Model Reaction Systems Research Articles

Multi‐response kinetic study of Maillard reaction hazards in the glucose‐lysine model system

AbstractBACKGROUNDNε‐carboxymethyllysine (CML), Nε‐carboxyethyllysine (CEL) and α‐aminoadipic acid (AAA) are important foodborne hazards and their intake can cause a variety of diseases in humans. It is extremely important to investigate the formation mechanism of CML, CEL and AAA, as well as their association with each other when aiming to control their production.RESULTSA multi‐response kinetic model was developed within the glucose‐lysine Maillard reaction model system. The concentrations of glucose, lysine, glyoxal (GO), methylglyoxal (MGO), CML, CEL and AAA were quantified at different temperature (100–160 °C) and at different intervals (0–60 min). The experimental data were fitted to the proposed model to calculate kinetic parameters for the corresponding steps. The results indicated that the production of CML was primarily relied on the direct oxidative cleavage of the Amadori product, rather than the reaction between GO and Lys, whereas CEL and AAA were generated through the reaction of MGO with Lys. Significantly, the reaction between α‐dicarbonyl compounds and Lys preferentially generated CML and CEL, resulting in the lower concentrations of AAA compared to CML and CEL.CONCLUSIONThe multi‐response kinetic model developed in the present study can be applied well to the Maillard reaction. The relationship between the formation mechanisms of CML, CEL and AAA is also explained. © 2024 Society of Chemical Industry.

Intramolecular charge transfer dynamics of anthraquinone derivatives in the confined environments of reverse micelles

Reverse micelles (RMs) are considered important model systems for molecular dynamics and chemical reactions, where the nanopools of aqueous and nonaqueous polar cores are separated from the surrounding organic phase via a monolayer of surfactant molecules. Here, we report the intramolecular charge transfer (ICT) dynamics of anthraquinone derivatives in the methanol-in-oil RMs composed of nonionic surfactants Igepal by femtosecond transient absorption and fluorescence upconversion spectroscopy. The ICT dynamics slow down inside the RMs due to abnormally diminished solvent motions and restricted internal rotations of the (methyl)amino group during the ICT in the excited states. The micelle size-dependent dynamics of anthraquinone derivatives inside the RMs were compared with the results in bulk aliphatic alcohols and understood as the changes in the microenvironment properties such as microviscosity.

The interaction between lipid oxidation and the Maillard reaction model of lysine-glucose on aroma formation in fragrant sesame oil

The formation mechanism behind the sophisticated aromas of sesame oil (SO) has not been elucidated. The interaction effects of the Maillard reaction (MR) and lipid oxidation on the aroma formation of fragrant sesame oil were investigated in model reaction systems made of l-lysine (Lys) and d-glucose (Glc) with or without fresh SO (FSO) or oxidized SO (OSO). The addition of OSO to the Lys-Glc model increased the MR browning at 294 nm and 420 nm and enhanced the DPPH radical scavenging activity greater than the addition of FSO (p < 0.05). The presence of lysine and glucose inhibited the oxidation of sesame oil, reduced the loss of γ-tocopherol, and facilitated the formation of sesamol (p < 0.05). The Maillard-lipid interaction led to the increased concentrations of some of the alkylpyrazines, alkylfurans, and MR-derived ketones and acids (p < 0.05) while reducing the concentrations of other pyrazines, lipid-derived furans, aliphatic aldehydes, ketones, alcohols, and acids (p < 0.05). The addition of FSO to the MR model enhanced the characteristic roasted, nutty, sweet, and fatty aromas in sesame oil (p < 0.05), while excessive lipid oxidation (OSO) brought about an unpleasant oxidized odor and reduced the characteristic aromas. This study helps to understand the sophisticated aroma formation mechanism in sesame oil and provides scientific instruction for precise flavor control in the production of sesame oil.

The relevance of the initial conditions in glassy carbon electrode sensing applications: the ferri/ferrocyanide redox reaction model system in aqueous solution

Carbon electrodes, especially the glassy carbon electrodes (GCE) are widely accepted as very versatile sensing platforms. However, correlating the behaviour of the ferri/ferrocyanide redox couple ([Fe(CN)6]3-/4−) with the GCE's surface modification is challenging. The surface modification can be achieved by applying a pre-conditioning electrochemical activation procedure. Hence, we report the investigation performed in order to provide further insights into the electrochemical behaviour of the commonly used redox probe in aqueous solutions. To that aim we took advantage of powerful and complementary electrochemical analytical techniques, like cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Thus, this work highlights the critical role of the GCE initial conditions for optimizing the charge transfer processes and therefore to improve the [Fe(CN)6]3-/4− performance in sensing applications. The best results were obtained in phosphate buffer saline solution with previous electrochemical activation by fast potential cycling between [-0.5 and +1.8] V (vs. Ag|AgCl (KCl sat.)). Finally, one can consider this an eco-friendly and simple procedure to be carried out in the lab, however, its use must be carefully optimized when exploring other systems, as highlighted herein.

