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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Beer Thiol-Containing Compounds and Redox Stability: Kinetic Study of 1-Hydroxyethyl Radical Scavenging Ability

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de Almeida, Natalia E. C. [1, 2] ; Lund, Marianne N. [1, 3] ; Andersen, Mogens L. [1] ; Cardoso, Daniel R. [2]
Total Authors: 4
[1] Univ Copenhagen, Dept Food Sci, DK-1958 Frederiksberg C - Denmark
[2] Univ Sao Paulo, Inst Quim Sao Carlos, BR-13560970 Sao Carlos, SP - Brazil
[3] Novozymes AS, DK-2880 Bagsvaerd - Denmark
Total Affiliations: 3
Document type: Journal article
Source: Journal of Agricultural and Food Chemistry; v. 61, n. 39, p. 9444-9452, OCT 2 2013.
Web of Science Citations: 14

The 1-hydroxyethyl radical is a central intermediate in oxidative reactions occurring in beer. The reactivity of thiol-containing compounds toward 1-hydroxyethyl radical was evaluated in beer model solutions using a competitive kinetic approach, employing the spin-trap 4-POBN as a probe and by using electron paramagnetic resonance to detect the generated 1-hydroxyethyl/4-POBN spin adduct. Thiol-containing compounds were highly reactive toward the 1-hydroxyethyl radical with apparent second order rate constants close to the diffusion limit in water and ranging from 0.5 x 10(9) L mol(-1) s(-1) for the His-Cys-Lys-Phe-Trp-Trp peptide to 6.1 X 10(9) L mol(-1) s(-1) for the reduced lipid transfer protein 1 (LTP1) isolated from beer. The reactions gave rise to a moderate kinetic isotope effect (k(H)/k(D) = 2.3) suggesting that reduction of the 1-hydroxyethyl radical by thiol-containing compounds takes place by hydrogen atom abstraction from the RSH group rather than electron transfer. The content of reduced thiols in different beers was determined using a previously established method based on ThioGlo-1 as the thiol derivatization reagent and detection of the derivatized thiols by reverse phase liquid chromatography coupled to a fluorescence detector. The total level Of thiol in beer (oxidized and reduced) was determined after a reduction step employing 3,3',3{''}-phosphanetriyltripropanoic acid (TCEP) as the disulfide reductant. A good correlation among total protein and total thiol content in different beers Was observed The results suggest a similar ratio between reduced thiols and disulfides in all of the tested beers, which indicates a similar redox state. (AU)

FAPESP's process: 11/09273-4 - Reactivity of terpenes and prenylflavonoids towards radicals formed during the aging process of beer
Grantee:Natália Ellen Castilho de Almeida
Support Opportunities: Scholarships in Brazil - Doctorate
FAPESP's process: 11/51555-7 - Bread and meat for the future
Grantee:Daniel Rodrigues Cardoso
Support Opportunities: Regular Research Grants
FAPESP's process: 12/03916-3 - Investigation of beer oxidative stability conferred by thiol-containing proteins
Grantee:Natália Ellen Castilho de Almeida
Support Opportunities: Scholarships abroad - Research Internship - Doctorate
FAPESP's process: 09/54040-8 - Acquisition of a high-resolution Orbitrap mass spectrometer for the discovery and structural analysis of biologically active compounds: applications in proteomics, biomarkers, synthesis, isolation, and characterization of natural products, studies of redox systems in food and enzymatic synthesis
Grantee:Emanuel Carrilho
Support Opportunities: Multi-user Equipment Program