Maillard Reaction Model System Research Articles

Generating Maillard reaction products in a model system of d-glucose and l-serine by continuous high-intensity ultrasonic processing

Abstract In this paper, a continuous ultrasonic processing system was established and firstly applied to a Maillard reaction (MR) model system of d -glucose and l -serine. Furthermore, the effects of high-intensity ultrasound assisted MR were compared with those of thermally induced MR through kinetic modelling. The ultrasonic MR had higher depletion rates of reactants as well as higher generation rates of intermediate and final MR products (MRPs) at relatively low processing temperatures (55 and 60 °C). However, both rates were lower for ultrasonic MR than thermal MR when the temperature was raised to 70 and 75 °C. Moreover, the ultrasonic MR had significantly lower activation energy compared with thermal MR. Lastly, three pyrazines, two amines and five O-containing flavour compounds were only produced in ultrasonic MR, not in thermal MR. The difference in flavour generation was attributed to the extremely high, albeit momentary, temperature and pressure condition produced by high-intensity ultrasound. Industrial relevance Ultrasound-assisted processing, a novel technology for non-thermal processing, has been utilized as an alternative to conventional thermal processing. High, albeit momentary, temperature and pressure that are generated by high-intensity ultrasound during processing provide a favourable environment for a number of chemical reactions. Moreover, strong shear stress, turbulence and agitation are among the unique characteristics generated by high-intensity ultrasound, which help to keep excellent mixing during food processing. In our study, a continuous ultrasonic processing system was established so as to achieve a good temperature control as well as to minimize the loss of volatile products during processing, which are major concerns to any liquid-based processing with ultrasound. Furthermore, a Maillard reaction (MR) model system of d -glucose and l -serine under the continuous ultrasonic processing were studied and compared to the most common batch processing of thermal MR through kinetic investigation at the same processing temperature and time conditions. The kinetic models that focused on reactants, intermediates, and final MR products (i.e. melanoidins and flavour compounds), and the kinetic parameters obtained for the MR system may enable controlling the reaction at industrial scale. The different flavour profile that was generated in ultrasonic MR points to new approaches to the food flavour industry to produce more alternatives and varieties.

Evidence for inhibition of nitric oxide and inducible nitric oxide synthase in Caco-2 and RAW 264.7 cells by a Maillard reaction product [5-(5,6-dihydro-4H-pyridin-3-ylidenemethyl)furan-2-yl]-methanol

We have recently isolated and characterized the chemical structure of a bioactive Maillard reaction product, [5-(5,6-dihydro-4H-pyridin-3-ylidenemethyl)furan-2-yl]-methanol (F3-A), from an aqueous glucose (Glc) and lysine (Lys) Maillard reaction (MR) model system. Here, we investigate further the mechanisms for anti-inflammatory effects of this product in Caco-2 and RAW 264.7 cells. The anti-inflammatory capacity of F3-A recovered from Glc-Lys MR mixture and a synthesized product were compared with those of the specific inducible nitric oxide synthase (iNOS) inhibitor, aminoguanidine (AG), and the nuclear factor-kappa B (NF-κB) inhibitor, pyrrolidine dithiocarbamate(PDTC). F3-A produced a dose-dependent inhibition of extracellularnitric oxide (NO) production and iNOS translation in Caco-2 cells induced with interferon gamma(IFN-γ) and phorbol 12-myristate 13-acetate(PMA), and these effects were more potent than those obtained with AG. Moreover, a combination of F3-A and AG to attenuate intestinal inflammation was additive. However, F3-A inhibited only intracellular NO production in RAW 264.7 cells and did not inhibit COX-2 or NF-κB in either cell line. We conclude that the anti-inflammatory properties of F3-A are cell specific, working through different mechanism between macrophages and intestinal cells.

