Effect of chitosan oligosaccharide glycosylation on the emulsifying property of lactoferrin

Impaired cellular barriers and blocked metabolic pathways contribute to inhibition of carvacrol-loaded nanoemulsions stabilized by soy protein isolate / chitooligosaccharide conjugate on S. putrefaciens

In this study, soy isolate protein / chitooligosaccharide (SPI/COS) glycosylated conjugates was prepared and employed as an emulsifier to stabilize carvacrol-loaded nanoemulsions (CNE-SPI/COS). The antibacterial properties and mechanism of CNE-SPI/COS against S. putrefaciens was investigated. The results of microbial growth curves and confocal laser scanning microscopy (CLSM) results showed that CNE-SPI/COS effectively inhibited the growth of S. putrefaciens and the killing effect of CNE-SPI/COS on S. putrefaciens was concentration-dependent. Field emission scanning electron microscopy (FESEM) images showed that CNE-SPI/COS caused folds, shrinkage, rupture and even lysis of S. putrefaciens. The results showed that CNE-SPI/COS inhibited the growth and reproduction of S. putrefaciens mainly through three targets: (i) the reduction of alkaline phosphatase (AKP) activity and protein leakage indicated that CNE-SPI/COS disrupted the integrity of cell wall and cell membrane; (ii) the reduction of intracellular protein and ATP content indicated that CNE-SPI/COS interfered the synthesis of intracellular nutrient and synthesis of energy-supplying substances; (iii) changes in the activities of succinate dehydrogenase, pyruvate kinase, and glucose 6-phosphate dehydrogenase indicated that CNE-SPI/COS impeded the normal cellular metabolic pathways such as the tricarboxylic acid cycle, the glycolytic pathway, and the pentose phosphate pathway, and the decrease in superoxide dismutase activity indicated that CNE-SPI/COS disrupted the defense system against oxidative stress. In conclusion, the encapsulation of carvacrol into the nanoemulsion system can provide theoretical support and methodological guidance for the application of nanoemulsions in microbial decontamination of aquatic products.

Structural modification of lactoferrin by epigallocatechin gallate: elucidation of its structure and exploration of its potential in promoting osteoblast proliferation

Lactoferrin (LF) and epigallocatechin gallate (EGCG) are recognized for their potent osteogenic properties. However, the osteogenic activity of LF-EGCG complexes is not fully understood. In this study, both non-covalent and covalent LF-EGCG complexes with different LF : EGCG ratios were prepared, and their effects on the LF structure and thermal stability were investigated using circular dichroism, Fourier transform infrared spectroscopy, fluorescence spectroscopy, Raman spectroscopy, and differential scanning calorimetry. The results indicated that covalent binding had a more pronounced effect on protein structure modification. The covalent complex with an LF : EGCG ratio of 5 : 1 demonstrated maximum hydrophilicity; the particle size reduced to 19.31 nm; and the denaturation temperature increased to 56.96 °C. This complex at a 100 μg mL-1 concentration significantly enhanced osteoblast proliferation, increasing the rate to 1.34-fold. The proliferation rate of osteoblasts was significantly correlated with the tyrosine residue microenvironment and hydrophobicity of the complexes. This study provides valuable insights and strategies for enhancing the nutritional efficacy of LF.

Gliadin/Konjac glucomannan particle-stabilized Pickering emulsion for honokiol encapsulation with enhanced digestion benefits

Owing to the limited availability of biocompatible, edible and natural emulsifiers, the development of Pickering emulsions applicable to the food industry still confronts challenges. Moreover, Honokiol (HNK), due to its poor stability and susceptibility to oxidation, most of the existing delivery systems are centered on injection administration routes and relatively complex in preparation, posing significant challenges for industrialization. In this research, a Pickering emulsion system stabilized by gliadin and konjac glucomannan composite particles (GKPs) was constructed using the pH cycling method and was employed for the delivery of HNK. Under the conditions of a 1:2 mass ratio of the composite particles at pH 4 and an oil phase fraction of 50 %, the storage stability of HNK was effectively enhanced, attaining a retention rate of 84.88 % ± 0.78 % at 4 °C for 14 days. In simulated in vitro digestion, this emulsion system effectively mitigated the degradation of HNK, achieving a bioavailability of 66.94 % ± 4.05 % and increasing the release of free fatty acids. Pickering emulsions stabilized by GKPs may provide a useful means of delivery of bisphenol lignans.

