Microscopy in Brewing: Applications and Advantages

The microscope has long held a place as an important tool in the brewery. Proxima is taking the application of microscopy to the next level as part of our line of affordable and approachable brewing industry services. Read on to find out all the ways the microscope can add valuable information to your brewing operations.

Expert Microscopy

Many brewers use the microscope as an efficient and straightforward way to check their brew for yeast or contamination and to diagnose the cause of unwanted haziness and sediment. We think the microscope is a great tool in the brewery too. However, an issue for our clients is that while they are expert brewers, they are not always expert microscopists, and it can be tough to confidently distinguish bacteria from protein aggregates or other debris. Proxima’s experts, on the other hand, are trained in doing just that, and through application of specialized methods we can definitively distinguish common microorganisms and materials present in beer.

Illuminating Your Beer with Darkfield Microscopy

Our first step is always to study the beer or wort sample under the microscope using darkfield illumination. This microscopy method is not widely available, so this is a great reason to send your samples to Proxima. With darkfield microscopy objects such as yeast, bacteria, and haze particles show up brightly against a dark background. Figure 1 shows a typical wort immediately prior to pitching, it contains scattered protein aggregates which will degrade and settle during fermentation.

Figure 2 shows a typical beer at the end of fermentation and shortly before bottling. There are scattered yeast cells. The cells in this sample are normal but too many dead yeast cells cause “brothy” off-flavors and microscopy is a great way to detect this.

Figure 3 shows beer contaminated with lactic acid bacteria. The bacteria can be seen clearly as small rods among the yeast and protein aggregates that are typically present. Following examination under darkfield, we use phase contrast microscopy to gain more information about what is present in the sample. Phase contrast allows clearer detection and identification of haze-causing materials and sediments.

For example, Figure 4 shows crystals of calcium oxalate found in a beer sample. Oxalates are present naturally in barley and when not removed by adequate calcium in the mash they are a common cause of sediments and so-called beerstone.

Causes of Haze in Beer

Haze in beer can be characteristic of certain styles, while at other times a bright beer free of haze is the goal. When facing a problem with undesired and persistent haze in your beer selective staining and microscopy is an excellent method for diagnosis. Treatment of the sample with the dye Eosin Y can identify protein aggregates by staining them pink as shown in Figure 5.

Haziness caused by protein aggregates is the most common and easiest to remedy through additional cold crashing and fining. Haze caused by starch is diagnosed by staining with an iodine solution (Figure 6) and haze from polysaccharides such as β-glucan can be detected with Thionin staining.

Starch haze is usually due to incomplete mashing while non-starch polysaccharide haze is usually due to milling of the grains too finely resulting in small particles remaining suspended in the beer. Polyphenol haze is diagnosed by staining with Methylene Blue (Figure 7) and suggests oxidation or overextraction of tannins from the malt. Using Proxima’s inexpensive and rapid turnaround microscopy services you can easily determine whether your hazy beer can be saved and pinpoint the causes of haziness to prevent it in the future.

Yeast Viability and Microbiological Testing

Yeast viability testing and cell counts are useful when there is concern that dead yeast has caused a stalled fermentation or off flavors and when posting up your own yeast prior to pitching. Figure 8 shows yeast cells stained with Methylene Blue which turns dead cells blue while leaving living cells colorless. Sometimes undesirable microorganisms end up growing in wort or beer. While it is rare for the types of bacteria or wild yeasts that can survive in beer to be cause health concerns, they can certainly cause undesirable off flavors. Lactic acid bacteria added to kettle-soured beers can also sometimes survive pasteurization steps and have a negative impact on the final product. In all these cases it is desirable to test for contaminating microorganisms. Several media have been developed and are commonly used to differentiate and identify wild yeasts and common beer spoilage bacteria such as Lactobacillus and Pediococcus,but most of the time it is simply enough to know if contamination exists. Proxima has developed a proprietary media with this in mind that rapidly detects a broad range of yeasts and bacteria in brewery samples, allowing our clients to inexpensively monitor for microbial contamination. When contamination is detected, Proxima can deploy the usual repertoire of media such as HLP, UBA, WLD, LMDA, and Lysine Agar upon request for further identification of the contaminating organisms. Figure 9 shows colonies of Lactobacillus from a contaminated beer sample plated on our proprietary medium.

Add Expert Microscopy to Your Brewery

In this post we’ve shown the many ways in which microscopy and microbial analysis can benefit brewery operations. While virtually every brew master would agree that more information about your mashing, fermentation, and finished beer is beneficial, we understand that margins in the brewing industry are razor-thin, making set-up of an in-house lab to perform these tests cost prohibitive. That’s why Proxima has developed our line of affordable rapid turnaround brewing industry services, including microscopic and microbiological analysis, that put top-quality data and information in the hands of even the smallest brewers. Check out our brewery services page for a full list of services we offer and reach out to us for a free consult to explore how we can support your brewing goals. We look forward to supporting you as you make great beer!