Elucidation of the Chemical Structure and Determination of the Production Conditions for a Bioactive Maillard Reaction Product, [5-(5,6-Dihydro-4H-pyridin-3-ylidenemethyl)furan-2-yl]methanol, Isolated from a Glucose–Lysine Heated Mixture

We previously isolated a bioactive molecule, named F3-A, from an aqueous glucose (Glc) and lysine (Lys) Maillard reaction (MR) model system. Herein, F3-A was verified as [5-(5,6-dihydro-4H-pyridin-3-ylidenemethyl)furan-2-yl]methanol (5) and was subsequently synthesized for confirmation of bioactivity. Using Taguchi and factorial designs, we determined that the conditions which best increased the yield of F3-A were at pH 6 with a sugar:amino acid ratio of 2:1 and heating time of 12 h at 100 °C. The MR mixtures containing glucose produced highest yield, compared to fructose, lactose, and sucrose. Both the F3-A recovered from Glc-Lys MR mixture and the synthesized product exhibited significant (P < 0.05), dose dependent, nitric oxide (NO) inhibitory activity in Caco-2 cells that was comparable to aminoguanidine (AG) and pyrrolidine dithiocarbamate (PDTC), respectively. Finally, an additional inhibitory effect of F3-A was determined when coincubated with AG in cytokine-induced Caco-2 cells. This bioactivity points to a potential role in preventing intestinal inflammation.

Formation and reduction of carcinogenic furan in various model systems containing food additives

The aim of this study was to analyse and reduce furan in various model systems. Furan model systems consisting of monosaccharides (0.5M glucose and ribose), amino acids (0.5M alanine and serine) and/or 1.0M ascorbic acid were heated at 121°C for 25min. The effects of food additives (each 0.1M) such as metal ions (iron sulphate, magnesium sulphate, zinc sulphate and calcium sulphate), antioxidants (BHT and BHA), and sodium sulphite on the formation of furan were measured. The level of furan formed in the model systems was 6.8–527.3ng/ml. The level of furan in the model systems of glucose/serine and glucose/alanine increased 7–674% when food additives were added. In contrast, the level of furan decreased by 18–51% in the Maillard reaction model systems that included ribose and alanine/serine with food additives except zinc sulphate.

Formation and reduction of furan in maillard reaction model systems consisting of various sugars/amino acids/furan precursors.

To investigate the effect of the temperature on the formation of furan, various furan models were conducted at 90, 121, and 150 °C. A total 15 models, including alanine (ALA), serine (SER), ribose (RIB), RIB/ALA, RIB/SER, glucose (GLU), GLU/ALA, GLU/SER, sucrose (SUC), SUC/ALA, SUC/SER, furoic acid (FUR), GLU/FUR, acetaldehyde (ACET), and GLU/ACET, were prepared. The maximum level of furan was detected in the GLU/SER and GLU/ALA models at a molar ratio of 0.5:0.5. The formation of furan was proportional to the temperature in all models. The RIB/SER model generated the greatest amount of furan among the 11 models ranging from 2.1 to 4931.9 ng mL(-1) under all temperature conditions. Among the precursor models, the FUR model formed the greatest amount of furan ranging from 1058.2 to 13 927.9 ng mL(-1) at all temperatures.

Optimised formation of blue Maillard reaction products of xylose and glycine model systems and associated antioxidant activity

A blue colour can be formed in the xylose (Xyl) and glycine (Gly) Maillard reaction (MR) model system. However, there are fewer studies on the reaction conditions for the blue Maillard reaction products (MRPs). The objective of this study is to investigate characteristic colour formation and antioxidant activities in four different MR model systems and to determine the optimum reaction conditions for the blue colour formation in a Xyl-Gly MR model system, using the random centroid optimisation program. The blue colour with an absorbance peak at 630 nm appeared before browning in the Xyl-Gly MR model system, while no blue colour formation but only browning was observed in the xylose-alanine, xylose-aspartic acid and glucose-glycine MR model systems. The Xyl-Gly MR model system also showed higher antioxidant activity than the other three model systems. The optimum conditions for blue colour formation were as follows: xylose and glycine ratio 1:0.16 (M:M), 0.20 mol L⁻¹ NaHCO₃, 406.1 mL L⁻¹ ethanol, initial pH 8.63, 33.7°C for 22.06 h, which gave a much brighter blue colour and a higher peak at 630 nm. A characteristic blue colour could be formed in the Xyl-Gly MR model system and the optimum conditions for the blue colour formation were proposed and confirmed.

