Stability in the New World!

Stability in the New World!

Nearly two years ago, when the world stopped spinning, shelf-life became of paramount importance. Beer was left sitting for extended periods and all producers faced a hard audit. Draft service ground to a halt and a quick transition to package heavy offering was underway, perhaps permanently.

While imperial stouts and rich dopplebocks could weather the storm, as we approached six months in, a hazy IPA or delicate Kolsch was pushed past the breaking point. Flavors became quite dull and lifeless, aroma was non-existent, and any oxidation was well past obvious. Wet carboard and skunky aroma are unpleasant, however exploding fruit bombs may be the worst. Trends of unfiltered and supremely hopped beers were certainly showing their compromise. 
 

Westvleteren 6 and Westvleteren 12 age exceptionally well. Trappist monks have brewed here since 1839, however modernizations in equipment have occurred since that time. Since Westvleteren still uses no filtration or pasteurization, proper storage is key to prolonged acceptance. Failure to control environmental conditions during storage will result in protracted disappointment.

It is important to note, not all aging is negative. When it comes to finished beer, dark malts tend to condition especially well, expressing deep complexity over elongated periods. Styles with certain spicy or peppery phenolic compounds may transform to soft tobacco, leather, or vanilla. Hops will fade, inevitably, but this can focus attention to body and mouthfeel. Even oxygen can contribute some benefits with the development of wine and sherry like compounds.

After nearly a year of practical analysis, many brewers expressed new questions about extending stability. Resources on the subject are extensive, but details can be overwhelming. In a brief overview, we will discuss what brewers can do to help improve the life of their finished goods.

In order to stabilize beer, simply reduce the number of active changes taking place. Of course, this is easier said than done. There are a number of avenues to pursue, however tradeoffs will always be made. Start with a process audit to confirm the critical control points, then identify areas of concern. Review each area individually for opportunities to improve.

First and foremost, I always suggest tracking Dissolved Oxygen levels. Although countless factors influence stability in your finished product, DO levels will have the largest impact by far. Oxygen reacts with many different compounds inside beer, changing the flavor, aroma, and appearance. Poor packaging practices can see a nearly perfect product fail sensory standards in a matter of days.

Oxygen is such a large concern that even raw material can be negatively affected. Nearly every brewer is familiar with hops that have been exposed to open air for extended periods, however many are unaware that crushed grain can undergo a similar transformation. As short as overnight, milled grist can react with oxygen to “stale” product. Ultimately these changes lead to reduced shelf-life in finished product. Take extra care to preserve your raw materials!

Most brewers are well familiar with the concept of “stabilizing” yeast, either through fining, filtration, or centrifugation. Perhaps uncommon today is the use of metabisulfites to inhibit fermentation activity. Even less common is the use of non-thermal high-pressure pasteurization (HPP). Regardless of technique, the concept is the same; less biological life means less changing in the finished beer. Pasteurization is a traditional favorite, but some rebuff the flavor compromise. 

Microbiological stabilization is supremely important, however if care is not taken, yeast can be “inactivated” prior to full maturation of the wort. A proper fermentation is essential to long-term stability, so quantifying DO levels in cast out wort helps tremendously. Some yeast strains are prone to early flocculation and may drop out of suspension before re-metabolism of Vicinal DiKetones (VDK’s) can occur. In these cases, it may be necessary to take extended measures such as rousing or krausen to reach an acceptable threshold.
 

Although beer always tastes best out of fine glassware, keeping it canned prevents light-struck character. More than one international brand is known for a signature skunking effect when exposed to UV light, however modern advances prove beneficial. Hop extracts and specific glass coatings are just a few methods used to expand packaging options while protecting the contents. 

Not all changes come from living organisms. Particular wavelengths of ultraviolet light are detrimental to beer. “Skunking” is caused by the formation of methylbut-2-ene-1-thiol-3, a reaction induced primarily by sunlight. With the evolution of fluorescent and LED lighting, long-term floor storage can have more exposure risk than previous incandescent lighting. Brown glass should eliminate up to 85% of undesirable light, however aluminum cans and stainless kegs have an obvious advantage. Thankfully cans also offer advantages in an improved oxygen barrier and reduced weight. 

Without debating the finer merits of Arrhenius vs Eyring, it is safe to state that temperature and chemical reactions are correlative. Increasing mash or fermentation temperature is known to influence finished product greatly, so it should be no surprise that temperature of packaged goods can also have drastic impact. As it pertains to beer, heat will generally accelerate chemical reactions and change the product profile faster. 