Carvacrol-loaded emulsions stabilized by soy protein isolate/chitosan oligosaccharide conjugates improved the quality of refrigerated sea bass (Lateolabrax maculatus)

In this study, the soybean protein isolate / chitosan oligosaccharide (SPI/COS) conjugates were developed using glycosylation and used as a stabilizer of carvacrol-loaded emulsions for refrigerating sea bass (Lateolabrax maculatus). The results of Fourier transform infrared spectroscopy and fluorescence spectroscopy showed that COS modified the secondary and tertiary structure of SPI by covalent binding. The SPI/COS conjugate with a mass ratio of SPI and COS of 4:1 (SPI/COS-4) exhibited high glycosylation degree, great water solubility and better emulsification properties. Carvacrol-loaded emulsion stabilized by the SPI/COS-4 (CE-SPI/COS-4) had nanoscale droplet size and remained stable during 40 days of storage. SPI/COS-4 aqueous solution (SPI/COS) and CE-SPI/COS-4 aqueous solution (CE-SPI/COS) in the form of immersion were applied to investigate their preservation effects on sea bass, with sterile water as control check (CK). Sea bass were stored at 4 °C and quality assessments of fish were performed periodically for up to 21 days, which included microbiological and physicochemical analysis. As suggested by microbiological analysis, CE-SPI/COS treatment could significantly inhibit the bacterial growth. The low total volatile basic nitrogen value, thiobarbituric acid value and K-value indicated that CE-SPI/COS greatly retarded protein and lipid oxidation in fish and significantly suppress the degradation of nucleotide. Moreover, fish treated with CE-SPI/COS had minimal color variation and water loss, and maintained hardness, adhesiveness, chewiness, and resilience of fish to the highest degree. Therefore, emulsions stabilized with SPI/COS conjugates may be employed as a potential strategy for the quality maintenance of sea bass.

Effects of glycosylated whey protein isolate on gelatinization, gel properties, and microstructure of wheat starch

Glycated whey protein isolate (gWPI) was produced by dry thermal reaction between whey protein isolate (WPI) and lactose, and its influence on the gelatinization, gel properties, and microstructure changes of wheat starch (WS) was systematically studied. Results showed that gWPI significantly inhibited starch gelatinization and improved starch gel properties. RVA and DSC analysis showed that gWPI decreased viscosity and gelatinization enthalpy (ΔH) in a concentration-dependent manner. When gWPI concentration was 12 %, the peak viscosity and ΔH decreased by 36 cP and 3.11 J/g, respectively. gWPI competed with WS for water and inhibited WS water absorption and expansion. Rheological results showed that the viscoelasticity of the gel decreased by adding gWPI and that of WS-gWPI was a pseudoplastic fluid with shear-thinning behavior. In addition, gWPI covered the WS surface in the form of hydrogen bonds, which inhibited the leaching of amylose, thereby reducing the particle size of the gelatinized starch and its iodine binding ability. AFM results showed that gWPI combined with WS weakened the aggregation of starch molecular chains and decreased the height of starch. In conclusion, gWPI can be used as a gelatinizing regulator to improve starch properties.

Effects of Conjugation with Basil Seed Gum on Physicochemical, Functional, Foaming, and Emulsifying Properties of Albumin, Whey Protein Isolate and Soy Protein Isolate