Simultaneous Analysis of Acrylamide and Its Key Precursors, Intermediates, and Products in Model Systems by Liquid Chromatography–Triple Quadrupole Mass Spectrometry

A new analytical setup allowing the simultaneous analysis of precursors, intermediates and products in Maillard reaction model systems was developed to investigate the formation and mitigation kinetics of acrylamide. It was based on high-performance liquid chromatography combined with electrospray ionization triple quadrupole tandem mass spectrometry (HPLC-MS/MS). Chromatography and mass spectrometry conditions were optimized to permit simultaneous monitoring of compounds relevant to acrylamide, such as asparagine, glucose, glycine, N-(1-deoxy-D-fructos-1-yl)-glycine (DFG), N-(1-deoxy-D-fructos-1-yl)-asparagine (DFA), and four reaction products between acrylamide and glycine. A fairly good separation was achieved on a Venusil MP-C18 column using an isocratic eluent of 0.5% formic acid in water at a flow rate of 0.4 mL/min. Triple quadrupole mass spectrometry in multiple reaction monitoring mode (MRM) was applied to obtain good sensitivity. All of the ten key reaction compounds were separated and determined in a single run within 15 min. High correlation coefficients (r > 0.99) of the ten analytes were obtained in their respective linear ranges. The method was capable to accurately quantify the ten key compounds in model systems during heating. The results showed that acrylamide formed in Maillard reaction could be reduced by reacting directly with glycine, and acrylamide concentration constantly decreased by about 60% within the 180 min heating at 150 °C when glycine was equal to asparagine and glucose in molecular concentration in model systems. This method helps achieve reduction in both time and labor of analysis of a large number of samples.

Hydroxyl radical induced by lipid in Maillard reaction model system promotes diet-derived Nε-carboxymethyllysine formation

N(ε)-carboxymethyllysine (CML) is commonly found in food, and is considered as a potential hazard to human health. However, the effect of lipids on CML formation in Maillard reaction is still not clarified. In this study, the content of diet-derived CML and its key intermediates, epsilon-fructoselysine (FL) and glyoxal (GO), is determined with high performance liquid chromatography mass spectrum (HPLC-MS) in model system containing lipid compounds. According to the results, hydroxyl radical (OH) induced by Fenton reagent can promote the three pathways of CML formation. Moreover, in the Maillard reaction system, linoleic acid (Lin), oleic acid (Ole) and glycerol trioleate (Tri) can induce more OH·, which promotes CML formation. Their level of promoting CML formation is in the order of Ole>Lin>Tri. On the contrary, glycerol (Gly) can scavenge OH·, which inhibit the CML formation. Finally, it is proved that FL content and GO content decreases with heating time in model system, while CML content increases with heating time. Thus, it is concluded that in the Maillard reaction system lipids can induce more OH·, which promotes the conversion from FL and GO to CML. Our research may contribute to the development of inhibitory methods for diet-derived CML by scavenging OH·.

Inhibition of heterocyclic amine formation by water-soluble vitamins in Maillard reaction model systems and beef patties

Abstract The inhibitory activities of 11 water-soluble vitamins against heterocyclic amine formation were examined in a PhIP and a MeIQx producing chemical model. Six investigated vitamins (pyridoxiamine, pyridoxine, nicotinic acid, biotin, thiamine and l -ascorbic acid) out of the 11, exhibited significant inhibition (>40%) in both models. Pyridoxamine was the most potent inhibitor, and its inhibitory effect increased with increasing concentration in the model, although not in a linear manner. The activity of pyridoxamine, niacin and ascorbic acid was investigated using fried beef. Moderate inhibition (∼20%) of the formation of PhIP, 4,8-DiMeIQx and MeIQx was found for niacin and ascorbic acid; whereas pyridoxamine reduced the levels of all three HAs by ∼40%. GC–MS analysis showed that pyridoxamine significantly reduced the level of PhIP intermediate, phenylacetaldehyde. LC–ESI–MS/MS analysis revealed that pyridoxamine directly reacts with phenylacetaldehyde to form an adduct, whose structure was characterised by MS and NMR spectroscopy.

