Glycine Maillard Reaction Research Articles

Maillard Browning Inhibition by Ellagic Acid via Its Adduct Formation with the Amadori Rearrangement Product.

The Maillard reaction performed under a stepwise increase of temperature was applied for researching the inhibition of Maillard browning caused by ellagic acid. Ellagic acid was found effective for the inhibition of melanoidin formation in the xylose-glycine Maillard reaction but depended on its dosage and the point of time it was added in the reaction system. The lightest color of the Maillard reaction products was observed when ellagic acid was added at the 90th min, which was the point of time when the Amadori rearrangement product (ARP) developed the most. LC-ESI-MS/MS analysis results showed a significant tendency of the ellagic acid hydrolysis product to react with the predominant intermediate ARP to yield an adduct. The adduct stabilized the ARP and delayed its decomposition and inhibited the downstream reactions toward browning. After the ARP was depleted, ellagic acid also showed an effect on scavenging some short-chain dicarbonyls which contributed to the inhibition of Maillard browning.

Effects of high-intensity ultrasound and oil type on the Maillard reaction of d-glucose and glycine in oil-in-water systems

This study addresses the effect of high-intensity ultrasonic processing on four oil-in-water systems, using sunflower, peanut, olive and flaxseed oils, respectively, that contained an aqueous d-glucose and glycine Maillard reaction (MR) model system. The MR in the water phase was promoted as observed from higher depletion of reactants and higher amount of MR products (MRPs). A significantly higher amount of pyrazines was generated after ultrasonic processing, particularly in the sunflower and olive oil systems. These promotions were attributed to a well-mixing effect and a localised high temperature and pressure environment generated by the high-intensity ultrasound. However, upon 1 h of ultrasonic processing at 80 °C, a significant increase of oxidation was observed with high peroxide and p-anisidine values in the post-processed oils; meanwhile, the amount of unsaturated fatty acids decreased as well. As a result, some off-flavours were also detected in the post-processed oils, which affected the overall flavour profile of the MR systems.

Optimized preparation, characterization, and antioxidant activity of chitooligosaccharide-glycine Maillard reaction products.

In this study, chitooligosaccharide (COS) and glycine (Gly) were selected to prepare Maillard reaction products, which were designated COS-Gly-MRPs. Changes in the FTIR and fluorescence spectra confirmed the formation of the COS-Gly-MRPs. Using ferric reducing antioxidant power (FRAP) as a response, the optimal reaction conditions, i.e., a time of 107min, temperature of 121°C, pH of 6.0, and nCOS:nGly=2.5:1, were obtained by one-variable-at-a-time method and by response surface methodology. The resulting COS-Gly-MRPs exhibited much stronger antioxidant activity than their substrates. The FRAP of COS-Gly-MRPs was 32.14mmol Fe2+/L, and the radical scavenging activity of COS-Gly-MRPs reached 78.6, 89.0, 92.3, and 86.0% for ABTS, superoxide, DPPH, and hydroxyl radicals, respectively. After 7days of storage, COS-Gly-MRPs-treated fruit juices showed higher antioxidant capacity than those treated with a mixture of COS and Gly.

DFT studies on fructose and glycine maillard reaction: Formation of the heyns rearrangement products in the initial stage

DFT studies on the proposed mechanisms of the initial stage of Maillard reaction between α-fructose (α-Fru)/β-fructose (β-Fru)/open chain fructose (O-Fru) and glycine (Gly) under different conditions revealed that α-Fru was more reactive than β-Fru and O-Fru, and O-Fru was less reactive than β-Fru in the reaction. The reaction under basic conditions was found to be the most favorable for the formation of the Heyns rearrangement products (HRPs) in the initial stage, and the aqueous solution was found to be more feasible than the gaseous state reaction. The reaction under neutral conditions was the second most favorable for the production of HRPs. The reaction at the isoelectric point of glycine and under acidic conditions was found to be unfeasible to produce HRPs.