Protein conjugation with the Maillard reaction has received considerable attention in the past decades in terms of improving functional properties. This study evaluated the changes in the techno-functional properties of whey protein isolate (WPI), soy protein isolate (SPI), and albumin (Alb) after conjugation with basil seed gum (BSG). The conjugates were developed via the Maillard reaction. Various analyses including FT-IR, XRD, SEM, SDS-PAGE, DSC, RVA, rheology, zeta potential, emulsion, and foaming ability were used for evaluating conjugation products. Conjugation between proteins (WPI, SPI, Alb) and BSG was validated by FT-IR spectroscopy. XRD results revealed a decrease in the peak of BSG after conjugation with proteins. SDS-PAGE demonstrated the conjugation of WPI, SPI, and Alb with BSG. DSC results showed that conjugation with BSG reduced the Tg of WPI, SPI, and Alb from 210.21, 207.21, and 210.90 °C to 190.30, 192.91, and 196.66 °C, respectively. The emulsion activity and emulsion stability of protein/BSG conjugates were increased significantly. The droplet size of emulsion samples ranged from 112.1 to 239.3 nm on day 3. Nanoemulsions stabilized by Alb/BSG conjugate had the smallest droplet sizes (112.1 and 143.3 nm after 3 and 17 days, respectively). The foaming capacity of WPI (78.57%), SPI (61.91%), and Alb (71.43%) in their mixtures with BSG increased to 107.14%, 85.71%, and 85.71%, respectively, after making conjugates with BSG. The foam stability of WPI (39.34%), SPI (61.57%), and Alb (53.37%) in their mixtures with BSG (non-conjugated condition) increased to 77.86%, 77.91%, and 72.32%, respectively, after formation of conjugates with BSG. Conjugation of BSG to proteins can improve the BSG applications as a multifunctional stabilizer in pharmaceutical and food industries.

Effect of electron beam irradiation on glycosylation reaction and structural characterization of whey isolate protein

BACKGROUND

Whey protein isolate (WPI) is a high-quality animal protein resource. The modification of WPI through physical, chemical and biological methods can substantially improve the functional properties of proteins. This study investigated the effect of electron beam irradiation (EBI) on the modification of WPI-xylose glycosylation.

RESULTS

The degree of grafting and browning revealed that EBI promoted WPI glycosylation. The maximum emission wavelength of intrinsic fluorescence was red-shifted and the fluorescence intensity was reduced, suggesting that irradiation induced the unfolding of the WPI structure, thereby promoting glycosylation. Fourier-transformed infrared spectroscopy revealed that the covalent binding of the conjugates occurred on the introduction of the hydrophilic groups, resulting in decreased surface hydrophobicity. When compared with conventional wet-heat glycosylation, irradiation-assisted glycosylation improved the emulsifying activity of WPI from 179.76 ± 0.83 to 277.83 ± 1.44 m2 g-1, and the emulsifying and rheological properties improved.

CONCLUSION

These results confirmed that EBI can increase the degree of WPI glycosylation and improve the functional properties of proteins, thereby laying a theoretical foundation for the further application of WPI. © 2024 Society of Chemical Industry.

Dynamics and Stability Mechanism of Lactoferrin-EPA During Emulsification Process: Insights from Macroscopic and Molecular Perspectives

Although eicosapentaenoic acid (EPA) as a functional fatty acid has shown significant benefits for human health, its susceptibility to oxidation significantly limits its application. In this study, we developed a nanoemulsion of the lactoferrin (LTF)-EPA complex and conducted a thorough investigation of its macro- and molecular properties. By characterizing the emulsion with different LTF concentrations, we found that 1.0% LTF formed the most stable complex with EPA, which benefited the formation and stability of the emulsion against storage and freezing/thawing treatment. As the foundation block of the emulsion structure, the binding mechanism and the entire dynamic reaction process of the complex have been fully revealed through various molecular simulations and theoretical calculations. This study establishes a comprehensive picture of the LTF-EPA complex across multiple length scales, providing new insights for further applications and productions of its emulsion.

Relationship between the interfacial properties of lactoferrin-(-)-epigallocatechin-3-gallate covalent complex and the macroscopic properties of emulsions

This study explored the relationship between the interfacial behavior of lactoferrin-(-)-epigallocatechin-3-gallate covalent complex (LF-EGCG) and the stability of high internal phase Pickering emulsions (HIPPEs). The formation of covalent bond between lactoferrin and polyphenol was verified by the increase in molecular weight. In LF-EGCG group, the surface hydrophobicity, interfacial pressure, and adsorption rate were decreased, while the molecular flexibility, interfacial film viscoelasticity, and interfacial protein content were increased. Meanwhile, LF-EGCG HIPPE possessed reduced droplet size, increased ζ-potential and stability. Rheology showed the viscoelasticity, structural recovery and gel strength of LF-EGCG HIPPE were improved, giving HIPPE inks better 3D printing integrity and clarity. Moreover, the free fatty acids (FFA) release of LF-EGCG HIPPE (62.6%) was higher than that of the oil group (50.1%). Therefore, covalent treatment effectively improved the interfacial properties of protein particles and the stability of HIPPEs. The macroscopic properties of HIPPEs were positively regulated by the interfacial properties of protein particles. The result suggested that the stability of emulsions can be improved by regulating the interfacial properties of particles.

