A New Parameter for Determination of the Extent of Staling in Beer

125

Flavour changes of six Belgian pale lager beers were studied in order to estimate the importance of different parameters and reactions in relation to the ageing process. An attempt was made to link analytical data with sensory evaluation using multivariate statistical analysis. Partial least squares regression techniques (PLSR) were employed on the analytical and sensory data. As apparent from the PLSR model, significant indicators of lager beer ageing are aldehyde markers (especially total aldehydes, furfural, hexanal, 2-methylpropanal, 2-methylbutanal, and 3-methylbutanal), cold and permanent haze, and beer colour. Conversely, compounds or parameters that load negatively in the PLSR model for beer ageing are trans-isohumulones, cis-isohumulones, total bitterness, the T/C-ratio, polyphenolic markers (especially proanthocyanidins), the flavanoid content, and, to a lesser extent, the TB-index and reducing power (TRAP). The integrated analytical-sensorial methodology is proposed as a useful tool for evaluation of the flavour instability of pale lager beers.

Section: Introductionmentioning

confidence: 99%

Flavour Instability of Pale Lager Beers: Determination of Analytical Markers in Relation to Sensory Ageing

Malfliet

Opstaele

Clippeleer

et al. 2008

125

“…On the other hand, the oxidative decomposition of iso-α-acids during beer ageing has also been linked to the formation of a series of nonvolatile trans-specific cyclic iso-α-acid transformation products, exhibiting the aforementioned harsh lingering bitter taste 22,27,28 . Indeed, various researchers have independently revealed that trans-iso-α-acids degrade much faster than their cis-counterparts, the latter remaining largely unaltered even after prolonged storage 2,9,10,11,22,24,32,36,52 .…”

Section: Introductionmentioning

confidence: 99%

Influence of the Hopping Technology on the Storage-induced Appearance of Staling Aldehydes in Beer

Clippeleer

Rouck

Cooman

et al. 2010

In this paper, the involvement of iso-α-acids in the appearance of stale flavour in beer during storage was examined. Flavour instability upon storage, by far the most important quality problem of beer, may be caused by a multitude of reactions, in particular, the degradation of trans-iso-α-acids is pivotal. In order to gain improved understanding of the beer ageing process, the behaviour of the stereoisomers of the bitter acids was studied for the first time in pilot beers at particularly high and low proportions of the trans-iso-α-acids concentration relative to the cis-iso-α-acids concentration. Therefore, pure trans-respectively cis-isomers were required and obtained on a pilot scale by the separation of trans-iso-α-acids as β-cyclodextrin inclusion complexes from a commercial isomerised hop extract, permitting the quantitative dosage to beer in mg/L amounts. The relationship between the storage-induced degradation of these iso-α-acids in authentic beer samples and the increase in staling aldehydes, especially 2-methylpropanal, 2-methylbutanal and 3-methylbutanal, is the subject of further investigations. A remarkable increase in the relative concentration of cis-iso-α-acids was observed in the beers bittered with purified trans-iso-α-acids, which may be ascribed to partial conversion, i.e., reverse isomerisation, of trans-iso-α-acids via α-acids into cis-iso-α-acids. In spite of the trans-specific degradation observed during ageing, the decomposition of these bitter acids leading to volatile carbonyl compounds is of minor importance. Aldehyde formation as a function of forced ageing was irrespective of the mode of bittering, emphasising that malt quality and the brewing process itself are probably the most important factors regarding the flavour instability of beer.

“…Lagers differ in character as a consequence of process and recipe differences. During storage, canned lager flavour changes depending upon product factors such as pH 9,15 , initial wort composition, pitching rate and yeast strain 15 , post-fermentation processing, subsequent storage time and temperature 1,15 , and the concentration of oxygen in the can.…”

Section: Introductionmentioning

confidence: 99%

“…In 1998, cans constituted 24% of total UK beer sales 2 with a typical shelf life of 9 months at ambient temperature. The storage temperature of canned and bottled lagers, particularly at over 30°C 7,8,16,18 , impacts heavily on flavour development particularly with respect to carbonyl compounds such as aldehydes 1,2,6 .…”

Section: Introductionmentioning

confidence: 99%

Staling in Two Canned Lager Beers Stored at Different Temperatures - Sensory Analyses and Consumer Ranking

Techakriengkrai

Paterson

Taidi³

et al. 2006

Two canned lagers, lager A (5% abv with late hop character) and lager B (4% abv) stored for 0, 7, 14, 21 and 28 days at 4, 12, 30 and 37°C were scored by trained sensory assessors (10) for liking and stale and related attributes of : cabbagy, cardboard, catty, grainy, honey, leathery, metallic, musty, skunky, and sour. Principal component analysis explained 80% data variance in 3 significant (p < 0.05) and 75% in 4 significant factors for A and B, respectively. In both lagers, aging correlated significantly with stale, cabbagy and musty and in A with metallic and sour and in B with catty and skunky. Partial least squares regression (PLS1) models showed good explanations: stale had regression coefficients of 0.88 (calibration) and 0.84 (validation) for A, and 0.96 and 0.91 respectively, for B; for liking 0.92 and 0.90 for A and 0.96 and 0.93 for B. For both lagers, liking was positively correlated with honey and grainy, and inversely with staling attributes. Lagers from 30°C were ranked for liking by 40 consumers against fresh as a hidden reference. Significant (p = 0.05) ranking of A, but not B, correlated with that of trained assessors.