Regulated Formation of Inhibited Color and Enhanced Flavor Derived from Heated 2-Threityl-Thiazolidine-4-Carboxylic Acid with Additional Cysteine Targeting at Different Degradation Stages.

This study explored the addition of cysteine (Cys) affecting the color formation of heated 2-threityl-thiazolidine-4-carboxylic acid (TTCA) models under different reaction conditions and pointed out that temperature was considered to be the key parameter influencing the color inhibition behavior of Cys on TTCA reaction models. Results revealed that additional Cys not only controlled the reaction progress and blocked the formation pathway of browning but also changed the formation rate, intensity, and profile of the flavor generated from the TTCA reaction model. Meanwhile, the mechanism of Cys simultaneously regulating the formation of color and flavor was revealed through monitoring of the characteristic downstream products during TTCA degradation and model reaction systems. At the initial stage, the additional Cys acted as a color inhibitor before the deoxyxylosone degradation, preventing the formation of downstream browning precursors. With the continuous depletion of Cys as well as the generation of furans or α-dicarbonyl compounds, Cys became a flavor enhancer to act on the browning precursors and to provide more sulfur/nitrogen elements for the TTCA thermal reaction system. Therefore, Cys had the potential to act as both color inhibitor and flavor fortifier to match with TTCA for the preparation of a light-colored flavoring base with a desired flavor during thermal processing.

Effect of solvent viscosity on the activation barrier of hydrogen tunneling in the lipoxygenase reaction

Hydrogen tunneling in enzyme reactions has played an important role in linking protein thermal motions to the chemical steps of catalysis. Lipoxygenases (LOXs) have served as model systems for such reactions, showcasing deep hydrogen tunneling mechanisms associated with enzymatic C–H bond cleavage from polyunsaturated fatty acids. Here, we examined the effect of solvent viscosity on the protein thermal motions associated with LOX catalysis using trehalose and glucose as viscogens. Kinetic analysis of the reaction of the paradigm plant orthologue, soybean lipoxygenase (SLO), with linoleic acid revealed no effect on the first-order rate constants, kcat, or activation energy, Ea. Further studies of SLO active site mutants displaying varying Eas, which have been used to probe catalytically relevant motions, likewise provided no evidence for viscogen-dependent motions. Kinetic analyses were extended to a representative fungal LOX from M. oryzae, MoLOX, and a human LOX, 15-LOX-2. While MoLOX behaved similarly to SLO, we show that viscogens inhibit 15-LOX-2 activity. The latter implicates viscogen sensitive, conformational motions in animal LOX reactions. The data provide insight into the role of water hydration layers in facilitating hydrogen (quantum) tunneling in LOX.

Antioxidant activities and emulsification properties of the new model systems of whey proteins and reduced sugars

The final products formed from the various systems of the Maillard reactions possess different functional properties such as browning intensity, antioxidant activity, and emulsion stability. To study these properties and activities, different systems of whey proteins reaction with glucose and fructose at different concentrations to form a new model system of Maillard reaction products (MRPs) was observed. Results showed that high optical densities (peaks) at 280 and 420 nm indicated the formation of the intermediate stages of MRPs and the formation of advanced MRPs, respectively. Additionally, results showed that these Maillard reaction model systems possessed different antioxidant activities as demonstrated by DPPH and reducing power assays (20 - 93.2% and 40 - 90%, respectively) depending on the type and concentration of sugar, and the incubation time. The whey protein-fructose model system possessed high antioxidant activity (93.2%), and had the highest percentage on the emulsion stability index (75.4%). The whey protein-fructose model systems comprised the highest number of the studied model systems to form MRPs, and had highly powerful antioxidant activity and emulsifying index.