Effect of ultrasound-assisted Maillard reaction on functional properties and flavor characteristics of Oyster protein enzymatic hydrolysates

To address the delamination phenomenon during storage and flavor characteristics of Oyster protein hydrolysates (OPH). In this study, xylo-oligosaccharides (XOS) were selected to covalently graft with OPH through ultrasound-assisted Maillard reaction, and the effect of ultrasound-assisted Maillard reaction on the structure, functional properties, and flavor characteristics of OPH were investigated. The results revealed that the ultrasound treatment led to a 1.46-fold increase in the degree of grafting compared with the conventional wet-heat Maillard reaction methods. Structural analyses at various levels indicated substantial alterations in the OPH structure following the ultrasound-assisted Maillard reaction. More ordered α-helical secondary structures were shifting to random coiling, the tertiary structure showed more stretching changes, and the surface structure was characterized by loose and porous features. Compared with OPH, the solubility of the ultrasound-assisted Maillard reaction products (OPH-U-M) increased from 54.67% to 70.14%, leading to a notable enhancement in storage stability. Flavor profile analysis demonstrated a decrease in unsaturated aldehydes and ketones presenting fishy and bitter aromas, while an increase in presenting meat aroma compounds was observed in OPH-U-M. Furthermore, OPH-U-M exhibited superior antioxidant properties with DPPH and ABTS radical scavenging abilities enhancing 46.05% and 42.09% in comparison with OPH, respectively. The results demonstrated that covalently binding with XOS under ultrasonication pretreatment endowed OPH with superior functional properties (including solubility, storage stability, and antioxidant activity), and the improvement of flavor profile. This study can provide theoretical guidance and practical implications for promoting the processing applications of oyster protein.

Carvacrol-loaded nanoemulsions stabilized by soy protein isolate / chitooligosaccharide conjugates inhibited the oxidation and conformational variations of myofibrillar proteins in refrigerated sea bass (Lateolabrax maculatus)

Soy isolate protein / chitooligosaccharide (SPI/COS) glycosylated conjugates was prepared and employed as an emulsifier to stabilize carvacrol-loaded nanoemulsions (CNE-SPI/COS). The effects of CNE-SPI/COS on the oxidation and aggregation of myofibrillar protein (MPs) from sea bass (Lateolabrax maculatus) were investigated. Samples were immersed in sterile water (CK), SPI/COS solution and CNE-SPI/COS solution, respectively, follow by a 15-day refrigerated storage. MPs were extracted from fish fillets at 3-day intervals, then assessed for the oxidation degree and conformational changes in MPs, as well as structural variations in myofibrils. Compared with the CK group, the results obtained from protein oxidation assessment clarified that the oxidation and aggregation of MPs was significantly reduced by the CNE-SPI/COS treatment, as evidenced by the higher total sulfhydryl content and Ca2+-ATPase activity and lower surface hydrophobicity. Conformational analysis of MPs showed that CNE-SPI/COS was effective in maintaining the ordered secondary structure of MPs and reducing the exposure of hydrophobic residues in the hydrophobic core of the tertiary structure. In addition, CNE-SPI/COS was found to be effective in protecting the microstructure of muscle fibers and myofibrils in fish fillets. These results suggest that CNE-SPI/COS can be a promising method to prevent protein oxidation and aggregation in fish.