Changes in the initial stages of a glucose-proline Maillard reaction model system influences dairy product quality during thermal processing

The Maillard reaction always occurs during the thermal processing of dairy products, which significantly influences their quality. In the present study, the initial stages of a glucose-proline model system were investigated in water and different types of buffer solutions. Results showed that phosphate buffer accelerated the reversible degradation of the initial stages of the reaction. The proposed catalysis mechanism was that hydrogenous and dihydric phosphate radical anions simultaneously accepted and donated protons for the conversion of the intermediates into N-glycosylamine. The catalysis mechanism was confirmed via testing and no reducing of hydrogenous and dihydric phosphate radical anions was observed during the reaction. Moreover, both N-(1-deoxy-d-fructos-1-yl)proline and its degradation compounds were analyzed. Results showed that degradation of N-(1-deoxy-d-fructos-1-yl)proline to form 5-hydroxymethyl-2-furaldehyde and formic acid was also accelerated by phosphate buffer. An interesting phenomenon was that citrate decreased 5-hydroxymethyl-2-furaldehyde formation, which might be because Strecker-type degradation occurred more easily than 1,2-enolization reaction in citrate buffer solution. However, this hypothesis has not been confirmed, and element label experiments should be carried out in the future.

Characterization of antioxidant and anti-inflammatory activities of bioactive fractions recovered from a glucose−lysine Maillard reaction model system

A glucose-lysine (Glu-Lys) Maillard reaction mixture heated at 121°C for 60 min was processed by ultrafiltration, ethyl acetate extraction, and semi-preparative HPLC to recover a bioactive fraction, termed F3. F3, characterized by spectral analysis to contain three distinct components, inhibited NO and IL-8 by 70 and 61%, respectively, at a concentration of 50 μg/ml in inflamed Caco-2 cells induced by IFN-γ and phorbol 12-myristate 13-acetate (PMA). F3 significantly (P < 0.05) down-regulated several genes involved in nuclear factor kappa B (NF-κB) signaling pathway. These genes included the cytokine receptors, TNFRSF10A and TNFRSF10B; receptor-associated proteins, IRAK2 and TICAM1; the inhibitor κB kinase, IKBKE; the NF-κB inhibitor, NFKBIA; and the NF-κB subunits, REL, RELA, and RELB. F3 also down-regulated the NF-κB responsive genes IL-8, NOS2, and ICAM1, attenuated the gene expression of peroxidases such as DUOX1 and DUOX2, and relieved the down-regulated GCFHR that are involved in the biosynthesis of NO and TROAP, a gene suppressed by NO. The anti-inflammatory activity of F3 was mediated through multiple processes that included regulation of gene expressions involved in NF-κB signaling, the inhibition of IL-8 and iNOS translation, a decrease in NO synthesis and attenuating oxidative stress in inflamed Caco-2 cells. Our results show that MRP components have the potential to suppress inflammation in IFN-γ and PMA-induced Caco-2 cells.

