Hopping Technology in Relation to Beer Bitterness Consistency and Flavor Stability

et al. 2010

Self Cite

Analytical and sensory aspects of hoppy aroma of conventionally hopped and advanced hopped pilot Pilsner beers were investigated. Linalool and several sesquiterpenoids were used as analytical markers for the hoppy aroma of the beers. Levels of linalool and sesquiterpenoids in the fresh beers, as well as sensory characteristics of hoppy aroma (intensity and attributed aroma descriptor(s)) clearly depended on the applied hop aromatisation technology and on the type of hop oil fraction used in advanced hopping. The most pronounced hoppy aroma was observed for the advanced bittered beers, either aromatised post‐fermentation using a polar hop essence or at the end of wort boiling using pellets (late‐hopping). However, all refined hop oil fractions used in this study for advanced aromatisation clearly affected the hoppy aroma impression. Analytical data on staling indicators, combined with sensory evaluations, further suggest that hop oil preparations may also affect flavour stability of the resulting beers in a positive way. In general, it can be concluded that hop aromatisation, whether performed in the advanced or conventional way, appears to mask beer staling, as demonstrated by lower overall sensory ageing scores.

Section: Con-pel (µG/l)supporting

confidence: 90%

Analytical and Sensory Assessment of Hoppy Aroma and Bitterness of Conventionally Hopped and Advanced Hopped Pilsner Beers

Opstaele

Rouck

et al. 2010

Self Cite

“…2. As reported in several studies 8,18,30,31,33,59 , significant degradation of iso-α-acids occurs during beer ageing, due to oxidative deterioration. After ageing for 60 days at 30°C, the remaining relative concentration of iso-α-acids in the beers is comparable.…”

Section: Evaluation Of Bitterness Profilesmentioning

confidence: 71%

“…Moreover, besides formation of staling volatile aldehyde compounds, a lot of other unwanted reactions e.g. oxidation of beer bitter acids 5,[17][18][19]31 and oxidation and polymerisation of malt and hop polyphenols 41 , also occur during beer storage.…”

Section: Introductionmentioning

confidence: 99%

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

Malfliet

Opstaele

et al. 2008

Self Cite

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.

“…Upon storage in the absence of light, these compounds rapidly undergo degradation in the presence of oxygen species 18,24,32 . This oxidative degradation of iso-α-acids results in a significant decline in beer bitterness intensity and a quality change towards a lingering, more harsh bitterness, accompanied by an astringent note in the taste 10,22,27,28,36 , and has been linked to the development of volatile carbonyl compounds such as 2-methylpropanal, 2-methylbutanal and 3-methylbutanal, associated with staling of beer flavour 4,17,18,33,51 .…”

Section: Introductionmentioning

confidence: 99%

“…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

Rouck

Cooman

et al. 2010

Self Cite

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.