental factors of processing and lead the problem of poor functionality. These problems of plant proteins can be improved by the polysaccharides induced Maillard reaction. The interaction between proteins and polysaccharides through Maillard reaction can change the structure of proteins as well as improve the functional properties and biological activity. The products of Maillard reaction, such as reductone intermediates, heterocyclic compounds and melanoidins have certain antioxidant, antibacterial and other biological activities. However, heterocyclic amines, acrylamide, and products generated in the advanced stage of the Maillard reaction also have a negative impact, which may increase cytotoxicity and be associated with chronic diseases. Therefore, it is necessary to effectively control the process of Maillard reaction. This review focuses on the modification of plant proteins by polysaccharide-induced Maillard reaction and the effects of Maillard reaction on protein structure, functional properties and biological activity. It also points out how to accurately reflect the changes of protein structure in Maillard reaction. In addition, it also points out the application ways of plant protein-polysaccharide complexes in the food industry, for example, emulsifiers, delivery carriers of functional substances, and natural antioxidants due to their improved solubility, emulsifying, gelling and antioxidant properties. This review provides theoretical support for controlling Maillard reaction based on protein structure.