Malt flavour--transformation of carbonyl compounds by yeast during fermentation

Laboratory and pilot scale fermentations have been carried out using worts spiked with a range of carbonyl compounds, many of which are derived from malt. Aldehydes and vinyl ketones were chemically reduced during fermentation and could not be detected in the resulting beers; on the other hand certain saturated and non‐conjugated unsaturated ketones were only partially reduced. The corresponding saturated alcohols and acetate esters were usually detected as transformation products.