Structure and physiochemical characteristics of whey protein isolate conjugated with xylose through Maillard reaction at different degrees

Mechanistic insights into the changes of biological activity and physicochemical characteristics in Lacticaseibacillus paracasei fortified milk powder during storage

To clarify the change mechanism of biological activity and physicochemical characteristics in Lacticaseibacillus paracasei JY025 fortified milk powder (LFMP) during storage, morphological observation, JY025 survival, storage stability, and metabolomics of LFMP were determined during the storage period in this study. The results showed that the LFMP had a higher survival rate of JY025 compared with the bacterial powder of JY025 (LBP) during storage, which suggested that milk powder matrix could reduce strain JY025 mortality under prolonged storage in the LFMP samples. The fortification of strain JY025 also affected the stability of milk powder during the storage period. There was lower water activity and higher glass transition temperature in LFMP samples compared with blank control milk powder (BCMP) during storage. Moreover, the metabolomics results of LFMP indicated that vitamin degradation, Maillard reaction, lipid oxidation, tricarboxylic acid cycle, and lactobacilli metabolism are interrelated and influence each other to create complicated metabolism networks.

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

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

Structural and sensory characteristics of ultrasonic assisted wet-heating Maillard reaction products of Giant salamander protein hydrolysates

BACKGROUND

Chinese giant salamander protein hydrolysates (CGSPH) are beneficial to human health as a result of their high content of amino acids and peptides. However, the formation of bitter peptides in protein hydrolysates (PHs) would hinder their application in food industry. The ultrasound assisted wet-heating Maillard reaction (MR) is an effective way to improve the flavor of PHs. Thus, the effect of ultrasonic assisted wet-heating MR on the structure and flavor of CGSPH was investigated in the present study.

RESULTS

The results indicated that the ultrasound assisted wet-heating MR products (MRPs) exhibited a higher degree of graft and more significant changes in the secondary and tertiary structures of CGSPH compared to traditional wet-heating MRPs. Moreover, ultrasound assisted wet-heating MR could significantly increase the content of small molecule peptides and reduce the content of free amino acids of CGSPH, which resulted in more significant changes in flavor characteristics. The changed in flavor properties after MR (especially ultrasound assisted wet-heating MRPs) were mainly manifested by a significant reduction in bitterness, as well as a significant increase in the content of aromatic aldehyde ester compounds such as furan-2-carbaldehyde, butanal, benzaldehyde, furfural, etc. CONCLUSIONS: Ultrasound assisted wet-heating MR between CGSPH and xylose could be a promising way to improve the sensory characteristics of CGSPH. © 2024 Society of Chemical Industry.

The non-covalent and covalent interactions of whey proteins and saccharides: influencing factor and utilization in food

During the application of Whey proteins (WPs), they often have complex interactions with saccharides (Ss), another important biopolymer in food substrate. The texture and sensory qualities of foods containing WPs and Ss are largely influenced by the interactions of WPs-Ss. Moreover, the combination of WPs and Ss is possible to produce many excellent functional properties including emulsifying properties and thermal stability. However, the interactions between WPs-Ss are complex and susceptible to some processing conditions. In addition, with different interaction ways, they can be applied in different fields. Therefore, the non-covalent interaction mechanisms between WPs-Ss are firstly summarized in detail, including electrostatic interaction, hydrogen bond, hydrophobic interaction, van der Waals force. Furthermore, the existence modes of WPs-Ss are introduced, including complex coacervates, soluble complexes, segregation, and co-solubility. The covalent interactions of WPs-Ss in food applications are often formed by Maillard reaction (dry or wet heat reaction) and occasionally through enzyme induction. Then, two common influencing factors, pH and temperature, on non-covalent/covalent bonds are introduced. Finally, the applications of WPs-Ss complexes and conjugations in improving WP stability, delivery system, and emulsification are described. This review can improve our understanding of the interactions between WPs-Ss and further promote their wider application.

Antioxidant and antibrowning properties of Maillard reaction products in food and biological systems

Oxidative damage refers to the harm caused to biological systems by reactive oxygen species such as free radicals. This damage can contribute to a range of diseases and aging processes in organisms. Moreover, oxidative deterioration of lipids is a serious problem because it reduces the shelf life of food products, degrades their nutritional value, and produces reaction products that could be toxic. Antioxidants are effective compounds for preventing lipid oxidation, and synthetic antioxidants are frequently added to foods due to their high effectiveness and low cost. However, the safety of these antioxidants is a subject that is being discussed in the public more and more. Synthetic antioxidants have been found to have potential negative effects on health due to their ability to accumulate in tissues and disrupt natural antioxidant systems. During thermal processing and storage, foods containing reducing sugars and amino compounds frequently produce Maillard reaction products (MRPs). Through the chelation of metal ions, scavenging of reactive oxygen species, destruction of hydrogen peroxide, and suppression of radical chain reaction, MRPs exhibit excellent antioxidant properties in a variety of food products and biological systems. Also, the capacity of MRPs to chelate metals makes them as a potential inhibitor of the enzymatic browning in fruits and vegetables. In this book chapter, the methods used for the evaluation of antioxidant activity of MRPs are provided. Moreover, the antioxidant and antibrowning activities of MRPs in food and biological systems is discussed. MRPs can generally be isolated and used as commercial preparations of natural antioxidants.

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

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

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.

