Structure and functional properties of soy protein isolate-lentinan conjugates obtained in Maillard reaction by slit divergent ultrasonic assisted wet heating and the stability of oil-in-water emulsions

Preparation of Lutein Nanoparticles by Glycosylation of Saccharides and Casein for Protecting Retinal Pigment Epithelial Cells

Age-related macular degeneration (AMD), a leading cause of visual impairment in the aging population, lacks effective treatment options due to a limited understanding of its pathogenesis. Lutein, with its strong antioxidant properties and ability to mitigate AMD by absorbing ultraviolet (UV) rays, faces challenges related to its stability and bioavailability in functional foods. In this study, we aimed to develop delivery systems using protein-saccharide conjugates to enhance lutein delivery and protect adult retinal pigment epithelial (ARPE-19) cells against sodium iodate (NaIO3)-induced damage. Various saccharides, including mannose, galactose, lactose, maltose, dextran, and maltodextrin, were conjugated to casein via the Maillard reaction for lutein delivery. The resulting lutein-loaded nanoparticles exhibited small size and spherical characteristics and demonstrated improved thermal stability and antioxidant capacity compared to free lutein. Notably, these nanoparticles were found to be nontoxic, as evidenced by reduced levels of cellular reactive oxygen species production (167.50 ± 3.81, 119.57 ± 3.45, 195.15 ± 1.41, 183.96 ± 3.11, 254.21 ± 3.97, 283.56 ± 7.27%) and inhibition of the mitochondrial membrane potential decrease (58.60 ± 0.29, 65.05 ± 2.91, 38.88 ± 1.81, 42.95 ± 1.39, 23.52 ± 1.04, 25.24 ± 0.08%) caused by NaIO3, providing protection against cellular damage and death. Collectively, our findings suggest that lutein-loaded nanoparticles synthesized via the Maillard reaction hold promise for enhanced solubility, oral bioavailability, and biological efficacy in the treatment of AMD.

Fabrication of high-preformance emulsifier from conjugating maltodextrin onto myofibrillar protein peptide with microwave- ultrasound synergy

In this study, we systematically investigated the emulsifying capabilities of myofibrillar protein (MP)- and MP peptide (MPP)-based conjugates synthesized through intensification techniques: water bath (WB), microwave, ultrasound, and the combined ultrasound-microwave (UM) methods. Compared with WB, microwave, and ultrasound treatments, the combined UM treatment greatly promoted the glycation reaction because ultrasound and microwave mutually reinforced modification effects. The resultant conjugate structure tended to unfold with more flexible conformation and homogeneous morphology. Moreover, the emulsifying properties of conjugates developed with single and combined ultrasound-assisted glycation displayed substantial improvement, and pre-hydrolysis further enhanced these performances, as observed in the Principal Component Analysis as well. Remarkably, MPP grafted by maltodextrin with the assistance of a combined UM field produced the smallest and most uniform emulsion system, positioning it as the most efficient emulsifier among all the fabricated glycoconjugates. Our study highlighted the potential of synergistically applying ultrasound and microwave techniques to develop a well-performance glycation with an ideal conjugate structure, in which they would be associated into a strong film that provided the robust physical barrier, creaming stability, heat retention, and oxidation resistance. These findings offered a basis for better utilizing complex ultrasonic technology to develop novel and improved MP-based food products.

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.

Synergistic effect of residual sugar on freeze-thaw stability of high internal phase emulsions using glycosylated cod protein as interface stabilizer

Nowadays, glycosylated protein seems to be one of the most effective stabilizers for preparing freeze-thaw stabile emulsion; nevertheless, few papers mentioned the relationship between the residual free sugars after the glycosylation reaction and the freeze-thaw stability of high internal phase emulsions (HIPEs). Herein, glucose was used to prepare glycosylated cod proteins (GCPs). The synergistic effect was related to the grafting degree of GCP, and the amount of glucose added to prepare freeze-thaw stable HIPEs was reduced from 20% to 4% when the grafting degree of GCP increased from 0% to 31.58% (i.e. 12% GCP). This might be due to fewer ice crystals forming in water phase or less destruction of emulsion droplets by ice crystals. The obtained results in this study will allow developing freeze-thaw stable HIPEs or new frozen 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.

