The Contribution of Oxidation Reactions to Non-enzymatic Browning

Dear Colleagues,

Due to its heterogenous and non-selective nature, color formation in non-enzymatic browning reactions is not comprehensively understood. In this regard, oxidation in the presence of molecular oxygen, which is catalyzed in the presence of transition metals or under alkaline conditions, plays a vital role in the formation of precursor molecules, most prominently sugar- and lipid-derived 1,2-dicarbonyl compounds, but also ortho-quinones of phenolic compounds. Although addition reactions of C-H-acidic carbonyl compounds, amines, or even thiols are considered to contribute to the formation of complex colorants, known as melanoidins (the ‘Maillard reaction’) and melanins, such simple addition reactions do not result in the formation of chromophore systems. Apart from simple condensation, the oxidation of these products is a widely accepted reaction pathway, occurring during polymerization, which enables the formation of sufficiently large conjugated π-electron systems that are required for these compounds to exhibit a meaningful brown color intensity.

This Special Issue of Oxygen aims at bringing together the latest knowledge, ideas, considerations, and overviews on non-enzymatically induced oxidation reactions of compounds that contribute to the formation of colored products. We highly appreciate contributions of original research and review articles related to the non-enzymatic browning of primarily carbohydrates, lipids, and phenolic compounds that might be induced or accelerated by redox-active species or even molecular oxygen.

Prof. Dr. Sascha Rohn
Dr. Clemens Kanzler
Guest Editors

Leon Valentin Bork
Guest Editor Assistant

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Oxygen is an international peer-reviewed open access quarterly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1000 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

• color formation
• non-enzymatic browning
• oxidation
• quinones
• carbonyl compounds
• phenolic compounds
• melanoidins
• melanins