Malt Quality and the Art of Delaying Beer Flavour Staling
TLDR:
The Barley Makes the Difference: The type of barley used for malting and how it is processed (the malting process) plays a big role in how long your beer keeps its flavour. The best kind of malt is one that has less of certain chemicals (like lipoxygenase and nonenal) and more of others (like antioxidants and reducing compounds).
Why Beer Loses Its Flavour: Many things can make beer lose its flavour over time, including how it's stored and packaged. However, certain chemicals like aldehydes, which are found in malted barley, have a significant impact on this. Some aldehydes formed during a process called Strecker degradation also contribute to this change in taste.
The Power of Antioxidants: Malted barley has antioxidants - chemicals that can slow down other chemical reactions that might spoil the beer's taste. If we protect these antioxidants during the malting process, we can make a brew that keeps its flavour for longer.
Introduction
The complexity of brewing good quality beer goes far beyond the basic ingredients of water, barley, hops, and yeast. A profound understanding of the chemical processes, the ingredients involved, and their influence on beer's final quality is crucial. Of particular importance is the intricate interplay between pro-oxidant and antioxidant activities in malt barley that can significantly impact beer flavour stability or, in simpler terms, delay beer flavour staling. This article reviews the latest journal article by Guido et al. (2023) on the impact of malt on beer stability.
Malting Barley's Role in Beer Quality and Stability
Malting barley stands as the backbone of brewing, offering not just the fermentable sugars but also influencing the beer's colour, body, and, more importantly, flavour. Different types and qualities of malt contribute variously to beer's flavour profile, either enhancing or detracting from the final product's taste.
Crucially, malting barley and the malting process significantly impact beer instability due to the balance between pro-oxidant and antioxidant activities. These biochemical processes, involving compounds present in barley or formed during the malting process, play an instrumental role in brewing. Given the gravity of this balance in the overall beer quality, the brewing industry's interest in understanding the properties of barley malt and the malting process is on the rise.
The Science of Beer Staling
Beer staling is a complicated affair, affected by multiple factors ranging from storage conditions to the packaging process. However, volatile carbonyl compounds like aldehydes are often spotlighted as the primary perpetrators of beer flavour instability. In particular, unsaturated aldehydes with low sensory thresholds like E-2-nonenal are considered chief culprits. Known to evoke a "cardboard" character in aged beer, these aldehydes can form during malting and mashing via enzymatic and non-enzymatic degradation of polyunsaturated fatty acids.
Interestingly, not all aldehydes are flavour villains. For instance, is E-β-damascenone, a terpenic ketone that adds a "stewed apple," fruity, and honey-like note to a 6-month-old beer sample.
The Strecker Degradation and Beer Staling
Another key player in the chemistry of beer staling is the Strecker degradation. This chemical reaction involves an amino acid and an alpha-dicarbonyl compound (intermediates in the Maillard reaction), resulting in aldehydes. Aldehydes like 2-methylpropanal, 3-methylbutanal, and phenylacetaldehyde, resulting from the Strecker degradation, can be found in higher concentrations in malt compared to other types of aldehydes.
Despite being understudied, these aldehydes are a significant part of the beer staling puzzle, demonstrating that both lipid peroxidation and the Strecker degradation play vital roles in creating flavour profiles during malt production.
The Potential of Antioxidants in Beer Stability
Interestingly, malt barley doesn't just contribute pro-oxidants to the brewing process; it's also a source of natural antioxidants. Polyphenols and phenolic acids in malt can delay, retard, or prevent oxidation processes, effectively acting as inhibitors of oxidative damage. Their contribution to malting and brewing is so significant that some brewers are now looking at preserving these endogenous antioxidants during the malting process to bolster the brew's reduction potential. The idea is to harness these antioxidants to counterbalance detrimental oxidative processes, ultimately improving beer flavour stability.
Concluding Thoughts: Translating Theory Into Practice
In essence, the quality of malt - underscored by its pro-oxidant and antioxidant balance - is a significant determinant of beer flavour instability. Optimal malt characteristics include low lipoxygenase activity, low residual nonenal potential, free phenolic compounds with high antioxidant activity, and a high amount of reducing compounds.
Taking this scientific insight into the brewery, practical applications could transform brewing strategies and outcomes. Brewers, for example, could work with maltsters to carefully select barley varieties that exhibit these favourable characteristics. Moreover, adjusting the malting process parameters to preserve endogenous antioxidants during malting could be a focus of future malt production protocols.
In addition, this understanding could prompt brewers to fine-tune their brewing techniques. For instance, they could incorporate specific brewing steps aimed at minimising oxidative damage, such as implementing low oxygen brewing methods or careful temperature control during mashing to prevent excessive degradation of polyunsaturated fatty acids.
Furthermore, scientific advances in this field may also pave the way for the development of novel brewing additives, such as specialized antioxidant-rich adjuncts, or tailored yeast strains capable of managing oxidative stress during fermentation.
Finally, this knowledge could be leveraged to improve storage and packaging techniques to further delay flavour staling. Employing packaging methods that better protect the beer from oxygen exposure, or experimenting with storage conditions that slow oxidation, could add further stability to the beer's flavour profile.
In the end, the journey to stall beer staling and preserve flavour begins at the most basic level - the malt. As we deepen our understanding of the delicate balance between pro-oxidant and antioxidant activity in malt, we open new avenues for enhancing beer flavour stability. This progression not only benefits the brewing industry but also ensures that beer lovers worldwide continue to enjoy their favourite brews, just as they are meant to taste, for longer.
Article Reviewed:
Guido, Luis F., and Inês M. Ferreira. 2023. "The Role of Malt on Beer Flavour Stability" Fermentation 9, no. 5: 464. https://doi.org/10.3390/fermentation9050464