Glycosylated gelatin prepared based on electron beam irradiation and its physicochemical properties

The influence of electron beam irradiation (EBI) treatment on the modification of gelatin-galactose glycosylation was thoroughly examined. The results of the degree of grafting and browning revealed that EBI triggered the glycosylation reaction of gelatin. The degree of glycosylation exhibited a gradual increase with the rising irradiation dose, reaching a maximum of 25 kGy. Moreover, the irradiation process opened up gelatin's internal structure, exposing its hydrophobic groups. This exposure led to an enhancement in sample surface hydrophobicity. The fluorescence intensity at the maximum emission wavelength of the fluorescence spectra decreased; Fourier infrared spectroscopy demonstrated a new absorption peak at 1074 cm-1 for the glycosylation product. These findings substantiate that gelatin formed a new product through covalent bonding with galactose. Glycosylation boosted the emulsification stability of gelatin from 1.92 min to 10.42 min and improved its emulsification and rheological properties. These outcomes affirm that EBI can effectively induce the glycosylation reaction of gelatin, thereby enhancing its functional properties. In addition, EBI has the potential to supplant the conventional heating glycosylation method. This study lays a solid theoretical foundation for the future application of glycosylation and gelatin.

Insighting the effect of ultrasound-assisted polyphenol non-covalent binding on the functional properties of myofibrillar proteins from golden threadfin (Nemipterus virgatus)

In this study, the effect of ultrasound-assisted non-covalent binding of different polyphenols (tannins, quercetin, and resveratrol) on the structure and functional properties of myofibrillar proteins (MP) from the golden threadfin (Nemipterus virgatus) was investigated. The effect of ultrasound-assisted polyphenol incorporation on the structure and properties of MP was evaluated by multispectral analysis, interfacial properties, emulsification properties and antioxidant properties et al. The results revealed that the protein-polyphenol interaction led to a conformational change in the microenvironment around the hydrophobic amino acid residues, resulting in an increase in the equilibrium of the MP molecules in terms of affinity and hydrophobicity. Ultrasound assisted polyphenols addition also led to a significant decrease of the oil/water interfacial tension (from 21.22 mN/m of MP to 8.66 mN/m of UMP-TA sample) and a significant increase of the EAI (from 21.57 m2/g of MP to 28.79 m2/g of UMP-TA sample) and ES (from 84.76 min of MP to 124.25 min of UMP-TA). In addition, ultrasound-assisted polyphenol incorporation could enhance the antioxidant properties of MP, with the DPPH and ABTS radical scavenging rate of UMP-TA increase of 47.7 % and 55.2 % in comparison with MP, respectively. The results demonstrated that the noncovalent combination with polyphenols under ultrasound-assisted conditions endowed MP with better functional properties, including solubility, emulsification, foaming, and antioxidant properties through structure change. This study can provide innovative theoretical guidance for effectively preparing aquatic protein-polyphenol non-covalent complexes with multiple functions and improving the processing and utilization value of aquatic proteins.

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.

Conjugation of chitopentaose with β-lactoglobulin using Maillard reaction, and its effect on the allergic desensitization in vivo

The conjugation of chitopentaose (CHP) on β-lactoglobulin (βLg) via Maillard reaction was used to desensitize βLg. The stable βLg-CHP conjugate (βC-4) was formed at 4 h incubation, which contains 5 CHP attached molecules and a conjugated degree of 42 %. The conjugation promoted the thermal stability and emulsifying properties of βLg, and inhibited the immunoglobulin E (IgE) combining capacity by decreasing the content of β-sheet in βLg. Moreover, βLg-CHP conjugates were imparted with anti-oxidant properties and anti-inflammatory activities. Further, the combined action of inhibited IgE combining capacity and anti-inflammatory activities improved the allergy desensitization in βLg sensitized mice. The results showed that overexpressed IgE and inflammatory factors, unbalanced Th1-/Th2- immune cytokines were significantly attenuated after βLg was conjugated with CHP, avoiding the inflammatory lesions in spleen and colon. Additionally, the adverse changes in gut microbiota were alleviated in βC-4 group with a decrease of Bacteroidetes and increase of Firmicutes at phylum level and the probiotic bacteria of Lactobacillaceae was significantly improved at the family level. Thus, the conjugation of CHP can desensitize allergic reaction caused by βLg.