Assessing the effect of Maillard reaction products on the functionality and antioxidant properties of Amaranth-red seaweed blends

Plant-based proteins, represented by amaranth in our study, embrace a potential as an ingredient for the functional-food formulation. However, their efficacy is hindered by inherent limitations in solubility, emulsification, and antioxidant traits. The Maillard reaction, a complex chemical-process resulting in a diverse array of products, including Maillard conjugates and Maillard reaction products (MRPs), can employ variable effects on these specific attributes. To elucidate the influence of this reaction and the MRPs on the aforementioned properties, we used a complex blend of dehydrated seaweed Gracilaria and amaranth protein to create a conjugate-MRP blend. Our investigations revealed that the resultant incorporation enhanced solubility, emulsification, and antioxidant properties, while the intermediates formed did not progress to advanced glycation stages. This change is likely attributed to the dual effect of conjugates that altered the secondary protein structure, while the generation and/or preservation of MRPs post ultrasonication and spray drying enhanced its antioxidant potential.

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

Recently, increasing studies have shown that the functional properties of proteins, including emulsifying properties, antioxidant properties, solubility, and thermal stability, can be improved through glycation reaction under controlled reaction conditions. The use of glycated proteins to stabilize hydrophobic active substances and to explore the gastrointestinal fate of the stabilized hydrophobic substances has also become the hot spot. Therefore, in this review, the effects of glycation on the structure and function of food proteins and the physical stability and oxidative stability of protein-stabilized oil/water emulsions were comprehensively summarized and discussed. Also, this review sheds lights on the in vitro digestion characteristics and edible safety of emulsion stabilized by glycated protein. It can further serve as a research basis for understanding the role of structural features in the emulsification and stabilization of glycated proteins, as well as their utilization as emulsifiers in the food industry.

Structure, chemical stability and antioxidant activity of melanoidins extracted from dark beer by acetone precipitation and macroporous resin adsorption

Melanoidins contribute to the sensory and functional properties of dark beers. The structure, stability, and antioxidant activity of acetone precipitation extracted melanoidins (APE-M) and macroporous resin adsorption extracted melanoidins (MAE-M) from dark beer were investigated. The structural properties of melanoidins were characterized using Fourier transform infrared spectroscopy (FTIR), circular dichroism (CD), scanning electron microscopy (SEM), and the solution storage stability, thermal behavior and antioxidant activity of melanoidins in dark beers were evaluated. MAE-M revealed more sophisticated structures than APE-M, including more concrete characteristics of Maillard reaction (MR) products in FTIR (1550-1500 cm^-1), more ordered secondary structure in CD spectra, and thinner slices as well as more microspheres in SEM. The solution storage stability assay showed that certain factors, including 55 °C, 5 % v/v ethanol, UV light, and H₂O₂ solution, accelerated the degradation of melanoidins. The moderate extraction process of MAE-M performed a minor enthalpy change (-92.28 Jg^-1) in the DSC-TG test than that of APE-M (-319.41 Jg^-1). Furthermore, the ABTS and DPPH radical scavenging activities and the FRAP assay demonstrated that the antioxidant activity of MAE-M was almost twice that of APE-M. In general, MAE was more effective in extracting beer melanoidins while maintaining its accurate structure and profitable antioxidant activity than APE.

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.

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.

Effect of carbon numbers and structures of monosaccharides on the glycosylation and emulsion stabilization ability of gelatin

Herein, the effect of saccharide glycosylation by nine monosaccharides on bovine bone gelatin for the stabilization of fish oil-loaded emulsions was explored. The gelatin modification was analyzed and then the emulsifying properties of monosaccharide-modified gelatins were analyzed at pH 9.0 and 3.0. The results demonstrated that glycosylated gelatin structure, droplet stability, creaming stability, and liquid-gel transition time were dependent on monosaccharide carbon numbers, monosaccharide structures, and solution pH. Glycosylation modification of gelatins did not obviously change the emulsion droplet stability at pH 9.0, whereas it increased the emulsion droplet stability at pH 3.0. Glycosylation modification of gelatins did not obviously change the emulsion creaming index values (5.1%-8.4% at pH 9.0 and 25.8%-33.1% at pH 3.0). Three-carbon and four-carbon monosaccharides glycosylation significantly increased emulsion liquid-gel transition times. This work provided useful information to understand the effects of carbon numbers and structures of monosaccharides on the protein modification.

Whey Protein Isolate-Xylose Maillard-Based Conjugates with Tailored Microencapsulation Capacity of Flavonoids from Yellow Onions Skins

The objective of this study is to encapsulate flavonoids from yellow onion skins in whey protein isolates (WPI) and xylose (X), by Maillard-based conjugates, as an approach to improve the ability to entrap flavonoids and to develop powders with enhanced antioxidant activity. WPI (0.6%, w/v) was conjugated to X (0.3%, w/v) through the Maillard reaction at 90 °C for 120 min, in the presence of a flavonoid-enriched extract. Two variants of powders were obtained by freeze-drying. The glycation of WPI allowed a better encapsulation efficiency, up to 90.53 ± 0.29%, corresponding to a grafting degree of 30.38 ± 1.55%. The molecular modelling approach was used to assess the impact of X interactions with α-lactalbumin and β-lactoglobulin on the ability of these proteins to bind the main flavonoids from the yellow onion skins. The results showed that X might compete with quercetin glucosides to bind with α-lactalbumin. No interference was found in the case of β-lactoglobulin. The microstructural appearance of the powders revealed finer spherosomes in powder with WPI-X conjugates via the Maillard reaction. The powders were added to nachos, followed by a phytochemical characterization, in order to test their potential added value. An increase in antioxidant activity was observed, with no significant changes during storage.