Preparation of milk protein isolate/κ-carrageenan conjugates by maillard reaction in wet-heating system and their application to stabilization of oil-in-water emulsions

The role of defatted hydrolyzed egg yolk powder in protecting DHA algal oil

This study comprehensively investigated DHA algal oil emulsions and microcapsules prepared with different egg yolk hydrolysates (DHYP). Dual-enzyme (phospholipase A1 and protease) treatment enhanced emulsion stability by boosting protein adsorption, reducing particle size, and increasing zeta potential. For microcapsules, EF-DUAL, treated with dual-enzymes, had improved solubility, dispersibility, and wall material compactness, effectively protecting DHA from oxidation. During accelerated storage, EF-DUAL had the lowest oxidation levels and maintained a high DHA retention rate of 22.08 % after 12 days at 60 °C, extending DHA algal oil's shelf life by 300 %. Linear regression analysis indicated that the oxidation of DHA algal oil followed first-order kinetics, whereas microcapsule powders exhibited higher zero-order coefficients. Overall, this study underscores the potential of DHYP, particularly dual-enzyme hydrolyzed egg yolk powder, as a wall material for DHA microencapsulation.

Microencapsulation using a novel wall material prepared via Maillard reaction-derived mung bean protein-peach gum conjugates to enhance stability and functionality of chia seed oil

This study investigated the potential of Maillard reaction products (MRPs) derived from mung bean protein isolate (MBPI) and peach gum (PG) conjugates as wall materials for microencapsulating chia seed oil (CSO). Four formulations (MMRP1%-4%) were prepared using spray-drying and compared to a commercial sample (CMMRP). The MMRP4% formulation exhibited the highest encapsulation yield (91 %) and encapsulation efficiency (96 %), along with favorable physical properties, including a spherical shape and smooth surface. All formulation showed significantly greater stability during storage at 4 °C compared to 25 °C. After 30 days of storage, the MMRP4% formulation exhibited significantly higher oxidative stability, as evidenced by lowest peroxide values (0.3 and 0.24 mEq O2/kg CSO at 4 °C and 25 °C, respectively). Furthermore, the MMRP4% formulation displayed the slowest decrease in DPPH radical scavenging activity, reaching 6.6 % at 4 °C and 10.4 % at 25 °C after 30 days, compared to 14.2 % and 20.9 % for CMMRP samples, correspondingly. Molecular dynamics simulations confirmed the effectiveness of MRPs as encapsulants for CSO. Overall, the results suggest that CSO microencapsulated with MRPs of MBPI-PG can be a valuable addition to various food products for long-term storage.

New insights on health benefits, interactions with food components and potential application of marine-derived sulfated polysaccharides: A review

Sulfated polysaccharides refer to polysaccharides containing sulfate groups on sugar units. In nature, sulfated polysaccharides are widely distributed in marine organisms, and the variation in sulfation sites, monosaccharide composition, and branched chain distribution among different species results in differences in the physicochemical properties and biological activities. From the latest perspective, this review summarized the types, structural characteristics, and potential health benefits of sulfated polysaccharides in marine foods. In recent years, marine-derived sulfated polysaccharides have been widely used as stabilizers and antimicrobial agents applied in nutraceutical delivery systems and food packaging, which depend on their interactions with food components. Hence, we outlined the non-covalent/covalent interactions of marine-derived sulfated polysaccharides with food components (e.g., proteins, polysaccharides, and polyphenols) as well as the application in food industry. Additionally, the prospects and potential development for sulfated polysaccharides are concluded, aiming to provide a deep understanding of marine-derived sulfated polysaccharides to promote the industrial application in food health.

A novel Pickering emulsion stabilized solely by agar-glycine Maillard conjugates

A novel Pickering emulsifier was developed through the Maillard reaction between acidolyzed agar and glycine. The resulting agar-glycine (Agar-Gly) Maillard product particles effectively stabilized a long-term Pickering emulsion at low pH (as low as 3) and medium oil content (40 %-50 %) with a particle concentration of 1 %. Microstructural analysis revealed that Agar-Gly particles adsorbed around the droplets, forming a typical O/W Pickering emulsion. The formation of a dense and regular three-dimensional gel network around the droplets was crucial in restricting droplet movement and ensuring emulsion stability. This stability was significantly superior to emulsions stabilized solely with agar or a mixture of agar and glycine (Agar+Gly), owing to synergistic effects between particle interfacial layers and spatial site resistance. Incorporating the Agar-Gly Maillard product into low-fat mayonnaise not only markedly reduces its greasiness but also provides consumers with a low-fat, healthy alternative. Furthermore, Agar-Gly used as a Pickering stabilizer, it offers an easy mode of application for agar that does not require dissolution at elevated temperatures. This provides a straightforward and promising avenue for the use of agar in the high-value 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.

