The Beer Scientist
Exploring the key analytical techniques used throughout the brewing process – and the importance of sample filtration
sponsored by Cytiva
Presenting highlights from the Mark Eurich’s webinar “Analytical testing in brewing,” which is now available to view on demand at: https://bit.ly/2QbzGU0
As Plato (supposedly) said, “He was a wise man who invented beer.” Though it is believed that beer was first “invented” in China over 9,000 years ago, the Western brewing process most of us are familiar with seems to trace back to Mesopotamia – between 3500 and 3100 BC. Since then, everyone from Greek philosopher Sophocles to Saint Arnold (the patron saint of hop pickers) has tooted the life-sustaining properties of this intoxicating substance. Now, there are over 22,000 active breweries worldwide, and many brewing labs rival research labs from a technological standpoint. So, let’s delve into the analytical chemistry behind one of the world’s favorite beverages…
I’m the Raw Ingredients Quality Assurance Manager for the New Belgium Brewing Company. I started with the company in 2014, and played a key role in the buildout of a new brewery in Asheville, North Carolina. On this project, I also set up a quality assurance team and acted as its manager for five years before starting in my current role. Over the years, I’ve held quality and analytical roles at Coors and MillerCoors for just over 20 years, and have conducted some great research into beer flavor stability. I’ve also been an active member of the American Society of Brewing Chemists since 2007, and have served on the Board of Directors of the American Society of Brewing Chemists, acting as both the Publications Chair and the Technical Committee Chair.
The beer necessities
The brewing process begins with raw ingredients – water, malt, hops, yeast, carbon dioxide and spices (amongst other things). Throughout brewing, sensory (visual, taste and aroma) testing is a key part of the analysis, but many other tests are performed at the raw ingredients stage.
Let’s start with water, as it makes up around 95 percent of what’s in your glass. A lot of water analysis is performed at your municipal water supply – so I suggest you check your reports closely – but other tests include checking for free chlorine, pH, and microbes. There are two common yeast strains used in beer brewing – one for lagers and one for ales – so microbiological analysis is important for assessing not only yeast health, but strain type.
Carbon dioxide, which is used extensively throughout the brewing process, is mostly analyzed by suppliers using GC. Malt suppliers also perform a range of tests to ensure that the malt tastes and smells as desired. In fact, these labs probably use more fluted paper filters for sample preparation than any other kind of lab. And after harvesting, hops are analyzed for moisture, acids, and oil content.
Obtaining the perfect sample
Many sample filtration and preparation materials and methods are used throughout the brewing process to ensure accurate analysis. These include gravity and decant filtration, centrifugation, filter paper, glass fiber filters, filter discs, solid-phase extraction, vacuum filtration, and diatomaceous earth. It is critical that the right sample-preparation method is used for the attribute you are measuring – you don’t want to inadvertently remove the compound you’re measuring, but you also want to ensure any interferences are filtered out.
Wort – the sugary part of beer – should be analyzed for a number of attributes, including clarity, density, color, bitterness, pH, fermentable carbohydrates, metals, and proteins. It is equally important that carbon dioxide is also addressed from fermentation through to packaged product. If not, it will greatly impact the analysis being conducted. Pouring, sonication, filtration, gas purging, membrane degassing, vacuuming, microwaving, and shaking are just some of the methods used in these analyses.
Fermented beer is arguably the most difficult sample to analyze because of its complexity. It is at this step of the brewing process where the key characteristics are created. For density, alcohol and pH evaluation, filter paper or centrifugation can be used to prepare the samples. For yeast health evaluation, the sample can be diluted prior to testing. And for other microbiological testing, the sample can be plated or subjected to vacuum filtration.
The final product
To analyze mature or aged beer, yeast must first be removed by centrifugation or settling. Some breweries use other forms of yeast removal, such as crossflow filtration. Filtration is crucial because if carbon dioxide is not properly removed, the measured pH could be artificially low due to the presence of carbonic acid. Particulate or haze should also be carefully filtered to ensure proper color evaluation.
To achieve a bright beer – beer with little or no haze that is visually stable throughout its shelf life – you need to add an extra filtration step; for example, centrifugation, diatomaceous earth, cellulose-sheet filtration, or cross-flow membrane filtration. Once the beer is packaged, sample preparation is quite simple, but any carbon dioxide must be carefully removed once again.
Ask the Expert
Do big breweries and microbreweries do different tests?
Larger breweries and smaller breweries certainly have different laboratory capabilities. The larger breweries can often use more complex instruments, but there’s usually a way for a smaller facility to make the same measurements.
Do you think a more detailed metabolite profile of beer via GC or LC is needed for consistency in the future?
With the cost of these tools decreasing, I can see that being a possibility. GC is a tool that we utilize to maintain consistency in our beer products, whether it’s volatiles or organic acids. With the purchase of more expensive instruments, you also need more highly skilled technicians. But still, these are currently used in some smaller facilities so I do see it happening in the future.
What analytical instruments are used to measure bitterness?
The most common is extraction. There are also more sophisticated methods, such as (U)HPLC. One technique I didn’t really touch on in the presentation is segmented flow analysis, which is more complex and has a higher throughput. The other one would be your sense of taste!
If you missed the webinar on this topic, you can view the on-demand video at: bit.ly/2QbzGU0. Cheers to that!