posted on 2018-09-10, 00:00authored byMatthias Baldus, Sarah Majetschak, Daniel Hass, Raphael Klein, Thomas Kunz, Marta Saba Kunicka, Frank-Jürgen Methner
During malt kilning, dimethyl sulfide
(DMS) is partly oxidized
to dimethyl sulfoxide (DMSO), which can be reduced by yeast to generate
DMS during fermentation. The aim of this study was to test the effect
of malt-derived potential antioxidants on DMS oxidation and to assess
their applicability for DMSO minimization. In the presence of 18 μM
copper, all tested antioxidants (250 μM) catalyzed DMS oxidation
to deviating extents (sulfite > ascorbic acid (Asco) > gallic
acid
(GA) > L-cysteine (Cys) > L-glutathione (GSH)).
Hydrogen peroxide was found as primary DMS oxidant for each substance
except for sulfite. Electron spin resonance spectroscopy provided
evidence for the formation of bisulfite radicals and peroxymonosulfate
radicals, which are proposed as being capable of exhaustive DMS oxidation
(∼100%) over a wide concentration. The data demonstrate that
use of antioxidants per se cannot be suggested for the minimization
of DMSO formation in malt and other foodstuffs. Potential shifts from
pro- to antioxidative behavior of antioxidants and their implications
on malt quality are discussed.