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.

Conjugation prepared by wet-Maillard reactions improves the stability and properties of lutein and lycopene loaded nanoparticles

In this study, lutein and lycopene were encapsulated in plant protein (faba bean protein concentrate, (FPC))-carrageenan (Car) conjugates prepared by Maillard reaction in an aqueous media. The conjugation improved encapsulation yield that reached to 82.69% and 93.07%, for lycopene and lutein, respectively. The mean particle diameters for lutein loaded nanoparticles observed smaller in FPC-Car conjugates (66.60 nm) than FPC (71.49 nm). Scanning electron microscopy images showed that FPC-Car conjugates were more spherical and no fractures or fissures on the surface, revealing that wall materials provided better protection and retention for core materials. The diameter of lycopene nanoparticles coated with FPC remained constant between pH 3-4 and 7-9 but increased to 220 nm at pH 4-6. Even though the diameter of lutein nanoparticles coated with FPC remains steady between pH 5 and 9, increased to 953 nm at pH 3. The bioaccessibility of the lutein or lycopene samples encapsulated by FPC were found as higher than FPC-Car conjugates. These findings suggest that protein-polysaccharide conjugates could be used as a wall material to encapsulate lipophilic lutein and lycopene in order to improve their stability, property and bioaccessibility. As a result, FPC-Car conjugates may be an alternative for the formation of functional beverages as well as other nutraceutical products.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s13197-024-05976-4.

Agar-gelatin Maillard conjugates used for Pickering emulsion stabilization

A few protein- and polysaccharide-based particles have shown promising potential as stabilizers in multi-phase food systems. By incorporating polymer-based particles and modifying the wettability of colloidal systems, it is possible to create particle-stabilized emulsions with excellent stability. A Pickering emulsifier (AGMs) with better emulsifying properties was obtained by the Maillard reaction between acid-hydrolysed agar and gelatin. Laser confocal microscopy imaging revealed that AGMs particles can be used as solid emulsifiers to produce a typical O/W Pickering emulsion, with AGMs adsorbing onto the droplet surface to form a dense interfacial layer. Cryo-scanning electron microscopy analysis showed that AGMs self-assembled into a three-dimensional network structure, which prevented droplets aggregation through strong spatial site resistance, contributing to emulsion stabilization. These emulsions exhibited stability within a pH range of 1 to 11, NaCl concentrations not exceeding 300 mM, and at temperatures below 80 °C. The most stable emulsion oil-water ratio was 6:4 at a particle concentration of 0.75 % (w/v). AGMs-stabilized Pickering emulsion was utilized to create a semi-solid mayonnaise as a replacement for hydrogenated oil. Rheological analysis demonstrated that low-fat mayonnaise stabilized with AGMs exhibited similar rheological behavior to traditional mayonnaise, offering new avenues for the application of Pickering emulsions in the food industry.

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.

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.

Recovery and Utilization of Pea Albumins as Acidic Emulsion Stabilizer by Complexation with Dextran Sulfate

In this work, pea albumins (PAs) were efficiently recovered by complexation with dextran sulfate (DS), and the emulsifying ability and stability of PA/DS complexes were studied. The largest amounts of PAs (81.25%) were recovered at r = 5:1 and pH_max (pH 3.41) by forming insoluble complexes; and only soluble complexes were formed at r = 2:1 and over the whole pH range (2.0-7.0). The emulsions stabilized by PA/DS soluble complexes remained stable under acidic conditions due to the highly negatively charge (from -45.10 ± 0.40 to -57.23 ± 0.66 mV) and small particle size (0.168 ± 0.010-0.448 ± 0.004 μm), while emulsions stabilized by PAs alone generated a strong creaming and serum separation at pH 5 and 6. In terms of emulsifying stability, all PA emulsions and unheated PA/DS emulsions became unstable with different creaming index after 14 days storage. SDS-PAGE results showed that the interface adsorption proteins of unheated emulsions mainly consisted of PA1a, which was unfavorable to the stability of the interface. On the contrary, heat treatment (95 °C, 30 min) and complexation (PA/DS = 2:1) enhanced the adsorption of PA2 and lectin at the interface, inhibiting the aggregation of PA2 and lectin. This resulted in long-term stability of the PA/DS emulsions under acidic conditions.