Physicochemical and functional characteristics of glycated collagen protein from giant salamander skin induced by ultrasound Maillard reaction

Chinese giant salamander skin collagen (CGSSC) was successfully conjugated with glucose (Glu)/xylose (Xy) by ultrasound Maillard reaction (MR) in nature deep eutectic solvents (NADES). The effects of ultrasound and reducing sugar types on the degree graft (DG) of MR products (MRPs), as well as the influence of DG on the structure and functional properties of MRPs were investigated. The results indicated that the ultrasound assisted could markedly enhance the MR of CGSSC, and low molecular weight reducing sugars were more reactive in MR. The ultrasound MR significantly changed the microstructure, secondary and tertiary structures of CGSSC. Moreover, the free sulfhydryl content of MRPs were increased, thus enhancing the surface hydrophobicity, emulsifying properties and antioxidant activity, which were positively correlated with DG. These findings provided theoretical insights into the effects of ultrasound assisted and different sugar types on the functional properties of collagen induced by MR.

Effect of ultrasonic assisted grafting on the structural and functional properties of mung bean protein isolate conjugated with maltodextrin through maillard reaction

Four different methods of maillard reaction including ultrasound (150 W, 10 min) assisted, classical wet heating (80 °C, 60min), moderate water bath heating (60°C, 12 to 30 h) and dry state method (60 °C, 79 % relative humidity and 48 h) were used to Mung bean protein isolate - Maltodexrtin conjugates (MPI-MD) preparation. The samples prepared under ultrasound and wet heating were chosen for further analysis according to degree of graft and UV-absorbance at 420 nm. Higher glycosylation at short time and lower browning were obtained under ultrasound treatment. Covalent attachment in conjugates confirmed by SDS-polyacrylamide gel electrophoresis. The structural analysis revealed prominent unfolding effect of ultrasound waves on the protein's molecules. The decrease of α-helix content was related to the exposure of buried amino group residues during reaction. Glycation of MPI under ultrasound caused changes in tertiary structure of protein and leads to decrease in the fluorescence intensity compared with native and wet heating treatments. FTIR spectra confirmed the conjugation of the MPI and MD and suggested that protein structure was changed and ultrasound promoted the graft reaction more than wet heating treatment. Conjugated MPI showed higher emulsification and solubility index than MPI, moreover the effect of ultrasonic waves on ameliorated functional properties was impressive than those for wet heating treatment. Overall, this study showed use of ultrasonication in maillard reaction was a suitable method for producing MPI- MD conjugates and improved the efficiency of graft reaction and functional properties of grafts.

Development and evaluation of anti-reflux functional-oral suspension raft composed of sodium alginate-mung bean protein complex

This study aimed to develop a sodium alginate (Na alginate) and mung bean protein (MBP) raft complex to improve gastric reflux symptoms. Na alginate and MBP complexes with different ratios (1:1, 2:1, and 3:1, respectively) were used for raft formulations through a wet Maillard reaction. Structural properties of raft strength, reflux resistance, intrinsic fluorescence emission spectroscopy, and Fourier transform infrared spectroscopy (FTIR) were investigated for rafts. The suspension 1:1 Na alginate/MBP with 0 h Maillard reaction time exhibited the lowest sedimentation volume among the suspensions. In contrast, 3:1 Na alginate/MBP with 6 h Maillard reaction time showed the highest sedimentation volume. Based on the results, the 3:1 Na alginate/MBP rafts had the best results, and the results were within acceptable limits. Functional properties, including antioxidant properties, the Helicobacter pylori inhibition assay, the pancreatic lipase inhibition assay, and angiotensin-converting enzyme (ACE) inhibition, were investigated for rafts. The Na alginate/MBP raft has similar characteristics to Gaviscon syrup and can be used for obesity, Helicobacter pylori infection, high blood pressure, and gastric reflux.