Glycation-induced enhancement of yeast cell protein for improved stability and curcumin delivery in Pickering high internal phase emulsions

Pickering high internal phase emulsions (HIPEs) have gained significant attention for various applications within the food industry. Yeast cell protein (YCP), derived from spent brewer's yeast, stands out as a preferred stabilizing agent due to its cost-effectiveness, abundance, and safety profile. However, challenges persist in utilizing YCP, notably its instability under high salt concentration, thermal processing, and proximity to its isoelectric point. This study aimed to enhance YCP's emulsifying properties through glycation with glucose and evaluate its efficacy as a stabilizer for curcumin (CUR)-loaded HIPEs. The results revealed that glycation increased YCP's surface hydrophobicity, exposing hydrophobic groups. This augmentation, along with steric hindrance from grafted glucose molecules, improved emulsifying properties, resulting in a thicker interfacial layer around oil droplets. This fortified interfacial layer, in synergy with steric hindrance, bolstered resistance to pH changes, salt ions, and thermal degradation. Moreover, HIPEs stabilized with glycated YCP exhibited reduced oxidation rates and improved CUR protection. In vitro digestion studies demonstrated enhanced CUR bioaccessibility, attributed to a faster release of fatty acids. This study underscores the efficacy of glycation as a strategic approach to augment the applicability of biomass proteins, exemplified by glycated YCP, in formulating stable and functional HIPEs for diverse food applications.

Investigation of structural and physicochemical properties of microcapsules obtained from protein-polysaccharide conjugate via the Maillard reaction containing Satureja khuzestanica essential oil

In this study, some common proteins including, whey protein isolate (WPI), soy protein isolate (SPI), and gelatin (G) conjugated with maltodextrin (MD) via Maillard reaction and were then used to encapsulate Satureja khuzestanica essential oil (SKEO). The higher glycation degree was obtained at a pH of 9 and 3 h of heating at 60 °C for SPI and WPI, and 90 °C for G. The results of FTIR and intrinsic fluorescence test showed the possibility of covalent binding formation between proteins and maltodextrin. The encapsulation efficiencies were obtained about 83.84 %, 88.95 %, and 89.27 % for MD-SPI, MD-G, and MD-WPI, respectively. Moreover, the Maillard reaction-based microcapsules had higher antioxidant activity than the physical mixture of protein-polysaccharide. The addition of SKEO to microcapsules improved antimicrobial activity. The results of this study demonstrated that MD-WPI and MD-G, as encapsulating materials, can be used to enhance the physiochemical properties of microcapsules loaded with SKEO.

Low molecular weight chitosan oligosaccharides form stable complexes with human lactoferrin

Proteins in tears, including human lactoferrin (HLF), can be deposited and denatured on contact lenses, increasing the risk of microbial cell attachment to the lens and ocular complications. The surfactants currently used in commercial contact lens care solutions have low clearance ability for tear proteins. Chitosan oligosaccharide (COS) binds to a variety of proteins and has potential for use in protein removal, especially in contact lens care solutions. Here, we analyzed the interaction mechanism of COSs hydrolyzed from chitosan from different resources with HLF. The molecular weights (MWs) and concentrations of COSs were key factors for the formation of COS-HLF complexes. Lower MWs of COSs could form more stable COS-HLF complexes. COS from Aspergillus ochraceus had a superior effect on HLF compared with COS from shrimp and crab shell with the same MWs. In conclusion, COSs could bind to and cause a conformational change in HLF. Therefore, COSs, especially those with low MWs, have potential as deproteinizing agents in contact lens care solution.

Modulation of physicochemical properties of lipid droplets using soy protein isolate and lactoferrin interfacial coatings

In order to improve the physicochemical stability of soy protein isolate (SPI) emulsion, lactoferrin (LF) was used to modify the interface layer. The stable multilayer emulsion can be formed when the content of lactoferrin is 0.5% at pH 5. The emulsion with good stability was at pH 3-7, and it was also stable to temperature change. The FFAs release of SPI emulsion and LF-SPI emulsion was 103.9% and 103.7%, respectively. The results showed that the lactoferrin layer did not hinder the digestion of oil and the bioaccessibility of carotenoids, but lactoferrin layer improved the physicochemical stability of SPI emulsions. This work provides information valuable in the design of emulsion formulations for applications in the food, pharmaceutical, and personal care industries.