Determinants of continuous intention to use retail apps: A hybrid PLS-ANN approach

ABSTRACT Although consumers’ intent to use retail applications (apps) over time is crucial to their success, academics have paid less attention to this factor. Using the attractiveness of alternatives as a moderator, this study aims to determine how users’ perceptions of app quality affect their propensity to use the app in the future through measures of performance confirmation and trust. The study analyzed the 435 acceptable responses using a hybrid approach incorporating partial least squares structural equation modeling and deep learning (artificial neural network). Results showed that utilitarian and hedonic performance confirmation and trust drive the use of retail apps. Service and information qualities validate trust and utilitarian and hedonic performance confirmation. System quality solely influences utilitarian performance confirmation. The attractiveness of alternatives adversely moderates utilitarian performance confirmation and continuation intention. The novel theoretical model integrating stimulus–organism–reaction model and information system success model reveals the relative importance of specific aspects, providing a better understanding of retail app users’ continuation intention.

Comprehensive Study of the Mechanism of the “Aromatic Nitroso Oxide–Olefin” Interaction as a Function of the Reagents’ Structure

Using reaction model systems (nitroso oxide ArNOO, Ar = Me2NC6H4 or O2NC6H4; exhaustive set of methyl- and cyano-substituted ethylenes), a detailed study of the reaction mechanism of ArNOO with unsaturated compounds was carried out using the density functional theory (M06L/6311 + G(d,p)). The reaction is preceded by the formation of a reagent complex of stacking type, which is favorable for further transformation. Depending on the structure of alkene, the reaction may proceed via two extreme mechanisms: synchronous (3 + 2)-cycloaddition (the most typical case) or one-center nucleophilic attack of the terminal oxygen atom of ArNOO on the less substituted carbon atom of the double bond. The last direction becomes dominant only under special reaction conditions: ArNOO with a strong electron-donating substituent in the aromatic ring, an unsaturated compound with a significantly depleted electron density on C═C bonds, and a polar solvent. In other cases, a different degree of asynchrony in the (3 + 2)-cycloaddition is possible; however, the main intermediate preceding stable reaction products is 4,5-substituted 3-aryl-1,2,3 dioxazolidine in any event. Both thermodynamic and kinetic arguments suggest the most probable decomposition of dioxazolidine into a nitrone and a carbonyl compound. It has been shown for the first time that the polarization of the C═C bond is a powerful factor regulating the reactivity in the reaction under study. The results of the theoretical study show excellent agreement with known experimental data for a wide variety of reacting systems.

Solvent Dynamics of Aqueous Halides before and after Photoionization.

Electron transfer reactions can be strongly influenced by solvent dynamics. We study the photoionization of halides in water as a model system for such reactions. There are no internal nuclear degrees of freedom in the solute, allowing the dynamics of the solvent to be uniquely identified. We simulate the equilibrium solvent dynamics for Cl-, Br-, I-, and their respective neutral atoms in water, comparing quantum mechanical/molecular mechanical (QM/MM) and classical molecular dynamics (MD) methods. On the basis of the obtained configurations, we calculate the extended X-ray absorption fine structure (EXAFS) spectra rigorously based on the MD snapshots and compare them in detail with other theoretical and experimental results available in the literature. We find our EXAFS spectra based on QM/MM MD simulations in good agreement with their experimental counterparts for the ions. Classical MD simulations for the ions lead to EXAFS spectra that agree equally well with the experiment when it comes to the oscillatory period of the signal, even though they differ from the QM/MM radial distribution functions extracted from the MD. The amplitude is, however, considerably overestimated. This suggests that to judge the reliability of theoretical simulation methods or to elucidate fine details of the atomistic dynamics of the solvent based on EXAFS spectra, the amplitude as well as the oscillatory period need to be considered. If simulations fail qualitatively, as does the classical MD for the aqueous neutral halogen atoms, the resulting EXAFS will also be strongly affected in both oscillatory period and amplitude. The good reliability of QM/MM-based EXAFS simulations, together with clear qualitative differences in the EXAFS spectra found between halides and their atomic counterparts, suggests that a combined theory and experimental EXAFS approach is suitable for elucidating the nonequilibrium solvent dynamics in the photoionization of halides and possibly also for electron transfer reactions in more complex systems.