A novel strategy for improving the stability of myofibrillar protein emulsions at low ionic strength using high-intensity ultrasound combined with non-enzymatic glycation

Poor emulsification of myofibrillar proteins (MPs) limits the production of meat protein emulsion-type products, and it is related to the myosin self-assembles in low-salt settings. The effect of high-intensity ultrasound (HIU) pretreatment combined with non-enzymatic glycation on MP-stabilized emulsions in low-salt settings was investigated in this study, and the potential mechanism was revealed. The results indicated that, compared to using either HIU or glycation treatment alone, HIU pretreatment in combination with glycation significantly improves the physical stability of emulsions while increasing the distribution uniformity and reducing the droplet particle size from 18.05 μm to 2.54 μm (P < 0.05). Correspondingly, the emulsion prepared using this approach exhibited a relatively high absolute zeta potential (-23.58 mV) and a high interfacial protein content (38.78 %) (P < 0.05), promoting molecular rearrangement and forming a continuous and stable interfacial layer. HIU pretreatment combined with glycation could offer reinforced electrostatic repulsion and steric hindrance to depolymerize self-assembled filamentous polymers, thus enhancing the stability of droplets. Additionally, the thermal sensitivity of the glycated MPs pretreated by HIU was remarkably reduced, thus improving the thermal stability of the corresponding emulsions.

High-intensity ultrasound combined with glycation enhances the thermal stability and in vitro digestion behaviors of myofibrillar protein aqueous solution

The low thermal stability of myofibrillar proteins (MPs) is a technological barrier to them being applied in beverage formulas. In this study, we investigated the effect of high-intensity ultrasound (HIU) pretreatment combined with glycation on the thermal stability, structural characteristics, and in vitro digestion behavior of MPs in water. The results indicated that HIU pretreatment combined with glycation significantly inhibited thermal aggregation and reduced the particle size of MPs compared to using either HIU or glycation treatments individually. The grafting of dextran (DX) shielded the sulfhydryl (-SH) and hydrophobic groups and inhibited disulfide bond cross-linking and hydrophobic association. Moreover, HIU pretreatment facilitated the shielding effect of glycation by destroying the filamentous myosin structure and exposing the internal -SH and hydrophobic groups as well as the grafting sites, maximally inhibiting thermal aggregation. In addition, the smaller protein particles and more flexible structure caused by HIU pretreatment combined with glycation increased their binding affinity toward protease. Overall, these findings can promote the technological development of modulating the MP structure-digestion for formulating novel meat protein-based products.

Physicochemical and functional property of the Maillard reaction products of soy protein isolate with L-arabinose/D-galactose

BACKGROUND

Soy protein isolate (SPI) is widely used in the food industry because of its nutritional and functional properties. During food processing and storage, the interaction with co-existing sugars can cause changes in the structural and functional properties of SPI. In this study, SPI-l-arabinose conjugate (SPI:Ara) and SPI-d-galactose conjugate (SPI:Gal) were prepared using Maillard reaction (MR), and the effects of five-carbon/six-carbon sugars on the structural information and function of SPI were compared.

RESULTS

MR unfolded and stretched the SPI, changing its ordered conformation into disorder. Lysine and arginine of SPI were bonded with the carbonyl group of sugar. The MR between SPI and l-arabinose has a higher degree of glycosylation compared to d-galactose. MR of SPI enhanced its solubility, emulsifying property and foaming property. Compared with SPI:Ara, SPI:Gal exhibited better aforementioned properties. The functionalities of amphiphilic SPI were enhanced by MR, SPI:Gal possessed better hypoglycemic effect, fat binding capacity and bile acid binding ability than SPI:Ara. MR endowed SPI with enhanced biological activities, SPI:Ara showed higher antioxidant activities, and SPI:Gal exhibited stronger antibacterial activities.

CONCLUSION

Our work revealed that l-arabinose/d-galactose exhibited different effects on the structural information of SPI, and further affected its physicochemical and functional property. © 2023 Society of Chemical Industry.

