Flavor Contribution of Esters in Lager Beers and an Analysis of Their Flavor Thresholds

Headspace solid-phase microextraction and gas chromatography olfactometry mass spectrometry were used to study the effect of 20 volatile esters on the flavor and aroma of a lager beer. Although the content of some esters is low, their contribution to the flavor of beer is prominent, which is closely related to the threshold value. In this study, the threshold values of ethyl octanoate, ethyl butyrate, isobutyl acetate, phenylethyl acetate, ethyl benzoate, and ethyl 3-phenylpropionate were determined following the ASTM E679 standard analysis method for the following amounts of one commercial lager beer from Peking, China: 0.14, 0.67, 1.29, 0.15, and 0.14 mg/L, respectively. In the sensory evaluation, we found that the esters having great contributions for beer taste and flavor harmony (from highest to lowest) were ethyl octanoate, isobutyl acetate, and phenylethyl acetate. According to the results of sensory evaluation, the highest score (7 points) was achieved when the concentration of ethyl octanoate was 0.26 mg/L and the concentration of isobutyl acetate was 1.53 mg/L, which meant that the lager beer flavor and aroma was more harmonious.