Identification and quantification of α-dicarbonyl compounds produced in different sugar-amino acid Maillard reaction model systems

A mixture of α-dicarbonyl compounds generated from Maillard reaction (MR) model systems, comprising of fructose with glycine (Fru-Gly) and lysine (Fru-Lys); glucose with glycine (Glu-Gly) and lysine (Glu-Lys); ribose with glycine (Rib-Gly) and lysine (Rib-Lys), were identified and quantified. α-Dicarbonyl compounds generated in the hexose models were predominantly glucosone and 3-deoxyglucosone (3-DG), with 3-deoxypentosone (3-DP) and pentosone being the major α-dicarbonyls produced in the pentose models. Ethyl acetate extraction of model MRPs resulted in poor recovery of 2,3-diaminonaphthalene benzoquinoxalines of glucosone, 3-DG, pentosone, 3-DP and methylglyoxal (MGO), respectively. The temporal profiles of pentosone, 3-DP, glyoxal (GO) and MGO were similar in the pentose models, with maximum concentration occurring within 5 min. These four α-dicarbonyl compounds were higher ( P < 0.05) in Rib-Gly than in Rib-Lys MR systems. The quantity of α-dicarbonyl compounds was affected by the interaction among the type of sugar and amino acid and the reaction time. The type of sugar is the most important factor that affected both the quantity and quality of α-dicarbonyl compounds produced in MR mixtures.

Correlating Changes That Occur in Chemical Properties with the Generation of Antioxidant Capacity in Different Sugar‐Amino Acid Maillard Reaction Models

We investigated the development of antioxidant activity relative to the change of pH, fluorescent intensity, ultraviolet (UV) absorbance (A294), browning (A420), and alpha-dicarbonyl compounds in sugar-amino acid Maillard reaction (MR) model systems comprising fructose, glucose, or ribose each with glycine (Fru-Gly, Glu-Gly, and Rib-Gly) or lysine (Fru-Lys, Glu-Lys, and Rib-Lys), respectively, which were heated at 121 °C for 5 to 90 min. For hexose models, the change in pH was shown to fit a second-order polynomial regression with A294 and A420. Antioxidant activity was significantly and positively correlated with UV absorbance (r = 0.905, P < 0.001) and browning products (r = 0.893, P < 0.001) rather than with fluorescent products or the alpha-dicarbonyl compounds. Type of sugar was most important in evoking a change in UV absorbance, browning, alpha-dicarbonyl compounds, and antioxidant activity of MR products (MRPs). In conclusion, the antioxidant activity of MRPs in six model systems was more closely associated with products derived at the intermediate-to-late stages of the reaction and influenced mostly by the type of sugar. We report on the different factors and their interactions that are important for understanding the functional attributes of food components that comprise the generation of Maillard browning products and the associated antioxidant activities generated during high-temperature food processing.

Formation of Carcinogenic 4(5)-Methylimidazole in Maillard Reaction Systems

4(5)-Methylimidazole has received the attention of federal and state regulatory agencies because of its carcinogenicity and common presence in foods and beverages. In the present study, the formation of 4(5)-methylimidazole in Maillard reaction model systems consisting of D-glucose/NH(3), L-rhamnose/NH(3), methylglyoxal/NH(3), and methylglyoxal/formaldehyde/NH(3) was investigated. 4(5)-Methylimidazole was formed at levels ranging from 0.49 to 0.71 mg/mL in the d-glucose/NH(3) model system. The formation of 4(5)-methylimidazole was slightly higher in the L-rhamnose/NH(3) system (0.91 mg/mL) than in the d-glucose/NH(3) system (0.71 mg/mL) under the conditions used in the present study. A methylglyoxal/NH(3) system produced significantly higher levels of 4(5)-methylimidazole (5.70 mg/mL), suggesting that methylglyoxal is an important precursor of 4(5)-methylimidazole. Ammonolysis of methylglyoxal, which is one of the glucose degradation products, was proposed to form formamide, which subsequently reacted with 2-aminopropanal (α-aminocarbonyl intermediate) formed from methylglyoxal to give 4- or 5-methylimidazole. The levels of 4(5)-methylimidazole found in commercial cola soft drinks range from 0.30 μg/mL (brand 3) to 0.36 μg/mL (brands 1 and 5).