Effect of Milk Protein Isolate/κ-Carrageenan Conjugates on Rheological and Physical Properties of Whipping Cream: A Comparative Study of Maillard Conjugates and Electrostatic Complexes

With increasing consumer demand for “clean label” products, the use of natural ingredients is required in the food industry. Protein/polysaccharide complexes are considered good alternatives to synthetic emulsifiers and stabilizers for formulating stable emulsion-based foods. Milk protein and carrageenan are widely used to improve the physical properties and stability of dairy food products. In a previous study, milk protein isolate (MPI) was conjugated with κ-carrageenan (κ-Car) in a wet-heating system through the Maillard reaction, and the Maillard conjugates (MC) derived from MPI and κ-Car effectively improved the stability of oil-in-water emulsions. Therefore, MPI/κ-Car conjugates were used in whipping cream as natural emulsifiers in this study, and the physical and rheological properties of whipping creams stabilized using MPI/κ-Car MC and MPI/κ-Car electrostatic complexes (EC) were investigated. The whipping creams stabilized with MPI/κ-Car MC have lower rheological parameters (η_a,50, K, G′, and G″) than those of whipping creams stabilized with MPI/κ-Car EC. Although the overrun value was slightly reduced owing to the addition of MPI/κ-Car MC, the stability of the whipped creams with MC was effectively improved due to enhanced water-holding ability by conjugation.

Fabrication and characterization of soy β-conglycinin-dextran-polyphenol nanocomplexes: Improvement on the antioxidant activity and sustained-release property of curcumin

In this study, glycated soy β-conglycinin (β-CG) stabilized curcumin (Cur) composites were fabricated by a unique reversible self-assembly character of β-conglycinin-dextran conjugates (β-CG-DEX). Intrinsic fluorescence and far-UV CD spectra revealed that glycation did not affect the self-assembly property of β-CG in the pH-shifting treatment. The structure of β-CG-DEX could be unfolded at pH 12.0 and reassembled during acidification (from pH 12.0 to 7.0). Meanwhile, β-CG-DEX-3d, which was incubated at 60 °C for 3 days, exhibited a high loading capacity (123.4 mg/g) for curcumin, which far exceeds that (74.90 mg/g) of β-CG-Cur. Moreover, the reassembled β-CG-DEX-3d-Cur showed eminent antioxidant activity of approximately 1.5 times higher than that of free curcumin. During the simulated gastrointestinal condition, compared with β-CG-Cur, β-CG-DEX-3d-Cur nanoparticles showed a more stable and sustained release of curcumin. Thus, β-CG-DEX has immense potential to become a new delivery carrier for hydrophobic food components by means of a self-assembly strategy.

Molecular structure and functional properties of glycinin conjugated to κ-carrageenan and guar gum: A comparative study

Molecular structure and functional properties of glycinin conjugated to κ-carrageenan and guar gum using a dry-heating method were comparatively analyzed. Glycosylation was confirmed by analyzing the degree of grafting, protein subunit composition, infrared absorption profile, and changes in contents of protein secondary structures. K-carrageenan was proven to possess a greater susceptibility to be grafted to glycinin than guar gum due to its relatively low molecular weight and negatively charged characteristics. The improvement of solubility by glycosylation with guar gum near the isoelectric point of glycinin was better than that by glycosylation with κ-carrageenan. Glycinin glycosylated with both polysaccharides exhibited enhanced emulsifying activity and stability. The enhanced apparent viscosity, elastic modulus, and viscous modulus also demonstrated that glycosylation promoted the appearance of stable elastic network structure. In summary, glycosylation with these two polysaccharides conferred glycinin superior emulsifying and rheological properties, and κ-carrageenan exhibited a better performance compared to guar gum.

Maillard-Type Protein-Polysaccharide Conjugates and Electrostatic Protein-Polysaccharide Complexes as Delivery Vehicles for Food Bioactive Ingredients: Formation, Types, and Applications

Due to their combination of featured properties, protein and polysaccharide-based carriers show promising potential in food bioactive ingredient encapsulation, protection, and delivery. The formation of protein–polysaccharide complexes and conjugates involves non-covalent interactions and covalent interaction, respectively. The common types of protein–polysaccharide complex/conjugate-based bioactive ingredient delivery systems include emulsion (conventional emulsion, nanoemulsion, multiple emulsion, multilayered emulsion, and Pickering emulsion), microcapsule, hydrogel, and nanoparticle-based delivery systems. This review highlights the applications of protein–polysaccharide-based delivery vehicles in common bioactive ingredients including polyphenols, food proteins, bioactive peptides, carotenoids, vitamins, and minerals. The loaded food bioactive ingredients exhibited enhanced physicochemical stability, bioaccessibility, and sustained release in simulated gastrointestinal digestion. However, limited research has been conducted in determining the in vivo oral bioavailability of encapsulated bioactive compounds. An in vitro simulated gastrointestinal digestion model incorporating gut microbiota and a mucus layer is suggested for future studies.

