Use of Chemical Indicators of Beer Aging for Ex-post Checking of Storage Conditions and Prediction of the Sensory Stability of Beer

Abstract

The rate of beer aging is affected by storage conditions including largely time and temperature. Although bottled beer is commonly stored for up to 1 year, sensorial damage of it is quite frequent. Therefore, a method for retrospective determination of temperature of stored beer was developed. The method is based on the determination of selected carbonyl compounds called as "aging indicators", which are formed during beer aging. The aging indicators were determined using GC-MS after precolumn derivatization with O-(2,3,4,5,6-pentaflourobenzyl)hydroxylamine hydrochloride, and their profile was correlated with the development of old flavor evolving under defined conditions (temperature, time) using both a mathematical and statistical apparatus. Three approaches, including calculation from regression graph, multiple linear regression, and neural networks, were employed. The ultimate uncertainty of the method ranged from 3.0 to 11.0 °C depending on the approach used. Furthermore, the assay was extended to include prediction of beer tendency to sensory aging from freshly bottled beer.

Insights into chemical and sensorial aspects to understand and manage beer aging using chemometrics

“…Instead, their effect is associated with the beer drinkability (as in changes in mouthfeel and taste) (Baert et al, 2012). Indeed, Cějka et al (2013) found that FA gives a reliable estimation of heat shock and aging of a beer as it correlated well with flavor-active aging compounds, such as the Strecker aldehydes 2-methylbutanal, 3-methylbutanal, phenylacetaldehyde, and 3-methylpropanal. Furthermore, Vrzal, Štěrba, Jurková, and Olšovská (2019) found that the concentration of 5-HMF and FA highly correlates (R 2 = 0.96) with the staling perception in beer.…”

“…Finding suitable molecule indicators for beer aging can be a complicated task. For being a time-consuming activity, many studies determining staling compounds in beer rely on forced aging methodologies rather than natural aging (Bravo et al, 2008;Cějka et al, 2013;Rakete et al, 2014;Saison et al, 2009Saison et al, , 2010Saison, Schutter, Delvaux, & Delvaux, 2008). Nevertheless, the application of forced aging in the determination of staling compounds in beer has been questioned, mainly due to the difference in the final chemical profile between forced and naturally aged beer.…”

“…Indeed, studies have found that within the same beer style the final chemical profile of an aged beer is highly dependent on aging conditions (Saison et al, 2010). However, evidence points toward the valid prediction of aging compounds from studies comparing forcedaged to long-stored naturally aged beer (Cějka et al, 2013;Saison et al, 2009Saison et al, , 2010. Cějka et al (2013), for example, found that aging pale lagers at 45 • C for 6 days was equivalent to aging for 6 months at 20 • C. Therefore, it is worth pointing out that care should be taken when choosing an aging regime to correctly approach a realistic time frame (Cějka et al, 2013;Saison et al, 2010).…”

“…However, evidence points toward the valid prediction of aging compounds from studies comparing forcedaged to long-stored naturally aged beer (Cějka et al, 2013;Saison et al, 2009Saison et al, , 2010. Cějka et al (2013), for example, found that aging pale lagers at 45 • C for 6 days was equivalent to aging for 6 months at 20 • C. Therefore, it is worth pointing out that care should be taken when choosing an aging regime to correctly approach a realistic time frame (Cějka et al, 2013;Saison et al, 2010). Several forced-aging regimes can be found in the scientific literature (Bravo et al, 2008;Depraetere et al, 2008;Saison et al, 2008Saison et al, , 2010Wietstock et al, 2016).…”

“…It should be reinforced that the safest approach to use a forced-aging regime to study the chemical and sensorial relevance of a compound is to test the equivalence of such a regime to natural aging before using it. The use of multivariate statistic techniques is suggested when comparing sensory and chemical analysis data to validate such regimes, as done by Cějka et al (2013). The use of multivariate statistic techniques will be approached more detailed in Section 4.…”