The ribose and glycine Maillard reaction in the interstellar medium (ISM): A theoretical study

Possibility of the Maillard reaction to take place in the gaseous phase in the interstellar medium was investigated by using Density Functional Theory (DFT) computations. Cyclic ribose (c-Rib)/open-chain ribose (c-Rib) and glycine were taken as the model. Mechanisms have been proposed, and possibility of the formation of different compounds have been evaluated through calculating the Gibb’s free energy changes for different steps of the reaction by following the total mass balance. The result reveals that both c-Rib and Rib can participate in the reaction, and c-Rib is more efficient than Rib. The reactions under basic and neutral conditions are supposed to be the first and second most favourable. Acidic conditions and the isoelectric point of glycine were unfeasible for the reaction. The kinetics of the mechanics are briefly addressed in this work.

Density functional computational studies on the glucose and glycine Maillard reaction: Formation of the Amadori rearrangement products

AbstractTheoretical energy changes of various intermediates leading to the formation of the Amadori rearrangement products (ARPs) under different mechanistic assumptions have been calculated, by using open chain glucose (O‐Glu)/closed chain glucose (A‐Glu and B‐Glu) and glycine (Gly) as a model for the Maillard reaction. Density functional theory (DFT) computations have been applied on the proposed mechanisms under different pH conditions. Thus, the possibility of the formation of different compounds and electronic energy changes for different steps in the proposed mechanisms has been evaluated. B‐Glu has been found to be more efficient than A‐Glu, and A‐Glu has been found more efficient than O‐Glu in the reaction. The reaction under basic condition is the most favorable for the formation of ARPs. Other reaction pathways have been computed and discussed in this work. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2008

Density functional computational studies on the intermediate stage of the ribose and glycine Maillard reaction: Formation of deoxyosones in aqueous solution

Mechanisms in an aqueous solution of the Maillard reaction are proposed under several pH conditions for the interaction of glycine with cyclic ribose (c-Rib) and open-chain ribose (Rib). According to the Gibbs free energy relationships as well as internal energies values derived from our density functional theory calculations, the c-Rib/Rib + DGly (glycine) are the most favourable reaction pathways for the formation of deoxyosones under basic conditions, where Rib is more reactive than c-Rib. The intermediate stage of the Maillard reaction leads to the formation of deoxyosones.

Density functional computational studies on ribose and glycine Maillard reaction: Formation of the Amadori rearrangement products in aqueous solution

By following the Hodge-scheme, and considering the formation of the Amadori rearrangement products ( ARPs) as one of the possible intermediates in the early stage, density functional theory calculations have been performed at the standard state on the proposed mechanisms of the Maillard reaction of cyclic ribose ( c-Rib)/open-chain ribose ( Rib) and glycine species under different pH conditions in aqueous solution. The result reveals that both c-Rib and Rib can participate in the reaction. Rib has been found as more reactive than c-Rib in the reaction. The reactions under basic and neutral conditions are supposed to be the most and second most favourable for the formation of ARPs. Production of both of the enol and keto forms of ARP have been found as feasible under basic condition, whereas the neutral condition is only favourable for producing the enol form of ARP. Therefore, the rate of browning under basic condition is assumed higher than that of the neutral condition. Formation of all intermediates in the proposed mechanisms has been found as unfeasible in the reaction under acidic condition and at the isoelectric point of glycine. Therefore, production of ARPs under these conditions is assumed to be stalled under these conditions, resulting into lower browning rate. Formation of Rib through the cleavage of glucose has been assumed less feasible than the formation of glucose from Rib and formaldehyde in aqueous solution.

Formation of pyrazines in dihydroxyacetone and glycine Maillard reaction: A computational study

Based on the electronic and Gibb’s free energy changes, the possibility of the formation of 2,5-dimethyl pyrazine ( 25Pz) as one of the probable final products in dihydroxyacetone ( DHA) and glycine Maillard reaction under different pH conditions is described. Mechanisms for the reaction have been proposed following the Hodge-scheme. Density functional computational calculations at the standard state have been performed on the proposed mechanisms of the reaction. Electronic and Gibb’s free energy changes for the formation of different compounds have been estimated by following the total mass balance for different steps of the reaction. The possible order of feasibility for the production of 25Pz has been found as DHA + deprotonated glycine ( DGly) gaseous > DHA + DGly aqueous > DHA + unprotonated glycine ( UGly) gaseous > DHA + glycine zwitterion ( GlyZ) gaseous > DHA + UGly aqueous > DHA + GlyZ aqueous > DHA + protonated glycine ( PGly) aqueous > DHA + PGly gaseous phase reactions. Amino-acetone has been found to be the most likely precursor of the pyrazine ring. Oxidation plays an important role during the production of 25Pz. Water has been found as a by-product during the formation of 25Pz.

