SENSORY QUANTIFICATION OF BITTERNESS AND FLAVOUR OF BEER DURING STORAGE*

Sensory techniques were utilized to measure bitterness and degree of liking for commercial lagers, and to quantify aroma and flavour qualities of two sets of experimental lagers. Significant negative correlations were obtained between sensory bitterness and degree of liking for 17 commercial beers, by inexperienced as well as by trained judges. Sensory bitterness was positively correlated with BU values, with both measurements negatively correlated with beer age. In experimental lagers, BU values decreased with increasing time and temperature of storage, but sensory bitterness, as determined by trained judges, decreased only with storage time. Increases in malty, ethanol, and skunky aromas with time of storage were accompanied by decreases in hoppy, musty, and wet cardboard aromas. Baked aroma increased sharply with increasing storage temperature. In a second set of experimental lagers varying in pH (3·7, 4·2, or 4·6) and/or headspace gas, sourness was markedly affected by pH whereas baked flavour was significantly stronger in beers with O₂ than in those with CO₂ headspace. The data are discussed in terms of differences between analytical and consumer-type sensory testing, and in terms of changes in aroma and flavour attributable to iso-α-acid content, pH, headspace gas, and time and temperature of storage.