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Mechanistic aspect of 3-methyl-2-butene-1-thiol formation in beer

Grant number: 07/06199-2
Support type:Scholarships in Brazil - Master
Effective date (Start): August 01, 2008
Effective date (End): February 28, 2010
Field of knowledge:Agronomical Sciences - Food Science and Technology
Principal Investigator:Daniel Rodrigues Cardoso
Grantee:Gustavo Tokoro Riether
Home Institution: Instituto de Química de São Carlos (IQSC). Universidade de São Paulo (USP). São Carlos , SP, Brazil


The current increase of competitivity in the different agro-industrial chain, as much for domestic market and the international as well, has forced producers and industries to develop better quality products in the ambit of the food safety, rastreability, and sensory properties.Since the primeval until nowadays, the brewing industry is penalized to face problems regarding the product exposition to the light irradiation. The photodegration of beer, a process which yield the formation of 3-methyl-2-but-ene-1-thiol, is considered the key factor that lead to the product rejection by consumers. Up to now, there is no methodology totally efficient that guides to a complete protection of the product from its degradation in light exposing conditions. Although, there is today a deeply knowledge on the mechanism at molecular level of the first steps of the riboflavin photosensitized degradation of isohumulones present in beer, there is still doubts on the role of well know quenchers of riboflavin triplet excited state which are present in considerable amount in beer. Recent data published indicate that the current mechanistic proposal of isohumulones degradation sensitized by riboflavin is kinetically unfavorable under normal beer conditions in view of the quencher’s presence.In view of the need of knowledge on the interaction among these quenchers of riboflavin triplet excited state and transient species formed in the early reaction steps, the present project come across for a contribution to a better knowledge of the role of these transient species in the isohumulones photodegradation and their function as a antioxidant and pro-oxidant agents.In sight of this, it will be carried out reactivity studies of the phenoxyl and the riboflavin radical toward isohumulones by the time resolved electron paramagnetic resonance. Furthermore, it will be carried out photoproduct studies by steady state photolysis and chromatographic analysis coupled to mass spectrometry.

Academic Publications
(References retrieved automatically from State of São Paulo Research Institutions)
RIETHER, Gustavo Tokoro. Aspectos do mecanismo de formação 3-metil-2-buteno-1-tiol em cerveja e a reatividade dos iso-α-ácidos. 2010. Master's Dissertation - Universidade de São Paulo (USP). Instituto de Química de São Carlos São Carlos.

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