Formation of methyl glyoxal in dihydroxyacetone and glycine Maillard reaction: A computational study

By considering the formation of methyl glyoxal as one of the possible intermediates, mechanisms for the intermediate stage of the Maillard reaction of dihydroxyacetone and glycine under different pH conditions have been proposed, following the Hodge-scheme. Density functional theory calculations have been performed at the standard state on the proposed mechanisms to calculated the Gibb’s free energy changes for the formation of different compounds in different steps of the reaction. Thus, the possibility for the formation of different compounds in the proposed mechanisms has been evaluated. Electronic energy changes for the formation of different compounds in the proposed mechanisms have been calculated to observe the internal energy changes of the reaction. The total mass balance has been followed during the calculation of electronic and Gibb’s free energies. The result reveals that methyl glyoxal is one of the most likely intermediates in the reaction, and dihydroxyacetone + deprotonated glycine and dihydroxyacetone + unprotonated glycine reactions are assumed favorable for the production of methyl glyoxal. The gaseous phase reaction is supposed to be more feasible than the aqueous phase reaction for the production of methyl glyoxal. Glyceraldehyde + protonated glycine and glyceraldehyde + glycine zwitterion reactions are postulated as less feasible for the formation of methyl glyoxal.

Formation of the Heyns rearrangement products in dihydroxyacetone and glycine Maillard reaction: A computational study

Density functional theory computations at the standard state on the proposed mechanisms of dihydroxyacetone and glycine Maillard reaction under different pH conditions have revealed that dihydroxyacetone + deprotonated glycine and dihydroxyacetone + unprotonated glycine reactions are more favorable than dihydroxyacetone + protonated glycine and dihydroxyacetone + glycine zwitterion reactions for the formation of the Heyns rearrangement products ( HRPs). The gaseous phase reaction is assumed more feasible than the aqueous phase reaction for the production of HRPs. Due to the possibility of the production of both of the enol and keto forms of HRPs, the rate of browning in the dihydroxyacetone + deprotonated glycine reaction is assumed higher than that of the others. Dihydroxyacetone + protonated glycine and dihydroxyacetone + glycine zwitterion reactions are not favorable for the formation of HRPs and, therefore, the reaction is assumed hindered under these conditions and the rate of browning is supposed to be lower than that of the others. Possibilities for the conversion of dihydroxyacetone to glyceraldehyde and formation of hydroxyacetaldehyde from dihydroxyacetone as a C2-fragmentation product have also been evaluated.

Effects of Water Content on Volatile Generation and Peptide Degradation in the Maillard Reaction of Glycine, Diglycine, and Triglycine

Peptides abundant in food and protein hydrolysates are known to be important to process flavors. The present study reports the volatile profile of the Maillard reactions of glycine, diglycine, and triglycine. The reaction with glucose was conducted at 0-100% water content in glycerol medium at 160 degrees C for 1 h. Volatile compounds were quantified by stir bar sorptive extraction-gas chromatography-mass spectrometry, and nonvolatile compounds were quantified by high-performance liquid chromatography-tandem mass spectrometry. The major volatiles produced from each of the reaction systems were trimethylpyrazine and 2,5-dimethylpyrazine. Volatile generation increased as water decreased, and the overall reactivity of the glycine and glycine peptides in volatile formation was glycine approximately triglycine > diglycine. Triglycine was very unstable and mainly degraded into cyclic Gly-Gly and glycine, whereas diglycine had a higher stability than triglycine toward hydrolytic cleavage of the peptide bond. The amounts of glycine, diglycine, cyclic (Gly-Gly), and triglycine in the peptide-glucose reaction mixtures at different water content were reported.