Acrylamide in Foods: Chemistry and Analysis. A Review

Acrylamide is a potential cause of a wide spectrum of toxic effects and is classified as probably “carcinogenic in humans”. The discovery of acrylamide in human foods has given rise to extensive studies exploring its formation mechanisms and levels of exposure and has spurred search into suitable analytical procedures for its determination in foodstuffs. However, the exact chemical mechanisms governing acrylamide formation are not yet known and cheap, convenient, and rapid screening methods are still to be developed. Acrylamide in food is produced by heat-induced reactions between the amino group of asparagine and the carbonyl group of reducing sugars along with thermal treatment of early Maillard reaction products (N-glycosides). Similarly, the decarboxylated Schiff base and decarboxylated Amadori compounds of asparagine as well as the Strecker aldehyde have been proposed as direct precursors and intermediates of acrylamide. Corresponding chromatographic methods are used to determine various structural groups present in Maillard reaction model systems. Gas chromatography-mass spectrometry and liquid chromatography with tandem mass spectrometry analysis are both acknowledged as the main, useful, and authoritative methods for acrylamide determination. This review is an attempt to summarize the state-of-the-art knowledge of acrylamide chemistry, formation mechanisms, and analytical methods. Special attention is given to comparison of different chromatographic techniques, particularly the novel, simple, and low-cost methods of its determination.

Antioxidant activity of Maillard reaction products

European Journal of Lipid Science and TechnologyVolume 111, Issue 2 p. 109-111 EditorialFree Access Antioxidant activity of Maillard reaction products Ryszard Amarowicz, Ryszard Amarowicz Division of Food Science, Institute of Animal Reproduction and Food Research, Polish Academy of Sciences, Olsztyn, PolandSearch for more papers by this author Ryszard Amarowicz, Ryszard Amarowicz Division of Food Science, Institute of Animal Reproduction and Food Research, Polish Academy of Sciences, Olsztyn, PolandSearch for more papers by this author First published: 17 February 2009 https://doi.org/10.1002/ejlt.200900011Citations: 63AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. References 1 L. Manzocco, S. Calligaris S., D. Mastrocola, M. C. Nicoli, C. R. Lerici: Review of non-enzymatic browning and antioxidant capacity in processed foods. Trends Food Sci Technol. 11, 340– 346. 2 B. Ruiz-Roca, M. P. Navarro, I. Seiquer: Antioxidant properties and metal chelating activity of glucose-lysine heated mixtures: Relationships with mineral absorption across caco-2 cell monolayers. J Agric Food Chem. 2008, 56, 9056– 9063. 3 M.-N. Billaud, Y.-N. Ordonaud, J. Nicolas: Free radical scavenging, inhibition of polyphenoloxidase activity and copper chelating properties of model Maillard systems. LWT – Food Sci Technol. 2007, 40, 1434– 1444. 4 Y.Osada, T. Shibamoto: Antioxidative activity of volatile extracts from Maillard model systems. Food Chem. 2006, 98, 522– 528. 5 X.-M. Chen, D. D. Kitts: Antioxidant activity and chemical properties of crude and fractionated Maillard reaction products derived from four sugar-amino acid Maillard reaction model systems. Ann NY Acad Sci. 2008, 1126, 220– 224. 6 K. Cejepek, L. Jarolímová, J. Valíšek: Antioxidant capacity of Maillard systems with carbonyl products of sugar fragments. Czech J Food Sci. 2004, 22 SI, 60– 63. 7 J. A. Rufián-Henares, F. J. Morales: Functional properties of melanoidins: In vitro antioxidant, antimicrobial and antihypertensive activities. Food Res Int. 2007, 40, 995– 1002. 8 F. J. Morales, S. Jiménez-Pérez: Peroxyl radical scavenging activity of melanoidins in aqueous systems. Eur Food Res Technol. 2004, 218, 515– 520. 9 G. Sacchetti, C. Di Mattia, P. Pittia, D. Mastrocola: Effect of roasting degree, equivalent thermal effect and coffee type on the radical scavenging activity of coffee brews and their phenolic fraction. J Food Engin. 2009, 90, 74– 80. 10 J. Á. Gómez-Ruiz, J. M. Ames, D.S. Leake: Antioxidant activity and protective effects of green and dark coffee components against human low density lipoprotein oxidation. Eur Food Res Technol. 2008, 227, 1017– 1024. 11 A. Michalska, M. Amigo-Benavent, H. Zielinski, M. D. Del Castillo: Effect of bread making on formation of Maillard reaction products contributing to the overall antioxidant activity of rye bread. J Cereal Sci. 2008, 48, 123– 132. 12 E. M. Peralta, H. Hatate, D. Kawabe, R. Kuwahara, S. Wakamatsu, T. Yuki, H. Murata: Improving antioxidant activity and nutritional components of Philippine salt-fermented shrimp paste through prolonged fermentation. Food Chem. 2008, 111, 72– 77. 13 B. Kusznierewicz, A. Śmiechowska, A. Bartoszek, J. Namieśnik: The effect of heating and fermenting on antioxidant properties of white cabbage. Food Chem. 2008, 108, 853– 861. 14 I. Seiger, B. Riuz-Roca, M. Mesías, A. Muñoz-Hoyos, G. Galdó, J. J. Ochoa, M.P. Navarro: The antioxidant effect of a diet rich in Maillard reaction products is attenuated after consumption by healthy male adolescents. In vitro and in vivo comparative study. J Sci Food Agric. 2008, 88, 1245– 1252. Citing Literature Volume111, Issue2No. 2 February 2009Pages 109-111 ReferencesRelatedInformation

