By: Alyssa L. Ochs
Without yeast, there would be no such thing as the modern form of beer we have come to know and love. This fascinating microorganism is responsible for the essential fermentation process of this beloved beverage. As a living organism and unicellular type of fungi that consumes sugars to produce carbon dioxide and create alcohol carbonation, esters and phenols, yeast influences the quality of a beer and the properties that make it unique.
Meanwhile, yeast is also valuable for making cider and spirits by impacting flavors and alcohol content during fermentation. Certain yeast strains have proven beneficial for these purposes, while proper yeast measurement and management are critical for a successful craft beverage. To learn more, Beverage Master Magazine connected with industry experts to explore the topic of using yeast in breweries, cideries and distilleries.
Types and Variations of Yeast
Various kinds of brewery yeast are available to aid craft beverage production, including ale, lager, wheat beer and Belgian yeast strains. Yeasts, such as champagne, wine, beer, wild and cider-specific yeast, are also available for making cider. Craft spirit distillers have traditionally used the saccharomyces cerevisiae species of yeast because of how it converts sugars and produces consistent alcohol without adding off-flavors.
Hybrid yeast strains that cannot be categorized into the typical types are available and work well when other yeasts are too warm for lagers or too cold for ales, for example. Hybrids can be beneficial for altbier, Kolsch, blonde ale, cream ale and American wheat beer styles. Gene-edited yeasts are genetically modified to achieve more creative flavors and opportunities to mix beer yeast strains to achieve complementary characteristics. While non-saccharomyces were once considered contaminants in brewing and winemaking, recent research suggests they may provide unique sensory characteristics and future potential. All of this goes to show that there’s a lot more to yeast than what you might initially expect in the craft beverage industry.
Fermentation Products for Spirits – Lallemand Biofuels & Distilled Spirits
To discuss the distilling side of yeast, Mitch Codd, the technical sales leader for Lallemand Biofuels & Distilled Spirits, told Beverage Master Magazine about his company’s role as a leading supplier of fermentation ingredients and how it provides distillers with high-quality yeast, nutrients, enzymes, bacteria, tech support and education programs.
Codd explained how saccharomyces cerevisiae have been utilized, domesticated and bred for thousands of years. He said that in doing so, humans have selected traits advantageous to whatever application they need, such as baking, brewing beer or making whiskey. Because of this domestication and selection, we now have different types and strains to choose from, each exhibiting unique characteristics from one another.
“In distilling, there are several important factors that should be considered when choosing a yeast strain,” Codd said. “In the production of spirits, our main goals for fermentations are to utilize all available sugars while also producing desirable flavors and aromas. We may also wish to reduce the production of flavors as much as possible, in the case of making vodka. Both flavorful and neutral spirit productions are feasible and may require a specific yeast selection.”
“Interestingly, some strains of yeast will utilize maltotriose, a common sugar found in whiskey fermentations, while others may not use them at all,” Codd continued. “The same goes for rum yeast or agave yeast. Molasses will contain high amounts of sucrose while agave fermentations can be high in a sugar called fructose, which can be difficult for some yeast to fully utilize. If we choose a strain of yeast specifically intended for rum or agave, the fermentation will finish dry, and we won’t be sending these valuable sugars to the still. The esters and congeners that each of these strains produce are quite specific to the genetics of each strain. A rum yeast may produce a very high level of isoamyl acetate, responsible for the ripe banana flavor in a heavier rum while a whiskey strain may produce lower levels of Isoamyl acetate but higher levels of phenethyl acetate which would bring a rose or floral note to a good rye whiskey. The strain of yeast we choose for our fermentation can dramatically impact our total amount of spirit produced, as well as the actual flavor and aroma of the final spirit.”
Customers often ask the Lallemand Distilling team whether a beer or wine strain of yeast can be used for spirits. Codd says that the answer is “maybe” because the strain of yeast chosen is often very specific to the type of final product.
“Some beer strains can produce a lot of aromas and flavors,” Codd said. “For example, saison strains will generally produce a lot of isoamyl acetate. If that is specifically something we want in a whiskey, it may be possible to use this strain for that fermentation. Oftentimes, however, this will come with fairly significant drawbacks. In the case of using a beer strain for whiskey, one of the more common issues would be with sugar utilization. Earlier, I mentioned that maltotriose, the three-chain sugar molecule, can be very difficult or impossible for some yeast to utilize. A lot of beer strains will never use this sugar, as it is usually desired to have some sweetness left over in the final beer. In distillation, this sugar will never actually show up in the spirit, but it will burn in the still and create off-flavors in your final spirit.”
“The same concept goes for using wine strains in distilling,” said Codd. “There may be some cases where this practice could make sense and produce a great spirit, but more often than not, a quality distilling strain will produce a far superior product than a beer or wine strain in the same conditions. Since the science of distilled spirits production has advanced so far recently, there are great yeast strains specific for distilling that will help you achieve any goal with respect to flavor production.”
Yeast Measurement and Management – Aber Instruments
Not only is the type of yeast important in beverage production, but also accurate yeast management and understanding how many live yeast cells are helping you achieve your production goals. Aber Instruments Ltd., UK, headquartered in Aberystwyth, UK, specializes in yeast measurement and management solutions for the brewery industry. They also have an office in Alexandria, Virginia to better support their customers in the Americas. Aber’s yeast monitors are designed to be used in real-time to measure live yeast concentrations. Its Online Compact Range features the flagship Compact Yeast Monitor, the Compact Adapt and the recently released Compact PerfectPitch mobile skid to improve pitch performance and consistency. Meanwhile, Aber’s Countstar Yeast expedites and automates lab yeast readings.
