125th Anniversary Review: The Non-Biological Instability of Beer

Abstract

Unlike many alcoholic beverages beer is inherently unstable. In chemical (as opposed to microbiological) terms this instability can be considered -and is here reviewed -in the categories of colloidal instability, foam, gushing, flavour instability and light sensitivity

A Comparative Analysis of Different Pitching Rates on Castle Lager Beer Flavour Stability: A Case Study of Delta Lagers Manufacturing Company Harare, Zimbabwe

“…This was because there were high levels of SO 2 produced during fermentation in beer pitched with a lower rate and it acted as an antioxidant. SO 2 has three main roles in beer, firstly it reacts with carbonyl compounds to form alpha-hydroxysulphonates and these are not flavour active and thus increase the threshold of carbonyl compounds responsible for the stale flavour (Bamforth, 2011). Also sulphur dioxide inhibits oxidative reactions.…”

“…Figure 4 illustrates the flavour wheel of the sample with pitching rate of 0.7kg/hl which has flavour defects such as papery which is due to the oxidation. According to Bamforth [4] it can be said that all beers are susceptible to flavour degradation due to aging. Thus flavour active compounds such as furfural, trans-2-nonenal, acetaldehyde and other oxidative products of normal beer flavour constituents are responsible for contributing cardboard, papery or strawberry like off flavours to beer.…”

“…There are numerous sulphur containing compounds in finished beer [4] , the factors that contribute to sulphur notes are poor kettle boil, low oxygenation of the wort, yeast strain, slow fermentation, bacterial contamination and exposure of bottle beer to light . As illustrated by figure 11, beer fermented with a pitching rate of 0.9kg/hl almost had the same flavour defects .…”

“…Appearance and taste (colour, hue, brightness, foam quality, glass fullness and flavor) are the sensory attributes on which consumers judge the acceptability of the product and they use them to critically evaluate every glass of beer they drink. The major thrust in beer quality lies upon the beers' foam stability, colloidal stability and most importantly flavour stability [4]. Beer flavour stability is of paramount importance since it has the potential to detrimentally affect foam and colloidal stability.…”

The Production of Secondary Metabolites with Flavour Potential during Brewing and Distilling Wort Fermentations

“…Over 200 carbonyl compounds are reported to contribute to the flavour of fresh beer and other alcoholic beverages [1,6]. These compounds influence beer flavour and are produced as a result of yeast metabolism during fermentation.…”