Antioxidant Activity and Chemical Properties of Crude and Fractionated Maillard Reaction Products Derived from Four Sugar–Amino Acid Maillard Reaction Model Systems

Antioxidant activity of Maillard reaction products (MRPs) derived from four sugar-amino acid Maillard reaction model systems (glucose [Glc] or ribose [Rib] reacted with glycine [Gly] and L-lysine [Lys]) were examined in terms of chemical properties and molecular weight fractionation of reaction products. Rib-amino acid model systems produced MRPs with higher antioxidant activity than Glc-amino acid model MRPs (P < 0.05, Rib-Lys > Rib-Gly > Glc-Lys > Glc-Gly). In the same sugar or same amino acid model systems, antioxidant activity of MRPs was negatively related to the final pH, fluorescent intensity, and the content of dicarbonyl compounds. Antioxidant activity positively related to the production of late-stage browning MRPs. Fraction I from the Glc-Lys model system separated by gel filtration chromatography had the highest oxygen radical absorbance capacity (ORAC) value (1736 micromol Trolox/g MRP). Fraction IV from the Rib-Lys model system had a higher ORAC value compared to Fraction III. This result indicated that high molecular weight MRPs do not necessarily have higher antioxidant activity compared to low molecular weight MRPs.

Effects of o-phenylenediamine on methylglyoxal generation from monosaccharide: Comment on “correlation of methylglyoxal with acrylamide formation in fructose/asparagine Maillard reaction model system”

