Characterisation of stable radical from dark roasted malt in wort and beer

TY - JOUR

T1 - Characterisation of stable radical from dark roasted malt in wort and beer

AU - Jehle, Doris

AU - Lametsch, Marianne Lund

AU - Øgendal, Lars Holm

AU - Andersen, Mogens Larsen

PY - 2011/3/15

Y1 - 2011/3/15

N2 - An exceptionally stable radical was detected by electron spin resonance (ESR) spectroscopy at room temperature directly in dark beers and in sweet wort produced with dark malt. The ESR spectrum was a broad singlet signal without any hyperfine structure and a g-value of 2.0040. The radical was detected at the initial step of the mashing process and the radical intensity increased with higher proportions of dark malt suggesting a water-soluble radical complex that is formed during the roasting of malt. The radical was further characterised by several precipitation protocols suggesting a melanoidin-derived radical. Size-exclusion chromatography and light scattering measurements showed that the radical was associated with a high molecular weight complex of approximately 106-108g/mol. The radical proved to be stable towards Fenton reactants, freezing or heating temperatures. Radical intensity was shown to be stable in the presence of oxygen and decreased reversibly under a nitrogen atmosphere.

AB - An exceptionally stable radical was detected by electron spin resonance (ESR) spectroscopy at room temperature directly in dark beers and in sweet wort produced with dark malt. The ESR spectrum was a broad singlet signal without any hyperfine structure and a g-value of 2.0040. The radical was detected at the initial step of the mashing process and the radical intensity increased with higher proportions of dark malt suggesting a water-soluble radical complex that is formed during the roasting of malt. The radical was further characterised by several precipitation protocols suggesting a melanoidin-derived radical. Size-exclusion chromatography and light scattering measurements showed that the radical was associated with a high molecular weight complex of approximately 106-108g/mol. The radical proved to be stable towards Fenton reactants, freezing or heating temperatures. Radical intensity was shown to be stable in the presence of oxygen and decreased reversibly under a nitrogen atmosphere.

U2 - 10.1016/j.foodchem.2010.09.011

DO - 10.1016/j.foodchem.2010.09.011

M3 - Journal article

SN - 0308-8146

VL - 125

SP - 380

EP - 387

JO - Food Chemistry

JF - Food Chemistry

IS - 2

ER -