Application of protein-polysaccharide Maillard conjugates as emulsifiers: Source, preparation and functional properties

The protein-polysaccharide conjugates formed by Maillard reaction can be used as novel emulsifiers in the food industry. Proteins and polysaccharides have extensive sources, and their emulsifying properties are highly dependent on their structural features. The Maillard conjugates can be prepared from conventional and novel methods, and these methods have different advantages and limitations in industrial applications. After an appropriate glycation, the conjugates show some modified or enhanced functional properties, including solubility, emulsifying property, thermal stability, foaming capacity, and gelation property. However, the research on the structure-function relationship of both proteins and polysaccharides is limited. It is necessary to well understand the characteristics of these biopolymers, and select appropriate conditions to control the process of Maillard reaction. Overall, the Maillard conjugates show great potential as the emulsifiers and stabilizers in the emulsion system. This review introduces the sources and structural characteristics of commonly used proteins and polysaccharides for Maillard reaction, outlines the methods (dry-heating, wet-heating, electrospinning, ultrasound, pulsed electric field, and microwave) for preparing Maillard conjugates and focuses on the improved functional properties (solubility, emulsifying, foaming and thermal properties) and the potential mechanisms.

A Literature Review on Maillard Reaction Based on Milk Proteins and Carbohydrates in Food and Pharmaceutical Products: Advantages, Disadvantages, and Avoidance Strategies

Milk has two main components that have high nutritional value—milk protein (casein and whey protein), and lactose. These components are extensively used in various areas, especially in food, i.e., as sweeteners, stabilizers, functional food ingredients, nutritional fortifiers, etc. Non-enzymatic browning refers to a series of chemical reactions between sugars and proteins that make food more appetizing. Non-enzymatic browning reactions include degradation of ascorbic acid, lipid peroxidation, caramel reaction, and the Maillard reaction (MR). The MR, as one of the four non-enzymatic browning reactions, has been well studied and utilized in food fields. Milk protein and lactose, as two main components of milk, have high chemical activities; they are used as reactants to participate in the MR, generating Maillard reaction products (MRPs). The MR involves a condensation reaction between carbonyl groups of various sugars and amino groups of amino acids/proteins. These MRPs have different applications in various areas, including food flavor, food oxidation resistance, drug carriers, etc. This work presents the positive and negative effects of the MR, based on the two main components of milk, used in food and medicine, as well as avoidance approaches to prevent the occurrence of negative effects.

Low Molecular Weight Kappa-Carrageenan Based Microspheres for Enhancing Stability and Bioavailability of Tea Polyphenols

Tea polyphenols (TP) are a widely acknowledged bioactive natural product, however, low stability and bioavailability have restricted their application in many fields. To enhance the stability and bioavailability of TP under certain moderate conditions, encapsulation technique was applied. Kappa–Carrageenan (KCG) was initially degraded to a lower molecular weight KCG (LKCG) by H2O2, and was selected as wall material to coat TP. The obtained LKCG (Mn = 13,009.5) revealed narrow dispersed fragments (DPI = 1.14). FTIR and NMR results demonstrated that the main chemical structure of KCG remained unchanged after degradation. Subsequently, LK-CG and TP were mixed and homogenized to form LK-CG-TP microspheres. SEM images of the microspheres revealed a regular spherical shape and smooth surface with a mean diameter of 5–10 μM. TG and DSC analysis indicated that LK-CG-TP microspheres exhibited better thermal stability as compared to free TP. The release profile of LK-CG-TP in simulated gastric fluid (SGF) showed a slowly release capacity during the tested 180 min with the final release rate of 88.1% after digestion. Furthermore, in vitro DPPH radical scavenging experiments revealed that LK-CG-TP had an enhanced DPPH scavenging rate as compared to equal concentration of free TP. These results indicated that LK-CG-TP microspheres were feasible for protection and delivery of TP and might have extensive potential applications in other bioactive components.