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.

Insights into the Mechanism Underlying the Influence of Glycation with Different Saccharides and Temperatures on the IgG/IgE Binding Ability, Immunodetection, In Vitro Digestibility of Shrimp (Litopenaeus vannamei) Tropomyosin

Tropomyosin (TM) is a heat-stable protein that plays a crucial role as a major pan-allergen in crustacean shellfish. Despite the high thermal stability of the TM structure, its IgG/IgE binding ability, immunodetection, and in vitro digestibility can be negatively influenced by glycation during food processing, and the underlying mechanism remains unclear. In this study, TM was subjected to glycosylation using various sugars and temperatures. The resulting effects on IgG/IgE-binding capacity, immunodetection, and in vitro digestibility were analyzed, meanwhile, the structural alterations and modifications using spectroscopic and LC-MS/MS analysis were determined. Obtained results suggested that the IgG/IgE binding capacity of glycosylated TM, immunodetection recovery, and in vitro digestibility were significantly reduced depending on the degree of glycosylation, with the greatest reduction occurring in Rib-TM. These changes may be attributable to structural alterations and modifications that occur during glycosylation processing, which could mask or shield antigenic epitopes of TM (E3: 61-81, E5b: 142-162, and E5c: 157-183), subsequently reducing the immunodetection recognition and digestive enzyme degradation. Overall, these findings shed light on the detrimental impact of glycation on TMs potential allergenicity and digestibility immunodetection and provide insights into the structural changes and modifications induced by thermal processing.

Advances in preparation and application of food-grade emulsion gels

Emulsion gel is a semi-solid or solid material with a three-dimensional net structure produced from emulsion through physical, enzymatic, chemical methods or their combination. Emulsion gels are widely used in food, pharmaceutical and cosmetic industries as carriers of bioactive substances and fat substitutes due to their unique properties. The modification of raw materials, and the application of different processing methods and associated process parameters profoundly affect the ease or difficult of gel formation, microstructure, hardness of the resulting emulsion gels. This paper reviews the important research undertaken in the last decade focusing on classification of emulsion gels, their preparation methods, the influence of processing method and associated process parameters on structure-function of emulsion gels. It also highlights current status of emulsion gels in food, pharmaceutical and medical industries and provides future outlook on research directions requiring to provide theoretical support for innovative applications of emulsion gels, particularly in food industry.

A critical review of RG-I pectin: sources, extraction methods, structure, and applications

In recent years, RG-I pectin isolated by low-temperature alkaline extraction methods has attracted the attention of a large number of researchers due to its huge health benefits. However, studies on other applications of RG-I pectin are still lacking. In this study, we summarized the sources (e.g. potato pulp, sugar beet pulp, okra, apple pomace, citrus peel, pumpkin, grapefruit, ginseng, etc.), extraction methods, fine structure and applications of RG-I pectin in physiological activities (e.g. anti-cancer, anti-inflammatory, anti-obesity, anti-oxidation, immune regulation, prebiotics, etc.), emulsions, gels, etc. These neutral sugar side chains not only endow RG-I pectin with various physiological activities but the entanglement and cross-linking of these side chains also endow RG-I pectin with excellent emulsifying and gelling properties. We believe that this review can not only provide a comprehensive reading for new workers interested in RG-I pectin, but also provide a valuable reference for future research directions of RG-I pectin.

Effects of glycation with chitooligosaccharide on digestion and fermentation processes of lactoferrin in vitro

This study aimed to investigate the digestion and fermentation processes of lactoferrin (LF) glycated with chitooligosaccharide (COS) under a controlled Maillard reaction, utilizing the in vitro digestion and fermentation model, and to compare the results of these processes to LF undertaken without glycation. After gastrointestinal digestion, the products of the LF-COS conjugate were found to have more fragments with lower molecular weight than LF, and the antioxidant capabilities (via ABTS and ORAC assay) of the LF-COS conjugate digesta also increased. In addition, the undigested fractions could be further fermented by the intestinal microbiota. Compared with LF, more short-chain fatty acids (SCFAs) were generated (from 2397.40 to 2623.10 μg/g), and more species of microbiota (from 451.78 to 568.10) were observed in LF-COS conjugate treatment. Furthermore, the relative abundance of Bacteroides and Faecalibacterium that could utilize carbohydrates and metabolic intermediates to produce SCFAs also increased in LF-COS conjugate than that of LF. Our results demonstrated that glycation with COS under the controlled wet-heat treatment Maillard reaction could modify the digestion of LF and have a potentially positive influence on the intestinal microbiota community.