Predicting the formation of 2-amino-3-methyl-imidazole[4,5-f]quinoline (IQ) in the Maillard reaction model system under various reaction conditions

The 2-amino-3-methyl-imidazole [4,5-f] quinoline (IQ) is a compound generated during the Maillard reaction while heating protein-rich foods and has been classified as a class 2A possible human carcinogen that has attracted ongoing public concern. However, the formation mechanism of IQ remains unknown. Herein, we investigated the formation mechanism of IQ in the Maillard reaction model system under various reaction conditions (temperature, time, and pH). The results showed that various conditions significantly influenced the precursors, reactive carbonyl species, and IQ formation (P < 0.05). There was regularity between IQ and various conditions, and the R2 in the fitting curves were between 0.90 and 0.99. To further explore the relationship between IQ and various conditions, a partial least squares (PLS) prediction model was constructed. The model indicates that temperature is a significant contributor to the formation of IQ during the Maillard reaction. Further analysis indicated that crotonaldehyde plays a vital role. Crotonaldehyde could promote IQ formation at low addition levels but inhibit its formation at high addition levels. Possible effects of crotonaldehyde on the formation of IQ were proposed. Overall, this research will help to identify more effective ways to reduce the formation of IQ in meat products, which can improve their safety for human consumption.

Investigation of the Quinone-quinone and Quinone-catechol products using 13C labeling, UPLC-Q-TOF/MS and UPLC-Q-Exactive Orbitrap/MS

Quinones are highly reactive oxidants and play an essential role in inducing quality deterioration of fruit and vegetable products. Here, a novel stable isotope-labeling approach in combination with high-resolution tandem mass spectrometry UPLC-Q-TOF/MS and UPLC-Q-Exactive Orbitrap/MS, was successfully applied in tracking quinone reaction pathways in both real wines and model reaction systems. Unexpectedly, the binding products of quinone-quinone and quinone-catechol that are not derived from either nucleophilic reaction or redox reaction were discovered and showed the significant high peak area.Self-coupling reactions of semiquinone radicals might provide a possible interpretation for the formation of quinone-quinone products, and a charge transfer reaction coupled with a complementary donor–acceptor interaction is feasibly responsible for the products with a quinone-catechol structure. These findings endow a new perspective for quinone metabolic pathway in foods.

Reduced asynchronism between regenerative cysteine and fragments of deoxyosones promoting formation of sulfur-containing compounds through extra-added xylose and elevated temperature during thermal processing of 2‑threityl-thiazolidine-4-carboxylic acid

The flavor intensity of thermally processed 2‑threityl-thiazolidine-4-carboxylic acid (TTCA) was significantly improved to 1.56 times of that generated from MRPs, but its flavor profile was not as desirable as that of fresh MRPs. The synergistic effect between the additional xylose (Xyl) and elevated temperature was proposed and confirmed via the quantitative analyses of regenerative cysteine (Cys) and fragments of deoxyosones (MGO/GO), which reduced the asynchronism between the formation of released Cys from degraded TTCA and retro-aldolisation products of the intermediate deoxyosones. This synergistic effect further enhanced the Strecker degradation of Cys as well as its thermal degradation and thereby promoted the formation of characteristic flavor substances including sulfur-containing compounds and pyrazines, and the total concentrations of TTCA reaction model reached 205.954 μg/L with additional Xyl at 140 °C. Model reaction systems were employed to verify this hypothesis and the proposed mechanism was further elucidated through isotope labeling technique.

Acceleration effect of galacturonic acid on acrylamide generation: evidence in model reaction systems.

Acrylamide (AA) is a potential carcinogen formed in food rich in carbohydrate during heating. Recently, AA has been found in several fruit products, such as prune juice, sugarcane molasses and canned black olives. This study focused on the role of galacturonic acid (GalA), the main acid hydrolysis product of fruit pectin, in AA formation in three model systems - asparagine (Asn)/glucose (Glc), Asn/GalA, and Asn/Glc/GalA - during heating under different pH values (pH3.8-7.8), Glc concentration (0-0.1mol L-1 ), molar ratio of substrates (Asn/Glc=1:1, 0.025-0.5mol L-1 ) and temperature (120-180 °C) for 30 min, respectively. The results suggested that the addition of 0.1mol L-1 GalA strongly accelerated AA formation in a manner dependent on pH value and temperature (P < 0.05). AA concentration under different Glc concentration and molar ratio of substrates suggested that GalA was more reactive than Glc when reacted with Asn. Furthermore, the Amadori rearrangement product/Schiff base/oxazolidine-5-one were identified as the intermediates formed in the Asn/GalA model system using ultra-performance liquid chromatography-quadrupole-time-of-flight-mass spectrometry. The results suggested that Maillard reaction between Asn and GalA might contribute to AA formation. This study is significant in elucidating the contribution of interaction between components for AA formation in fruit products. © 2022 Society of Chemical Industry.