Dynamic microfluidic-assisted transglutaminase modification of soy protein isolate-chitosan: Effects on structural and functional properties of the adduct and its antioxidant activity after in vitro digestion

In this study, soy protein isolate (SPI)-chitosan (CS) adducts were prepared by using dynamic microfluidic-assisted transglutaminase (TGase) modification. It was shown that the solubility and degree of binding of SPI-CS adducts prepared by dynamic microfluidic-assisted TGase modification were better. After the samples were treated twice at 400 bar, the degree of binding for SPI-CS adducts increased to 31.97 ± 1.31%, and the solubility increased to 66.25 ± 1.10%. With the increase of microfluidic pressure, the exposed free sulfhydryl groups increased, the particle size reduced, and the surface hydrophobicity first increased and then decreased. Under the action of the pressure generated by microfluidics, the structure of the protein in the SPI-CS adduct was unfolded and transformed from an ordered structure to a disordered one. The SPI-CS adducts prepared with assisted dynamic microfluidic treatment showed significantly higher ABTS radical scavenging rate, DPPH radical scavenging rate and reducing power after in vitro digestion compared with that of SPI-CS adducts prepared with TGase alone. This result indicated that appropriate dynamic microfluidic treatment improved the structural and functional properties of TGase-modified SPI-CS adducts and significantly increased the antioxidant activity after in vitro digestion.

Effect of soy protein isolate nanoparticles loaded with litsea cubeba essential oil on performance of lentinan edible films

Environmental issues caused by plastic packaging materials have gotten increasingly severe, and substantial research has been conducted on environmentally friendly active packaging materials. In this study, the Litsea cubeba essential oil loaded soy protein isolate nanoparticles (LSNPs) with appropriate particle size, high storage stability and salt solution stability were fabricated. The LSNPs with the highest encapsulation efficiency of 81.76 % were added into the lentinan edible film. The microstructures of the films were observed by scanning electron microscopy. The physical properties of the films were measured. The results show that the lentinan film with LSNPs in the volume ratio of 4:1 (LF-4) had the highest elongation at break of 196 %, the lowest oxygen permeability of 12 meq/kg, and good tensile strength, water vapor barrier property, antibacterial property, oxidation resistance and thermal stability. The study suggested that LF-4 film could inhibit the growth of bacteria and delay the oxidation of lipid and protein on beef surface for 7 d.

Maillard reaction-based conjugation of Spirulina protein with maltodextrin using wet-heating route and characterisation of conjugates

Spirulina protein concentrate (SPC) was extracted from Spirulina biomass and its structure and technofunctional properties were modified through Maillard reaction with maltodextrin (MD). Wet-heating route was adapted and Maillard reaction was controlled within initial to intermediate stage by avoiding or minimising the formation of melanoidins. A glycation degree of up to 29.1 % was achieved after reaction between SPC and MD, and molecular weight of the SPC increased accordingly. The solubility of SPC was improved only in the pH range around its isoelectric point after conjugation. The antioxidative property of the SPC-MD conjugate was also improved as the DPPH radical scavenging activity increased 19.7 to 30.2 %. Oil-in-water emulsion stabilised by SPC-MD conjugate produced at 6 h had significantly reduced droplet size, increased surface charge, and higher physical stability in temperature range 25-60 °C. The outcome of this research will help broaden the application of SPC in food as emulsifier and encapsulating shell material.

Characteristics and antioxidant properties of Harpadon nehereus protein hydrolysate-xylose conjugates obtained from the Maillard reaction by ultrasound-assisted wet heating in a natural deep eutectic solvents system

BACKGROUND

Harpadon nehereus is a high-protein marine fish. A valuable way to add value to H. nehereus is to convert it into protein hydrolysate. The Maillard reaction is an effective way to improve the functional properties of peptides and proteins, which are affected by many factors such as reactant concentration, water activity, pH, temperature, and heating time. However, the traditional Maillard reaction method is inefficient. The purpose of this study was therefore to explore the effect of the ultrasound-assisted wet heating method on the Maillard reaction of H. nehereus protein hydrolysate (HNPH) in a new-type green solvent - a natural hypereutectic solvent (NADES).

RESULTS

Harpadon nehereus protein hydrolysate-xylose (Xy) conjugates were prepared via a Maillard reaction in a NADES system using an ultrasound-assisted wet heating method. The effects of different treatment conditions on the Maillard reaction were studied. The optimized glycation degree (DG) of HNPH-Xy conjugates was obtained with a water content of 10%, a reaction temperature of 80 °C, a reaction time of 35 min, and an ultrasonic power level of 300 W. Compared with HNPH, the structure of HNPH-Xy conjugates were significantly changed. Moreover, the functional properties and antioxidant activity of HNPH-Xy were all superior to the HNPH.

