Improvement of the Oxidative Wort and Beer Stability by Increased Unmalted Barley Proportion

The influence of unmalted barley on the brewing process and the quality of the resulting beer-like beverages was investigated with the main focus on the oxidative stability by using traditional beer analyses and EPR-Spectroscopy (EAP-, T₄₅₀-value). Although all analytical values of the final beverages were within the normal range according to MEBAK, a slight decrease in total polyphenol and FAN content caused by an increased barley proportion in the grist was measured. In direct correlation an increase of higher molecular proteins and ß-glucan were detectable. The missing heat exposure and oxidative stress by the malting process resulted in lower values of TBI and wort respectively beer colour with increasing barley proportions in the grist..

Based on these results, it can be said that beers with a barley proportion up to 75 % will achieve comparable or higher final attenuation of the “beer” due to a combined effectiveness of malt and technical enzymes. Furthermore, it was observable that an increase of barley content leads to higher oxidative stability (EAP-value) and a lower EPR signal intensity (T₄₅₀-value) as an indicator for the radical generation in the wort and final beverage. In comparison to beer produced with 100 % of malt, the beers brewed with up to 50 % barley proportion were slightly preferred and up to 75 % comparable in sensory analyses. Only the brew with a barley proportion of 90 % showed a more astringent bitter taste.

BrewingScience - Monatsschrift für Brauwissenschaft, 64 (July/August 2011), pp. 75-82