Stable radical content and anti-radical activity of roasted Arabica coffee: from in-tact bean to coffee brew.

The roasting of coffee beans generates stable radicals within melanoidins produced by non-enzymatic browning. Roasting coffee beans has further been suggested to increase the antioxidant (AO) capacity of coffee brews. Herein, we have characterized the radical content and AO capacity of brews prepared from Coffea arabica beans sourced directly from an industrial roasting plant. In-tact beans exhibited electron paramagnetic resonance signals arising from Fe3+, Mn2+ and at least three distinct stable radicals as a function of roasting time, whose intensity changed upon grinding and ageing. In coffee brews, the roasting-induced radicals were harboured within the high molecular weight (> 3 kD) melanoidin-containing fraction at a concentration of 15 nM and was associated with aromatic groups within the melanoidins. The low molecular weight (< 3 kD) fraction exhibited the highest AO capacity using DPPH as an oxidant. The AO activity was not mediated by the stable radicals or by metal complexes within the brew. While other non-AO functions of the roasting-induced radical and metal complexes may be possible in vivo, we confirm that the in vitro antiradical activity of brewed coffee is dominated by low molecular weight phenolic compounds.

EPR, free radicals, wine, and the industry: some achievements.

The achievements and uses of electron paramagnetic resonance in the wine industry are pointed out. For example, it first detected stable free radicals in red and white wines and showed that the radical concentration, and therefore the antioxidant action, of white wines was increased by skin and oak exposure. It is expected that EPR will be used more in the future.

Red wines good, white wines bad?

A review of the literature on the 'antioxidant' action of white wines on the cardiovascular system is given. The conclusion is that ingestion only of white wines very low, or lacking, in polyphenolics leads to a reduction in the antioxidant action of blood serum, and to an increase in the low density lipoprotein to high density lipoprotein ratio.