Iso-␣-acids and their chemically modified variants play a large role in evoking the bitter sensory attributes of lager character, but individual consumers may vary in their perception of bitterness. Sixteen lagers were scored in rank-rating for bitterness by 14 trained assessors and the concentrations of the six bitter components in these beers were determined by high performance liquid chromatography. Relationships between bitterness intensity and the bitter components were modelled well using partial least square regression with a correlation value of 0.92. When 8 assessors carried out time-intensity scoring of bitterness, profiles for single products were very different. However, single assessor profiles for multiple products showed qualitative similarities but quantitative differences. That individual assessors perceived bitter characters differently in relation to time has implications for new product development.

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Lager is generally brewed to minimise the final sugar content but despite this can have sweet characters. Such flavour notes have been ascribed to concentrations above flavour thresholds of certain volatile congeners: maltol; 4-hydroxy-2,5-dimethyl-3(2H)-furanone (HDMF); 4-hydroxy-2(5)-ethyl-5(2)-methyl-3(2H)-furanone (HEMF); hydroxymethylfurfural (HMF); diacetyl; and specific esters (ethyl acetate, ethyl caproate, ethyl caprylate, and iso amyl acetate). Relationships between scoring of sweetness in lagers and quantitative data on relevant congeners and ethanol were explored. Lagers (23) were scored for sweetness using rank rating and in 18 lagers ten relevant volatile congeners were quantified by gas chromatography. Relationships between sensory and compositional data were modelled. Multiple linear regression was less successful than partial least squares regression (PLS1) based on four principal factors. Calibration values for r 2 were 0.70 and 0.77, when ester data was excluded and included, and validation values were 0.56 and 0.45, respectively. Prediction was improved to a validation r 2 = 0.74 when an artificial neural network was used in modelling with the complete compositional data set. It was concluded that in lagers a range of congeners and ethanol contribute in a complex manner to perceptions of sweetness and the relationship with 4-hydroxyfuranone derivatives merits revaluation.

Lagers are generally brewed to minimise the final sugar content. Residual saccharides, derived from starch, contribute little to sweetness. Despite this, certain lagers exhibit sweet characters. These have not been explored in lagers, but are thought to originate from: maltol; 4-hydroxy-2,5-dimethyl-3(2H)-furanone (HDMF); 4-hydroxy-2(or 5)-ethyl-5(or 2)-methyl-3(2H)-furanone (HEMF); hydroxymethylfurfural (HMF); diacetyl; and certain esters (ethyl acetate, ethyl caproate, ethyl caprylate, and iso amyl acetate). This study used time-intensity (TI) profiling, employing 13 assessors, to study sweetness in 10 lagers, scored similarly for sweetness in rank rating. Single intensity maxima were obtained with all products and all assessors. Data were analysed using ANOVA of curve parameters and non-centred and centred principal component analyses (PCA). In ANOVA only the area under curve (A tot ) values differed significantly. However, shape of TI profile, or signature, differed between assessors who could on this basis be divided into two groups. In the multivariate data analyses, non-centred PCA showed significant differences between lagers, parametric modelling and conventional PCA did not. However TI profile data suggested sweetness intensity perceived over the 120 seconds following ingestion could differ, although differences in scoring in rank rating were not significant.

Key compounds in lager staling include furfural, hexanal, 5-hydroxymethyl furfural (5-HMF), and trans-2-nonenal. Quantitative data of headspace concentration in two lagers -one premium at 5% (abv), the other a standard product at 4% (abv) -were obtained by solid phase microextraction (SPME) followed by gas chromatography using a mass selective detector (GCMS). The concentrations of the aldehydes were used to predict overall stale scoring from sensory assessor data, of lagers stored at 4, 12, 30, and 37°C for 7, 14, 21 and 28 days. Concentrations of all four aldehydes increased with time of storage and with higher temperatures. Correlation coefficients for prediction of staleness in the premium lager were similar at 0.81 and 0.84 for partial least square regression (PLS1) and artificial neural network (ANN) modelling respectively, and the latter showed a lower root mean square error (RMS error). For the standard product, the correlation coefficients were 0.72 and 0.86, with ANN showing lower RMS error respectively. In both PLS models, E-2-nonenal had high regression coefficients and 5-HMF lower coefficients. Furfural and hexanal differed in contributions to the lagers.