Quality of pilsner malt and roasted malt during storage

TY - JOUR

T1 - Quality of pilsner malt and roasted malt during storage

AU - Hoff, Signe

AU - Lametsch, Marianne Lund

AU - Petersen, Mikael Agerlin

AU - Jespersen, Birthe P Møller

AU - Andersen, Mogens Larsen

PY - 2014

Y1 - 2014

N2 - Malt is usually expected to be stable during 12months of storage. However, in practice many brewers notice changes in malt aroma during storage. The oxidative stabilities of pilsner malt and roasted malt were evaluated during a 12month storage at different temperatures (10 and 20°C) and water activities (0.231 and 0.432). The radical content in malt kernels was measured by electron spin resonance spectroscopy and the volatile profile of the resulting sweet worts was measured by head-space analysis followed by GC-MS analysis. The storage of malt resulted in oxidative reactions and a large change of the volatile profile of the resulting worts. Roasted malt was much more unstable than pilsner malt, as illustrated by a higher initial radical intensity, larger radical decay during storage and a larger change in the volatile profile of the wort with increased amounts of lipid oxidation products. For both roasted malt and pilsner malt, good correlations were found between radical decay and changes in the volatile profile of the wort, where high temperature and high water activity resulted in the largest changes. During the 12months of storage, the sugar extract of the wort made from the malts remained constant and was not affected by the chemical changes. This study suggests that chemical changes occurring in malts during less than 12months of storage may potentially affect the aroma of beer, and that water activity and storage temperature should both be kept low in order to maintain a high malt quality.

AB - Malt is usually expected to be stable during 12months of storage. However, in practice many brewers notice changes in malt aroma during storage. The oxidative stabilities of pilsner malt and roasted malt were evaluated during a 12month storage at different temperatures (10 and 20°C) and water activities (0.231 and 0.432). The radical content in malt kernels was measured by electron spin resonance spectroscopy and the volatile profile of the resulting sweet worts was measured by head-space analysis followed by GC-MS analysis. The storage of malt resulted in oxidative reactions and a large change of the volatile profile of the resulting worts. Roasted malt was much more unstable than pilsner malt, as illustrated by a higher initial radical intensity, larger radical decay during storage and a larger change in the volatile profile of the wort with increased amounts of lipid oxidation products. For both roasted malt and pilsner malt, good correlations were found between radical decay and changes in the volatile profile of the wort, where high temperature and high water activity resulted in the largest changes. During the 12months of storage, the sugar extract of the wort made from the malts remained constant and was not affected by the chemical changes. This study suggests that chemical changes occurring in malts during less than 12months of storage may potentially affect the aroma of beer, and that water activity and storage temperature should both be kept low in order to maintain a high malt quality.

U2 - 10.1002/jib.144

DO - 10.1002/jib.144

M3 - Journal article

SN - 0046-9750

VL - 120

SP - 331

EP - 340

JO - Journal of the Institute of Brewing

JF - Journal of the Institute of Brewing

IS - 4

ER -