Distinct immune stimulatory effects of anti-human VISTA antibodies are determined by Fc-receptor interaction.

VISTA (PD-1H) is an immune regulatory molecule considered part of the next wave of immuno-oncology targets. VISTA is an immunoglobulin (Ig) superfamily cell surface molecule mainly expressed on myeloid cells, and to some extent on NK cells and T cells. In previous preclinical studies, some VISTA-targeting antibodies provided immune inhibitory signals, while other antibodies triggered immune stimulatory signals. Importantly, for therapeutic antibodies, the isotype backbone can have a strong impact on antibody function. To elucidate the mode of action of immune stimulatory anti-VISTA antibodies, we studied three different anti-human VISTA antibody clones, each on three different IgG isotypes currently used for therapeutic antibodies: unaltered IgG1 (IgG1-WT), IgG1-KO (IgG1-LL234,235AA-variant with reduced Fc-effector function), and IgG4-Pro (IgG4- S228P-variant with stabilized hinge region). Antibody functionality was analysed in mixed leukocyte reaction (MLR) of human peripheral blood mononuclear cells (PBMCs), as a model system for ongoing immune reactions, on unstimulated human PBMCs, as a model system for a resting immune system, and also on acute myeloid leukemia (AML) patient samples to evaluate anti-VISTA antibody effects on primary tumor material. The functions of three anti-human VISTA antibodies were determined by their IgG isotype backbones. An MLR of healthy donor PBMCs was effectively augmented by anti-VISTA-IgG4-Pro and anti-VISTA-IgG1-WT antibodies, as indicated by increased levels of cytokines, T cell activation markers and T cell proliferation. However, in a culture of unstimulated PBMCs of single healthy donors, only anti-VISTA-IgG1-WT antibodies increased the activation marker HLA-DR on resting myeloid cells, and chemokine levels. Interestingly, interactions with different Fc-receptors were required for these effects, namely CD64 for augmentation of MLR, and CD16 for activation of resting myeloid cells. Furthermore, anti-VISTA-IgG1-KO antibodies had nearly no impact in any model system. Similarly, in AML patient samples, anti-VISTA-antibody on IgG4-Pro backbone, but not on IgG1-KO backbone, increased interactions, as a novel readout of activity, between immune cells and CD34+ AML cancer cells. In conclusion, the immune stimulatory effects of antagonistic anti-VISTA antibodies are defined by the antibody isotype and interaction with different Fc-gamma-receptors, highlighting the importance of understanding these interactions when designing immune stimulatory antibody therapeutics for immuno-oncology applications.

Variation in spin contamination and diradical character with distance between a singlet biradical molecule and surface

As diradical molecules are used to perform various unique functions, they are expected to be applied as molecular devices. In addition, theoretical calculations based on density functional theory (DFT) are critical tools in the field of computational material science. In the DFT calculations of a diradical molecule, investigation of the spin contamination error and estimation of the diradical character, which is a feature of diradical molecules, are necessary. However, little is known regarding the variation in the spin contamination error and diradical character with the distance from a surface. These data are essential in the fields of physical chemistry and surface science to enable the study of the effects of surface interactions on strongly correlated electrons. Herein, the variations were clarified by performing approximate spin-projection DFT/plane-wave (AP-DFT/plane-wave) calculations using three reaction model systems: (1) diradical adsorption state → non-diradical molecule, (2) non-diradical adsorption state → diradical molecule, and (3) diradical adsorption state → diradical molecule. Variations in the diradical character were monotonic, whereas the spin contamination error exhibited extreme values and inflections. This was because the interaction with the surface exhibited two opposing effects: (1) the diradical character of the adsorbate increased, which increased the spin contamination error, and (2) the energy difference between the open singlet and high-spin states decreased, which decreased the spin contamination error. When a diradical/non-diradical transformed owing to surface adsorption, the effect of the spin contamination error on the adsorption energy became large. Hence, spin contamination should be analysed when the considered adsorption system features diradical/non-diradical transformations. In addition, the diradical character was affected by a surface even when dispersion forces were the major adsorption stabilisation factor. This indicated that the optimisation of the surface interactions was critical in the immobilisation of diradical molecules.