CONCLUSIONS

An ultrasound-assisted wet-heating Maillard reaction between HNPH and Xy in the NADES system could be a promising way to improve the functional properties of HNPH. © 2023 Society of Chemical Industry.

Enhancing the foaming properties of brewer's spent grain protein by ultrasound treatment and glycation reaction

The denaturation state and relatively poor solubility of brewer's spent grain protein (BSGP) have limited its industrial application. Ultrasound treatment and glycation reaction were applied to improve the structural and foaming properties of BSGP. The results showed that all ultrasound, glycation, and ultrasound-assisted glycation treatments increased the solubility and surface hydrophobicity of BSGP while decreasing its zeta potential, surface tension and particle size. Meanwhile, all these treatments resulted in a more disordered and flexible conformation of BSGP, as observed by CD spectroscopy and SEM. After grafting, the result of FTIR spectroscopy confirmed the covalent binding of -OH between maltose and BSGP. Ultrasound-assisted glycation treatment further improved the free SH and S-S content, which might be due to -OH oxidation, indicating that ultrasound promoted the glycation reaction. Furthermore, all these treatments significantly increased the foaming capacity (FC) and foam stability (FS) of BSGP. Notably, BSGP treated with ultrasound showed the best foaming properties, increasing the FC from 82.22% to 165.10% and the FS from 10.60% to 131.20%, respectively. In particular, the foam collapse rate of BSGP treated with ultrasound-assisted glycation was lower than that of ultrasound or traditional wet-heating glycation treatment. The enhanced hydrogen bonding ability and hydrophobic interaction between protein molecules caused by ultrasound and glycation might be responsible for the improved foaming properties of BSGP. Thus, ultrasound and glycation reactions were efficient methods for producing BSGP-maltose conjugates with superior foaming properties.

Characterization and utilization of soy protein isolate-(-)-epigallocatechin gallate-maltose ternary conjugate as an emulsifier for nanoemulsions: Enhanced physicochemical stability of the β-carotene nanoemulsion

In this study, a ternary conjugate was prepared by covalent bonding of protein, polysaccharide, and polyphenol via ultrasound and the Maillard reaction. Subsequently, the β-carotene nanoemulsion was prepared with the soy protein isolate-(-)-epigallocatechin gallate-maltose (SPI-EGCG-maltose) conjugate as the emulsifiers via ultrasound. The SPI-EGCG-maltose conjugate showed superior solubility, emulsification and foaming properties at 4 h reaction time. Meanwhile, the retention rates of β-carotene in the nanoemulsion after 30 d of storage, 8 h of light, and 55 °C of heat were >60%, >75%, and >60%, respectively. Furthermore, ultrasound treatment at 500 W for 10 min produced an inhibitory effect on the degradation of β-carotene. This study indicates that the nanoemulsion based on the ternary conjugate can effectively inhibit the β-carotene degradation by the external environment and prevent the oxidation and degradation of β-carotene in the nanoemulsion.

Changes in the functional properties of casein conjugates prepared by Maillard reaction with pectin or arabinogalactan

The aim of this study was to prepare conjugates of casein (CA) with pectin (CP) or arabinogalactan (AG) by the Maillard reaction (wet-heating) and to investigate the effects of CP or AG on the structural and functional properties of casein. The results indicated that the highest grafting degree of CA with CP or AG was observed at 90 °C for 1.5 h or 1 h, respectively. Secondary structure showed that grafting with CP or AG reduced the α-helix level and increased the random coil level of CA. Glycosylation treatment of CA-CP and CA-AG exhibited lower surface hydrophobicity and higher absolute ζ-potential values, further significantly improving the functional properties of CA (e.g., solubility, foaming property, emulsifying property, thermal stability, and antioxidant activity). Accordingly, our results indicated that it is feasible for CP or AG to improve the functional properties of CA by the Maillard reaction.