Methylglyoxal (MG), a reactive carbonyl compound, has recently garnered much attention because of its ability to modify proteins over time and yield advanced glycation end products (AGEs) that are thought to contribute to the development of diabetes mellitus and its complications. In a recent paper published in Food Chemistry by Yuan et al. [Yuan, Y., Zhao, G. H., Hu, X. S., Wu, J. H., Liu, J., & Chen, F. (2007a). Correlation of methylglyoxal with acrylamide formation in fructose/asparagines Maillard reaction model system. Food Chemistry, 108(3), 885–890] authors showed a high correlation between methylglyoxal formation and acrylamide formation. However, in their study, model systems of aqueous fructose/asparagines (Fru/Asn) and fructose/asparagines/o-phenylenediamine (Fru/Asn/OPD) heating at 150°C were used. The validity of these models relies on the assumption that OPD will only serve the role of a trapping agent for MG. In this short communication, we would like to call to attention that MG can also have a strong catalytic effect in the generation of MG from fructose. Therefore, it is concluded that the concentration of MG obtained in Fru/Asn/OPD model system cannot correspond to the total amount of MG formed by Maillard reaction of Fru and Asn as claimed by Yuan et al. [Yuan, Y., Zhao, G. H., Hu, X. S., Wu, J. H., Liu, J., & Chen, F. (2007a). Correlation of methylglyoxal with acrylamide formation in fructose/asparagines Maillard reaction model system. Food Chemistry, 108(3), 885–890, Yuan, Y., Zhao, G. H., Hu X. S., Wu, J. H., Liu, J., & Chen. F. (2007b). High correlation of methylglyoxal with acrylamide formation in glucose/asparagine Maillardreaction model. European Food Research and Technology. doi:10.1007/s00217-007-0658-0].

Correlation of methylglyoxal with acrylamide formation in fructose/asparagine Maillard reaction model system

α-Dicarbonyl compounds were highly reactive intermediates formed in Maillard reaction (MR), and o-phenylenediamine (OPD) was widely used as a trapping agent for α-dicarbonyl compounds. Both aqueous fructose/asparagine (Fru/Asn) and fructose/asparagine/o-phenylenediamine (Fru/Asn/OPD) model systems were heated at 150°C for up to 30min. Methylglyoxal (MG) was the main α-dicarbonyl compounds formed in MR, which was chosen as a representative of α-dicarbonyl compound to investigate the influence on acrylamide (AA) formation. The concentrations of AA, MG and Asn were detected during MR by HPLC method. The results indicated that the formation of AA increased with the heating time, and nearly 75% of AA was formed through the participation of α-dicarbonyl compounds. The amounts of formation and consumption of MG increased with heating time, and from 12min of reaction, the consumed amounts of MG accounted for 62.1–90.3% on the basis of total amounts of MG formed in MR, suggesting that most of the MG took part in further reactions. Meanwhile, Asn concentration decreased with heating time in both models. The formation of AA and consumption of Asn were highly correlated with MG. Indeed, as MG concentration in MG/Asn model system decreased during heating at 150°C, the concentration of AA significantly increased. The coefficient of correlation between consumed amounts of MG and the formed amounts of AA was 0.931, demonstrating that MG plays a role in AA formation.

Study on the Hydroxyl Radical Scavenging Activity Changes of Ginseng and Ginsenoside-Rb2 by Heat Processing

The free radical scavenging activities of Panax ginseng C.A. MEYER are known to increase by heat processing. Phenolic acids and Maillard reaction products (MRPs) have been suggested as active free radical scavenging components from our previous research, but heat processing-induced chemical and activity changes of ginsenosides considering the Maillard reaction have not yet been fully elucidated. In this study, we investigated the hydroxyl radical (.OH) scavenging activity changes of ginsengs and ginsenoside-Rb2 (Rb2)) by heat processing using an electron spin resonance spectrometer. Especially, Rb2 was heat processed with the same amount of glycine, a frequently used amino acid in the Maillard reaction model system. As a result, the .OH scavenging activities and brown compound levels of ginseng and glycine-Rb2 mixture were increased by heat processing. However, the increase in .OH scavenging activities were not in accordance with the extents of browning. On the other hand, less-polar ginsenosides such as Rg3, Rg5, and Rk1 were generated from the glycine-Rb2 mixture by heat processing. The sugar moieties at carbon-20 of Rb2 were separated by the steaming process, less-polar ginsenosides were produced, and then the separated sugar moieties were thought to form MRPs with glycine. From the .OH scavenging activity tests of Rb2, glycine, less-polar ginsenosides, and maltol, the increase in .OH scavenging activity was thought to be more closely related to the generation of .OH scavenging ginsenosides such as 20(S)-Rg3 and Rg5 by heat processing than MRPs.