Structural characterization of polar melanoidins deriving from Maillard reaction intermediates – A model approach

Chemical conversions of reducing sugars and amino compounds induce the formation of heterogenous, high-molecular-weight colorants (‘melanoidins’) with widely unknown chemical structures. Model experiments of reactive intermediates have proven to be suitable for unravelling the formation mechanisms of colored reaction products. Here, the active methylene norfuraneol was selected and incubated individually as well as in combination with glyoxal, glycolaldehyde, and acetaldehyde at elevated temperatures. Photometric and chromatographic methods as well as mass spectrometry were used to analyze the colored reaction products and reveal the reactivity of different carbonyls regarding the formation of heterogenous oligomers. Aqueous solutions of norfuraneol and glyoxal exceeded the color formation of all other model reaction systems and it could be shown that the initial reactants as well as their degradation products were incorporated into the colorants. The colored oligomers described herein were composed of carbohydrate-based intermediates of the Maillard reaction and defined as melanoidin precursors or pre-melanoidins.

Key volatile compound formation of rapeseed oil induced via the Maillard reaction during seed roasting

This study was designed to investigate the influence of roasting (150 °C for 0–60 min) on key volatile compounds, sensory evaluation, free amino acids, sugars, and Maillard reaction products (MRPs) of five rapeseed varieties and their oils. During the roasting process, key volatile MRPs of fragrant rapeseed oils (FROs) that increased obviously in concentration were mainly pyrazines. After 60 min of roasting, the stronger nutty-like odor in oil from QH was possibly caused by the high levels of 2,5-dimethylpyrazine (21.72 mg/kg) and 3-ethyl-2,5-dimethylpyrazine (5.06 mg/kg). The 5-hydroxymethylfurfural contents and browning indices increased significantly, whereas reducing sugar and free amino acid contents decreased significantly (p < 0.05). This suggested the extent of the Maillard reaction increased with roasting time. Furthermore, the results of Maillard reaction model system demonstrated glycine, lysine, and histidine could react with glucose to generate 2,5-dimethylpyrazine. Hence, 2,5-dimethylpyrazine is identified as one of the important aroma-active MRPs for FRO.

Voltammetric Mapping of Hydrogen Evolution Reaction on Pt Locally via Scanning Electrochemical Cell Microscopy.

The advancement in nanoscale electrochemical tools has offered the opportunity to better understand heterogeneity at electrochemical interfaces. Scanning electrochemical cell microscopy (SECCM) has been increasingly used for revealing local kinetics and the distribution of active sites in electrocatalysis. Constant-contact scanning and hopping scanning are the two commonly used modes. The former is intrinsically faster, whereas the latter enables full voltammetry at individual locations. Herein, we revisit a less used mode that combines the advantages of hopping and constant-contact scan, resulting in a faster voltammetric mapping. In this mode, the nanodroplet cell in SECCM maintains contact with the surface during the scanning and makes intermittent pauses for local voltammetry. The elimination of frequent retraction and approach greatly increases the speed of mapping. In addition, iR correction can be readily applied to the voltammetry, resulting in more accurate measurements of the electrode kinetics. This scanning mode is demonstrated in the oxidation of a ferrocene derivative on HOPG and hydrogen evolution reaction (HER) on polycrystalline Pt, serving as model systems for outer-sphere and inner-sphere electron transfer reactions, respectively. While the kinetics of the inner-sphere reaction is consistent spatially, heterogeneity is observed for the kinetics of HER, which is correlated with the crystal orientation of Pt.

Gallic Acid Mitigates 5-Hydroxymethylfurfural Formation while Enhancing or Preserving Browning and Antioxidant Activity Development in Glucose/Arginine and Sucrose/Arginine Maillard Model Systems.

The current trend of lowering 5-hydroxymethylfurfural (5-HMF) dietary exposure is challenging since its formation is parallel with the development of food color, flavor and aroma. We aimed to investigate the effect of gallic acid (GA) addition on 5-HMF formation, color development and antioxidant activity (AA) in a series of Maillard Reaction (MR) model systems. The effects of GA addition on browning and AA development were not uniform for all model systems, but always occurred in the same direction, indicating that these phenomena were interconnected. GA mitigated 5-HMF development in four of the nine tested systems, possibly by preventing the oxidation of MR intermediates. Correlation analysis indicated that when GA addition mitigated 5-HMF formation, browning was either promoted or not affected. The proposed strategy was effective for glucose/arginine and sucrose/arginine systems, since GA mitigated 5-HMF formation (49% and 54%, respectively) in addition to increasing color development and antioxidant activity.