Utilization of ultrasound and glycation to improve functional properties and encapsulated efficiency of proteins in anthocyanins

The purpose of this study is to explore the optimal conditions for the preparation of bovine serum albumin (BSA)/casein (CA)-dextran (DEX) conjugates by ultrasonic pretreatment combined with glycation (U-G treatment). When BSA and CA were treated with ultrasound (40% amplitude, 10 min), the grafting degree increased 10.57% and 6.05%, respectively. Structural analysis revealed that ultrasonic pretreatment changed the secondary structure, further affected functional properties of proteins. After U-G treatment, the solubility and thermal stability of BSA and CA was significantly increased, and the foaming and emulsifying capacity of proteins were also changed. Moreover, ultrasonic pretreatment and glycation exhibited a greater impact on BSA characterized with highly helical structure. Complexes fabricated by U-G-BSA/CA and carboxymethyl cellulose (CMC) exhibited protection on anthocyanins (ACNs), delaying the thermal degradation of ACNs. In conclusion, the protein conjugates treated by ultrasonic pretreatment combined with glycation have excellent functionality and are potential carrier materials.

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.

The Structural and Functional Differences between Three Species of Fish Scale Gelatin and Pigskin Gelatin

In this paper, gelatin was extracted from the scales of Coregonus peled, Carp and Bighead carp by the acid method, and the structure and functional properties of the obtained scale gelatin and food-grade pigskin gelatin (FG) were compared. The results showed that all gelatins exhibited relatively high protein (86.81-93.61%), and low lipid (0.13-0.39%) and ash (0.37-1.99%) contents. FG had the highest gel strength, probably because of its high proline content (11.96%) and high average molecular weight distribution. Low β-antiparallel was beneficial to the stability of emulsion, which led FG to have the best emulsifying property. The high content of hydrophobic amino acids may be one of the reasons for the superior foaming property of Bighead carp scales gelatin (BCG). The gel strength of Carp scales gelatin (CG) and BCG, the ESI of Coregonus peled scales gelatin (CPG) and the foaming property of BCG indicate that fish gelatin has the potential to be used in food industry as a substitute for pig skin gelatin.

Strategy and Mechanism of Rice Bran Protein Emulsion Stability Based on Rancidity-Induced Protein Oxidation: An Ultrasonic Case Study

To provide a strategy for improving the stability of rice bran protein emulsion (RBPE), rice bran proteins (RBPs) with different oxidation extents were prepared from fresh rice bran (RB) stored for different times (0, 1, 3, 5, 10 d), and RBPE was prepared with ultrasonic treatment. The ultrasonic conditions were optimized according to the results of the RBPE’s stability (when RB stored for 0, 1, 3, 5, 10 d, the optimal ultrasonic treatment conditions of RBPE were 500 w and 50 min, 400 w and 30 min, 400 w and 30 min, 300 w and 20 min, 500 w and 50 min, respectively). Additionally, the structural characteristics and the flexibility of RBPE interface protein were characterized, and the results showed that compared with native protein and excessive oxidized protein, the unfolded structure content and flexibility of interface protein of RBPE prepared by moderate oxidized protein under optimal ultrasonic intensity was higher. Furthermore, the correlation analysis showed that the RBPE stability was significantly correlated with the structural characteristics and flexibility of the RBPE interface protein (p < 0.05). In summary, ultrasonic treatment affected the interface protein’s structural characteristics and flexibility, improving the stability of RBPE prepared from oxidized RBP.

Structural Characteristics and Emulsifying Properties of Soy Protein Isolate Glycated with Galacto-Oligosaccharides under High-Pressure Homogenization

This study explored the Maillard reaction process during the glycation of soy protein isolate (SPI) with galacto-oligosaccharides (GOSs) under high-pressure homogenization (HPH) and its effects on the emulsifying properties of SPI. SPI-GOS glycation under moderate pressure (80 MPa) significantly inhibited the occurrence and extent of the Maillard reaction (p < 0.05), but homogenization pressures in the range of 80−140 MPa gradually promoted this reaction. HPH caused a decrease in the surface hydrophobicity of the glycated protein, an increase in the abundance of free sulfhydryl groups, unfolding of the protein molecular structure, and the formation of new covalent bonds (C=O, C=N). Additionally, the particle size of emulsions created with SPI-GOS conjugates was reduced under HPH, thus improving the emulsifying properties of SPI. A reduction in particle size (117 nm), enhanced zeta potential (−23 mV), and uniform droplet size were observed for the emulsion created with the SPI-GOS conjugate prepared at 120 MPa. The conformational changes in the glycated protein supported the improved emulsification function. All results were significantly different (p < 0.05). The study findings indicate that HPH provides a potential method for controlling glycation and improving the emulsifying properties of SPI.