Keeping beer cold is a no-brainer, but what about consistency? English breweries have long been known to “cellar” beer around 50-52°F, but this is quite different than the ice loaded caverns of traditional German lagering. Temperatures near freezing slow most chemical reactions to a crawl, helping to preserve flavor profiles longer. Unfortunately, fluctuations in temperature generate colloidal instability through cyclical formations of polyphenol-flavinoid complexes. This means that repeated heating and cooling cycles can generate a permanent increase in turbidity.

Tailoring the brewing process to maximize enzymatic activity will improve overall product stability. Enzymes are essential to the entire brewing process, so obviously they impact stability as well. Lowering the required input energy for a reaction seems like it would be at direct odds with stability, however when properly manipulated, enzymes can maximize reactions in short order. Enhancing the breakdown of amylose and amylopectin means fewer chances for glucose or maltose to free up inadvertently and ferment down the line. After efficient processing, there is less “reactive material” and therefore a more stable end product. 

Incorporating supplemental enzymes to your brew only takes seconds. Measuring out a dose and adding it to the mash or fermenting wort is relatively simple, but the improvements can be quite complex. Starch degrading enzymes can help free and convert saccharides for fermentation leaving behind few residual component pieces. The tightly bound “root structure”, or limit dextrins, that are left behind after amylase actions will contribute to flavor and mouthfeel, providing much of the finished product character. Balance starch conversion efficiency with malts high in limit dextrin to ensure good head retention, mouthfeel, and flavor.
 

Thick, rocky white foam on this altbier is enhanced by remaining limit dextrins. Rich flavor and color can be contributed, without excessive sweetness, when saccharification enzymes are cared for. In fact, high attenuating yeast or mashing schedules may require increases in high dextrin malt to maintain the intended flavor profile.

The mash can benefit from more than just starch conversion. Proper degradation of arabinoxylans and B-glucans will lead to greater extraction efficiency by way of lowering wort viscosity. A lower viscosity allows for a faster and more complete collection of wort. This is all great, but what about increasing stability? The early degradation of b-glucan and arabinoxylans can aid in post fermentation filtration. Beer free of these problem compounds will be significantly less likely to form haze, a known instability.

Second to Dissolved Oxygen, much attention is dedicated to attenuation levels. This is the best place to ultimately measure the combined results of saccharification, extraction, fermentation and conditioning. A lot can be interpreted from protracted cellar logs, so do not overlook the importance. 

If alternative ingredients are to be incorporated in a brew, such as un-malted barley or cereal grains with high gelatinization temperatures, then incorporating thermostable maltogenic amylases, and proteases is almost a necessity. Natural enzymes will be insufficient in quantity or degraded too badly to be effective in proper conversion. Targeting your attenuation levels is possible through manipulating concentrations of pullulanases and glucoamylases, among others. Using a combination of time, temperature, and dosage, it is possible to achieve very consistent attenuation over a wide range, even up to 95%! 

Fermentation is hard on yeast. In the event it has decided to drop before full maturation is complete, you may get a “D-bomb”. If you are unfamiliar with the term, Diacetyl is perhaps the best known off-flavor for its signature butterscotch taste and slick mouthfeel. VDK’s can be quite unpleasant in large concentrations, but have no fear, ALDC is here! The enzyme compound Acetolactate-Decarboxylase, or ALDC, is responsible for preventing the formation of diacetyl and 2,3-pentanedione (VDK’s) and converting them directly to acetoin and 2,3-pentandiol respectively. The latter compounds are flavorless, so this conversion process is often considered a marker for conditioning. If reducing maturation times by 2-14 days sounds appealing, consider incorporating this enzyme.
 

Diacetyl is one of many fusel oil compounds created during fermentation. While its butterscotch flavor is not strictly considered unpleasant, it is often considered a major flaw in craft brewing. Some compounds, such as isoamyl alcohol and acetic acid, may combine during fermentation to form pleasant esters. Isoamyl acetate is a well-known banana flavor prominent in Hefeweizen.    

 

Whether or not you choose to incorporate supplemental enzymes, consistency is a key to stability, as it is our best tool to predict the future. If it is not common practice, begin keeping a library of packaged products to conduct periodic sensory analysis. Track the changes each brand undergoes in different environmental conditions, to better understand improvement potential. Make targeted decisions when approaching change to ensure minimal disruption. No product will last forever, so consider your reasonable limits.

In the end, we are producing a moment in time, best enjoyed when first presented. Much like a chef does not present the steak until it has rested, brewers too have the responsibility to properly mature and condition product for optimal experience. Excellence is but a peak to fall from, and enzymes and brewing techniques are simply a larger plateau to rest upon before the descent. Improve your beer stability, but drink it before it matters!  
 

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