Mechanism of pyrazole formation in [13C-2] labeled glycine model systems: N–N bond formation during Maillard reaction

Yaylayan, Varoujan A.; Haffenden, Luke J.W.

doi:10.1016/s0963-9969(03)00003-6

Cited by 12 publications

(7 citation statements)

References 11 publications

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“…The majority of studies consider MR as a series of subsequent and parallel reactions. Although pyrazoles are not considered common MRPs, their presence was evidenced in Maillard systems, indicating the diversity of molecular structures that could be formed during the reaction (Yaylayan and Haffenden, 2003). In order to test the hypothesis that the pyrazoles obtained here could be MRPs, a mixture consisting of L-tryptophan and sucrose in water (in the same proportion as that used for the MS media) was processed in the same way as calli (50 o C, 24 h), extracted, and injected in HPLC.…”

Section: Resultsmentioning

confidence: 99%

Search for alkaloids on callus culture of Passiflora alata

Machado

Neto

Salgado

et al. 2010

Braz. arch. biol. technol.

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Preliminary work on Passiflora alata leaves failed to detect harmane alkaloids using LC. The aim of this work was to investigate the production of harmane alkaloids through the cell culture of P. alata, inducing its precursor (Ltryptophan). The leaf explants presented satisfactory results after disinfection, and the callus formation was initiated in MS media with adequate quantities of phytohormones. Sixty days after inoculation, calli were inoculated in the optimized semi-solid MS media, with and without the addition of L-tryptophan (50, 100, 200 mg/L)

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Section: Resultsmentioning

confidence: 99%

Search for alkaloids on callus culture of Passiflora alata

Machado

Neto

Salgado

et al. 2010

Braz. arch. biol. technol.

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“…To demonstrate the utility of oxidative pyrolysis technique we have utilized a previously identified6 oxidative formation of 3,4,5‐trimethylpyrazole from 3‐hydroxy‐2‐butanone/glycine mixture as a test model to perform oxidative and nonoxidative pyrolysis and compare the intensities of 3,4,5‐trimethylpyrazole peaks (an important contributor to the aroma of the alcoholic beverage tequila). The proposed mechanism, shown in Figure 8, has been verified through labeling studies6 and involves oxidative N‐N bond formation similar to disulfide bonds. The data have indicated a 60‐fold increase in the formation of the pyrazole under oxidative pyrolysis.…”

Section: Resultsmentioning

confidence: 99%

“…The significance of the proposed redox cycle lies in the fact that the reactive primary amino group in structure 3 allows dimerization and other reactions with different aldehydes or ketones to form neutral and stable N‐containing heterocyclic aroma compounds such as pyrazines, pyrroles, and oxazoles,6,10‐12 whereas the secondary amino group in structure 4 prevents such amino‐carbonyl‐type reactions to proceed to the extent of formation of stable aromatic moieties; for example, in the case of dimerization, it leads to the formation of N,N′‐dialkyl‐dihydropyrazines that are unable to aromatize and eventually form, through a single electron transfer process, very unstable pyrazinium radical cations 13. Being unstable, these cations undergo further disproportionation13 to regenerate dihydropyrazine and form doubly charged pyrazinium diquaternary salts considered to be the precursors of colored melanoidins.…”

Section: Resultsmentioning

confidence: 99%

Oxidative Pyrolysis and Postpyrolytic Derivatization Techniques for the Total Analysis of Maillard Model Systems: Investigation of Control Parameters of Maillard Reaction Pathways

Yaylayan

Haffenden

Chu

et al. 2005

Annals of the New York Academy of Sciences

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Factors that regulate various pathways of Maillard reaction leading to aroma, color, or carcinogen generation have not been identified, due to the difficulties associated with analyzing complex reaction mixtures. In particular, the role played by oxidation in directing aromagenic, chromogenic, or carcinogenic pathways is not well understood. In order to overcome the analytical difficulties, novel Py-GC/MS-based methodologies were developed to analyze volatile and nonvolatile residues of Maillard reaction products generated from the same model system under air or helium atmosphere. The analysis of nonvolatiles was achieved through a postpyrolytic in situ derivatization technique using hexamethyldisilazane, and pyrolysis under air was achieved through modification of the GC equipped with sample concentration trap to allow gas stream switching and subsequent isolation of the pyrolysis chamber from the analytical stream. In this approach label incorporation from the starting materials can be observed in both volatile and nonoxidative conditions for mechanistic studies. In addition, monitoring of redox potentials, oxygen consumption, and color generation of relevant model systems over time were also carried out at different temperatures. The data collected have indicated that perturbation in the redox potential of Maillard model systems by external (oxidizing conditions) or internal (formation of reductones) factors can alter the balance among the four critically important groups of precursors: alpha-dicarbonyl, alpha-hydroxycarbonyl, 2-aminocarbonyls, and 2-(amino acid)-carbonyl compounds and hence control the relative importance of aromagenic versus chromogenic pathways.

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“…The Maillard reaction involves the reaction of the carbonyl group of reducing sugar with an amino compound, which cyclizes to the N‐substituted glycosylamine and forms an Amadori rearrangement product (ARP). Further reactions give rise to the formation of different intermediate products including reductones, pyrazine and a variety of other cyclic substances . Large quantities of the intermediate product 5‐hydroxymethyl‐2‐furaldehyde (HMF) are formed in certain foods .…”

Section: Introductionmentioning

confidence: 99%