Ultra-stable high internal phase emulsions stabilized by protein-anionic polysaccharide Maillard conjugates

This paper reports the production of O/W high internal phase emulsions (HIPEs) using protein-anionic polysaccharide Maillard conjugates. First, Maillard conjugates were prepared from soy protein isolate (SPI) or sodium caseinate (SC) proteins and Alyssum homolocarpum seed gum (AHSG) or kappa-carrageenan (kC) polysaccharides. The conjugation process was confirmed and monitored by UV spectrophotometry, Fourier transform infrared, circular dichroism, fluorescence spectroscopies, and differential scanning calorimetry. Under the optimized reaction conditions, SC-AHSG conjugates exhibited the highest glycation degree and emulsifying properties. Next, HIPEs were made using the optimized conjugates, and their microstructure, droplet size, and physical stability were evaluated. The emulsion stabilized by SC-AHSG conjugate had the lowest mean droplet size (363.07 ± 34.56 nm), orderly-packed oil droplets with monomodal distribution, the highest zeta potential (-27.70 ± 0.70 mV), high storage stability (no creaming or oil-off) and was ultra-stable against environmental stresses. Results of this research are helpful for development of emulsion-based foods with novel functionality.

Dextran Conjugation Improves the Structural and Functional Properties of Heat-Treated Protein Isolate from Cinnamomum camphora Seed Kernel

The Cinnamomum camphora seed kernel (CCSK), with high contents of medium-chain oil (~59%) and protein (~19%), is an excellent source for a plant-based food ingredient. To broaden the application of the protein isolate (PI) from CCSK in the food industry, the Maillard reaction products (MRPs) were prepared by PI and dextran (DX) under mild wet-heating conditions (60 °C, 5 h), and the structural and functional properties of the PI-DX conjugates were investigated. The covalent bond between PI and DX was confirmed by the degree of grafting and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Compared with the heated PI, the PI-DX conjugates had more ordered structure, with the decreased random coil content. The changes in tertiary structure of PI-DX conjugates were reflected by the results of intrinsic fluorescence and surface hydrophobicity. Moreover, PI-DX conjugates showed better solubility, emulsifying properties, thermal stability and antioxidant activities. These results provided a theoretical basis for the development of PI-based MRPs with desirable characteristics.

Continuous cyclic wet heating glycation to prepare myofibrillar protein-glucose conjugates: A study on the structures, solubility and emulsifying properties

Myofibrillar protein (MP) is often modified by various strategies to obtain better functional properties, which are crucial to the quality of meat products. This study prepared MP-glucose conjugates with high degrees of grafting (DG) by continuous cyclic wet heating glycation, and explored the changes in the structural and functional properties. The determination of DG, amino acid contents and Fourier transform infrared spectroscopy (FT-IR) confirmed the occurrence of glycation. The conjugates lost α-helix structures, and their intrinsic fluorescence intensity decreased while their surface hydrophobicity increased, which reflected the conformational unfolding and stretching behaviour of the molecules. Glycation resulted in a smaller particle size and lower ζ-potential, delaying molecular cross-linking during heating, thereby significantly reducing the apparent viscosity of the solutions and improving the solubility and emulsifying properties of MP. The results can provide new ideas and approaches for understanding glycation, and enrich the theoretical basis of the structure-function relationship of MP.

Improved water solubility of myofibrillar proteins by ultrasound combined with glycation: A study of myosin molecular behavior

The poor water solubility of myofibrillar proteins (MPs) limits their application in food industry, and is directly related to the molecular behavior associated with myosin assembly into filaments. This study aims to explore the effect of high-intensity ultrasound (HIU) combined with nonenzymatic glycation on the solubility, structural characteristics, and filament-forming behavior of MPs in low ionic strength media. The results showed that the HIU (200-400 W) application could promote the subsequent glycation reaction between MPs and dextran (DX) and interfere with the electrostatic balance between myosin rods, suppressing the formation of filamentous myosin polymers. Glycated MPs pretreated by 400 W HIU had the highest solubility, which corresponded to the smallest particle size, highest zeta potential, and optimum storage stability (P < 0.05). Structure analysis and microscopic morphology observations suggested that the loss of the MP superhelix and the depolymerization of filamentous polymers were the main mechanisms for MP solubilization. In conclusion, HIU combined with glycation can effectively improve the water solubility of MPs by destroying or suppressing the assembly of myosin molecules.