High-temperature glycosylation modifies the molecular structure of ovalbumin to improve the freeze-thaw stability of its high internal phase emulsion

In this study, ovalbumins (OVAs) were glycosylated with fructo-oligosaccharide (FO) at different temperatures (80 °C, 100 °C, 120 °C, and 140 °C) and durations (1 h and 2 h) via wet-heating. The glycosylated OVAs (GOVAs) were characterized by the degree of glycosylation (DG), particle size, zeta potentials, and structural changes. GOVAs-stabilized high-internal-phase emulsions (HIPEs) were then prepared to compare their macro- and microstructure and freeze-thaw stability. The results showed that the DG of GOVAs increased with the increase in glycosylation temperature and the protein structure unfolded with it. Glycosylation decreased the particle size, zeta potential, and α-helical structures and increased the β-sheets and surface hydrophobicity (H₀) of GOVAs compared with unmodified OVAs. Moreover, GOVAs-stabilized HIPEs exhibited smaller particle sizes, zeta potentials, agglomeration indexes, oil loss rates, and freezing points and higher viscoelasticity, centrifugal stabilities, flocculation indexes, and freeze-thaw stabilities. Notably, HIPEs prepared by GOVAs (glycosylated higher than 120 °C) showed the least changes in macro- and microscopic appearances after freeze-thawing. These findings will provide a novel method for improving and broadening the functionalities of OVAs and potentially develop HIPEs with enhanced freeze-thaw stabilities.

Antioxidant Activity and Cell Protection of Glycosylated Products in Different Reducing Sugar Duck Liver Protein Systems

Duck liver is an important by-product of duck food. In this study, we investigated the effects of glucose, fructose, and xylose on the antioxidant properties of glycosylated products of duck liver protein and their protective effects on HepG2 cells. The results show that the glycosylation products of the three duck liver proteins (DLP-G, DLP-F, and DLP-X) all exhibit strong antioxidant activity; among three groups, DLP-X shows the strongest ability to scavenge DPPH, ·OH free radicals, and ABTS⁺ free radicals. The glycosylated products of duck liver protein are not toxic to HepG2 cells and significantly increase the activity of antioxidant enzymes such as SOD, CAT, and GSH-Px in HepG2 cells at the concentration of 2.0 g/L, reducing oxidative stress damage of cells (p < 0.05). DLP-X has a better effect in reducing oxidative damage and increasing cellular activity in HepG2 cells than DLP-G and DLP-F (p < 0.05). In this study, the duck liver protein glycosylated products by glucose, fructose, and xylose were named as DLP-G, DLP-F, and DLP-X, respectively.

Glycosylation with bioactive polysaccharide obtained from Rosa roxburghii Tratt fruit to enhance the oxidative stability of whey protein isolate emulsion

Whey protein isolate (WPI) is an excellent source of emulsifier, but its function is limited for oxidative unstable in emulsion. In this study, WPI was glycated with Rosa roxburghii Tratt fruit polysaccharides (RTFP) by Maillard reaction under optimum conditions. The sodium dodecyl sulfate-polyacrylamide gel electrophoresis profile confirmed the formation of WPI-RTFP conjugates. The intrinsic fluorescence spectrum, CD and FT-IR indicated that the structure of WPI was affected after glycated with RTFP. In addition, the antioxidant activity of WPI-RTFP conjugates and WPI-RTFP emulsion were 3.5-fold and 1.5-fold stronger than that of WPI and WPI emulsion, respectively. Furthermore, the emulsion coated by conjugates demonstrated better oxidative stability than WPI with less peroxides produced after accelerated oxidation for 7 days. The results lay good foundation for the modification of protein by natural bioactive polysaccharides as well as for the application in healthy foods.