All major brewing groups and many innovative craft brewing companies, including Summit, Marble and Meantime, have trusted Aber to optimize their pitching and production processes. But in addition to offering these products for effective yeast management in the brewing industry, Aber is engaged in industry research and has published the findings of multiple studies in scientific journals and magazines.
For example, Aber Instruments introduced the concept of a portable yeast pitching skid for craft brewing and aimed to scale this new technology for smaller breweries. The London-based Meantime Brewing Co. performed a case study to assess the PerfectPitch product’s functionality and found significant improvements in yield and predictability in the pitching process, concluding that the unit ultimately pays for itself. In the case of the Meantime Brewing Co., the Aber PerfectPitch helped reduce fermentation times and improve productivity by up to 25 percent without needing to invest separately in real estate. In a separate study, Aber reported on the process improvements of a yeast monitor tested in South Africa after checking the real degree of fermentation and ferment rates before and after its installation.
To assess a new rapid automated yeast cell counter that uses a bright-field microscopy and dye-exclusion method, the Aber Countstar Yeast, the company published an article with promising findings in the Journal of the Institute of Brewing & Distilling. According to the report, “The automated cell counter successfully reduced inter-operator errors, a major hindrance with manual analyses. Tests carried out at a brewery in the UK demonstrated that the cell counter provides consistent counts for assorted yeast strains. External tests highlighted the instrument’s ease of use and consistency among different strains of brewing yeast and various stages in the brewing process.”
Yeast Recommendations and Innovations
Dr. Aditya Bhat, the vice president of technology for Aber Instruments, told Beverage Master Magazine that in his experience of supporting the craft brewing industry over the years, depending on the size of the brewery, craft brewers either acquire yeast from a yeast supplier or they grow and propagate their own yeast. Yeast purchased from a supplier, usually in dry form, must be rehydrated before it is used for pitching and fermentation and monitored for the yeast’s quality and viability.
“Typically, larger brewers have a cut-off viability percent, below which they will discard the yeast,” Bhat said. “Depending on the brewery, this is typically around 85 to 90 percent viability. The presence of dead cells is detrimental to the final quality and flavor of the beer, hence the importance to check viability. For craft brewers, you would want to use a simple, easy-to-use, plug-and-play technology for this estimation. Something like the Aber Countstar Yeast works really well. It is sometimes known in the brewing world as a ‘lab-in-a-box’ – technology that calculates parameters like live cell count, dead cell count, viability, cell size, percentage aggregate and circularity index in just a few minutes from preparation to measurement.”
For yeasts propagated in-house, Bhat said that monitoring the propagation in real time has several benefits and can be done using the Aber Compact or Compact Adapt Yeast Monitor.
“Aber technology will enable you to track the entire propagation process, identify whether the process is going well or is deviating from expectation, activate troubleshooting steps if necessary, save time and energy because of real time monitoring and action and identify when there are enough yeast cells in the propagator to pitch the next brew,” Bhat said. “It makes planning a lot easier, and better planning typically leads to an increase in productivity.”
There are many things to look forward to with craft beverage yeasts and exciting innovations, such as gene-edited yeast strains. Codd from Lallemand Biofuels & Distilled Spirits explained that a strain of yeast that has been gene-edited is a natural yeast but has been “steered” towards expressing specific characteristics through the intervention of lab methods and DNA editing.
“Sometimes this has a sort of ‘spooky’ connotation to it, but in reality, using these methods can be incredibly safe and specific with the results that are achieved,” Codd said. “With modern day methods, the changes that are made are precise, and oftentimes they are just changes that boost or suppress natural pathways the yeast is already expressing.”
Codd said that gene-edited yeast strains are a fairly new concept to the distilling industry, with no real precedent yet for use but plenty of promise. In adjacent industries like brewing, these strains seem to have been embraced with open arms, and use was adopted very quickly when they became available.
“Strains like Lallemand’s “Sourvisiae” beer yeast, which is able to produce sour beers in a single-step fermentation without the need for kettle souring or bacterial additions, are now commonplace in breweries across the country,” Codd said. “I believe the distilling industry would be a fantastic next step for the use of these strains, and there are plenty of really interesting opportunities that it presents. With the recent focus across our industry, and the world, on sustainability, gene edited yeast could help us make big strides in reducing the footprint spirits production has on the environment.”
But while it is easy to get wrapped up in these more “flashy” innovations on the horizon, Codd said there’s also a lot of promise in some of the more traditional strain development methods.
“The microorganisms that are responsible for fermentation have an incredible amount of genetic diversity, all with their own unique characteristics,” Codd said. “It’s reasonable to assume that, with that much diversity, there are some really exciting expressions of yeast strains just waiting to be found out there. Every strain we use today has to be discovered at one point in time. The exciting thing is that now we have whole laboratories and companies devoted to searching for or prospecting for these future strains, Lallemand being one of them.”
“We may find that we can breed various strains together and get an even better flavor expression from the new yeast, or we can search in interesting historical environments and bring a historical strain to market that creates a whiskey similar to what George Washington would have produced,” Codd said. “With new methods, we can screen enormous libraries of yeast and use powerful analytical methods to see exactly what congeners they produce and how well they ferment our intended mash or wash. Most of the next generation of yeast strains will likely be from our tried-and-true species saccharomyces cerevisiae, but there are also several other genres of yeast that seem interesting, colloquially known as ‘non-sacch’s.’ These may prove to be a valuable addition to the distiller’s toolbox in the future.”