Preparation of modified Jiuzao glutelin isolate with carboxymethyl chitosan by ultrasound-stirring assisted Maillard reaction and its protective effect of loading resveratrol/quercetin in nano-emulsion

Jiuzao glutelin isolate (JGI) was reported to possess interface and functional properties. To enhance the stability and properties of JGI, conjugation between JGI and carboxymethyl chitosan (CTS) through ultrasound-stirring assisted Maillard reaction (UTSA-MR) was investigated and optimized. The changes of molecular distribution, secondary structure, morphology, and amino acid composition of JGI were detected after conjugation with CTS. The solubility, foaming property and stability, viscosity, and thermal stability of four conjugates (CTS-JGI, with weight ratios of 0.5:1, 1:1, 2:1, and 4:1) were significantly increased compared to native JGI. Under the optimal glycation, the conjugate (CTS/JGI, 2:1, w/w; CTS-JGI-2) exhibited the best emulsifying ability and stability against NaCl solution, in vitro antioxidant activity, and cholesterol-lowering ability. CTS-JGI-2 stabilized oil-in-water nano-emulsion improved resveratrol (RES) and quercetin (QUE) encapsulation efficiency (80.96% for RES and 93.13% for QUE) and stability during the simulated digestion process (73.23% for RES and 77.94% for QUE) due to the connection through hydrogen bonds, pi-anion, pi-sigma, and donors between CTS-JGI and RES/QUE. Taken together, the modification of JGI by conjugating with CTS through UTSA-MR could be an excellent method to improve the functional properties of JGI. CTS-JGI-2 is a potential conjugate with functions that can be used to encapsulate functional substances in the stabilized nano-emulsion.

Changes in the structural and physicochemical properties of wheat gliadin and maize amylopectin conjugates induced by dry-heating

The Maillard reaction (MR) has been known to modify proteins and optimize their physicochemical properties by conjugating with reducing sugars. The structure and physicochemical properties of wheat gliadin and maize amylopectin conjugates induced by MR were investigated under different gliadin-amylopectin ratios (2:1, 1:1, 1:2, 1:4, and 1:8). The formation of conjugates was indicated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, degree of conjugation, and browning development analyses. The Fourier transform infrared and fluorescence spectroscopy analyses suggested changes in the structures of conjugates and the microenvironment of amino acids. A remarkable decrease in the β-turn structure content and an increase in the free sulfhydryl group content were observed at a ratio of 1:8, leading to decreased allergenicity. The reaction process was commendably controlled at a ratio of 1:1 with a 59.7% degree of conjugation in this group, contributing to the amelioration of solubility and foaming properties. Meanwhile, improvements in the oil holding capacity, surface hydrophobicity, and emulsifying properties were observed at a ratio of 1:4. PRACTICAL APPLICATION: The study revealed that the conjugates produced by MR might have various degrees of improved functional properties and reduced allergenicity at different ratios of substrates. Our study might be helpful for conjugates to assist in improving the texture of products and its potential in expanding the industrial application of products with gliadin.

Improving physicochemical properties of myofibrillar proteins from wooden breast of broiler by diverse glycation strategies

The effect of diverse glycation strategies on the physicochemical and structural properties of wooden breast myofibrillar protein (WBMP) were studied. The WBMP was mixed with D-ribose (RI), sodium alginate (SA), and glucosamine (GH) respectively in a weight ratio of 1:2 (w/w) at 70 °C, and was heated for 6 h. Atomic force microscopy and particle size results showed that the glycation reaction in the presence of RI made WBMP to be more evenly dispersed in the solution and had a significantly smaller particle size (78-955 nm, average 361.06 nm) (P < 0.05). There was an increase in WBMP-RI solubility (76.23 ± 0.56%) and α-helix content (51.23 ± 1.1%) than other groups. Compared with WBMP-RI, WBMP-SA and WBMP-GH have poor performance in particle distribution, solubility and emulsification. This study clarified the aldehyde group in aldose was more suitable for the glycation modification of WBMP than the ketone group in ketose.