Computational studies on glyceraldehyde and glycine Maillard reaction—III

By considering the formation of 2,5-dimethyl pyrazine as one of the possible final product, Density Functional Theory calculations have been performed at the standard state on the proposed mechanisms for the final stage of glyceraldehyde and glycine Maillard reaction under different conditions. Δ G 0 and Δ E 0 of different steps have been calculated by following the total mass balance. Thus, possibility of the formation of different intermediates, and different steps to take place, has been evaluated. Glyceraldehyde+deprotonated glycine reaction has been found to be the most favorable for the formation of 2,5-dimethyl pyrazine in both of the gaseous and aqueous states, and especially in the gaseous state. Glyceraldehyde+unionized glycine reaction favors the formation of 2,5-dimethyl pyrazine mainly in the gaseous phase. Glyceraldehyde+protonated glycine and glyceraldehyde+glycine zwitterion reactions are assumed to be less favorable for the formation of 2,5-dimethyl pyrazine. Aminoacetones have been found to be the most likely precursors for the formation of pyrazine rings. Oxidation plays an important role during the formation of 2,5-dimethyl pyrazine. Water plays an important role for the initiation of both of the gaseous and aqueous phase glyceraldehyde+glycine reactions.

Computational studies on glyceraldehyde and glycine Maillard reaction-II

Density functional theory calculations have been performed on the proposed mechanism for the intermediate stage of glyceraldehyde and glycine Maillard reaction under different pH conditions at the standard state. By following the total mass balance, possibility of the formation of different compounds in the proposed mechanism has been tested by estimating the Gibb's free energy changes of the reaction. Electronic energy changes have also been calculated to observe the internal energy changes during the reaction. The result reveals that methyl glyoxal is one of the most likely product in the intermediate stage of the reaction. 3-Deoxyosone route in the intermediate stage is feasible for the production of methyl glyoxal in glyceraldehyde+unprotonated glycine reaction, whereas both of the 3- and 1-deoxyosone routes are feasible in glyceraldehyde+deprotonated glycine reaction. As both of the 3- and 1-deoxyosone routes favor the production of methyl glyoxal, glyceraldehyde+deprotonated glycine reaction is assumed to be more feasible for the nonenzymatic browning than that of the others. Glyceraldehyde+protonated glycine and glyceraldehyde+glycine zwitterion reactions are assumed less favorable for the production of methyl glyoxal. These findings will be helpful for further studies, and finding out proper mechanisms of the reaction.

Computational studies on glyceraldehyde and glycine Maillard reaction—I

Mechanisms for the initial stage of glyceraldehyde and glycine Maillard reaction under different pH conditions have been proposed, following usually the Hodge-scheme. Computations have been performed on the mechanisms at the standard state to test the possibility of the formation of different compounds, through evaluating the changes in Gibb's free energy during the reaction. Electronic energy changes during the reaction have also been evaluated. Glyceraldehyde+deprotonated glycine reaction has been found to be the most favorable for the formation of the Amadori rearrangement products in both gaseous and aqueous states. Due to the possibility of the production of both enol and keto forms of the Amadori rearrangement product, the rate of browning in glyceraldehyde+deprotonated glycine reaction is assumed to be faster than the others. Glyceraldehyde+unionized glycine reaction has been found to be more plausible for the formation of the keto form of the Amadori rearrangement products, particularly, in the gaseous phase. Glyceraldehyde+protonated glycine and glyceraldehyde+glycine zwitterion reactions are not favorable for the formation of the Amadori rearrangement products. Formation of hydroxyacetaldehyde from glyceralaldehyde, as one of the possible C2-fragmentation product, has been found to be favorable in the aqueous state.

Use of GC-headspace and “electronic nose” for the detection of volatile compounds from glucose–glycine Maillard reaction

The present study deals with the use of headspace and gas sensor techniques for the measurements of Maillard volatiles in model system. Both methods can be used for assessing various processes in food control. The volatile compounds produced during thermal browning of glucose–glycine model system were collected by dynamic headspace techniques and analysed by GC–MS. The effect of added formaldehyde on the formation of the main constituents was measured at pH 4.5, 5.5 and 6.5. It was found that at pH 5.5 and 6.5 formaldehyde had a negative effect on the formation of the dominant components, furfural, 2-acetylfuran and 5-methylfurfural. The volatile compounds were also tested with an array of solid-state gas sensors. The effect of formaldehyde and acetaldehyde was analysed on the basis of the transient response signals generated by the aroma in the sensors. So-called τ-patterns were used to recognise the aroma from different model solutions as well as for pure compounds dominant in the aroma from the Maillard reaction.