By: Gerald Dlubala
The world of yeast strains is large, diverse and ever-changing. Used in commonly recognized applications, including baking, brewing, wine production, plant care, cosmetics and dedicated spirits production, the strains can contain similar attributes. The differences come in how they react under varying conditions and temperatures, and those are both noticeable and noteworthy.
Experimentation and Exploration Contribute to New and Enhanced Choices
“These days, craft distillers are experimenting with virtually everything to provide differentiation in their spirit, and that means with yeast strains, too,” said Denise Jones, Technical Sales Support Manager with a focus in fermentation for distilling for Fermentis, experts in the fermented beverages industry.
“If it converts starch into sugar, any yeast can theoretically be used to make a wash that can become distillable alcohol. Variations in yeast strains produce varied metabolic byproducts that translate into different congeners in the fermentation and final spirit post-maturation. Some distillers are trying different individual or combinations of yeasts, including Belgian ale yeasts, traditional American ale yeasts, or even Champagne yeasts to ferment their mashes. Individual fermentations can be distilled as a blend or be distilled individually and blended later. When you consider how these then respond to different process conditions, temperature conditions, the initial sugar concentration, inoculation rates, nutrition values and more, either individually or in combinations, you can significantly affect the behavior of some yeasts and, consequently, their flavor profile.”
Jones said that distillers play a crucial role in yeast strain development by selecting and successfully using strains adapted for the products they want to manufacture. Yeast strains prove to be successful and reliable by distillers regularly practicing their craft while continuing on their quest to manufacture a product that offers unique characteristics, including sensory values, fermentation speeds, efficiency in sugar conversion and more.
“Distilling yeasts do possess similarities to those commonly used for wine, beer and cider. But many of the distilling strains have properties that keep the fermentation progressing in the more stressful and challenging sugar substrates present in distillers mashes and musts. Distiller’s yeasts are more efficient in converting sugar into alcohol, meaning the final fermentation is faster and drier with fewer residual unfermented dextrins left over. These strains work at a higher temperature and ferment more quickly, typically within 72 hours versus a beer fermentation that can last up to 14 days,” said Jones. “Additionally, yeasts that work quickly are advantageous to distilleries that look towards higher efficiency to maximize production and capacity within the shortest timeframe. Some strains address the need for greater heat tolerance, furfural tolerance, or the need to adhere to enzyme use regulations. Genetic compositions allow these strains to ferment larger sugar molecules and increase congener development that translates into more desirable aromas and flavors in the final product.”
“For example,” she said, “to produce whiskey in Scotland, the use of enzymes is not allowed, so strains that can ferment complex sugars are required. Whiskey also requires an aging process in barrels and some specific congeners produced by yeasts. Rum uses different types of cane sugar substrates, ranging from exhausted molasses with a high non-fermentable solid content to juice directly extracted from the cane. They are different worlds in terms of substrates, requiring strains that resist specific conditions. In short, we cannot pretend that a strain selected for wine and that has evolved in that environment can efficiently ferment a rum or whiskey. Likewise, a strain used to ferment sugar cane juice cannot properly ferment exhausted molasses. But cross-functionality is often possible and encouraged as an important tool for innovation.”
“Our distiller’s strains have been selected for their tendency to be robust in high-stress situations that can alter and restrain sugar metabolism of the cells. The distiller’s choice of strain can depend on different conditions related to heat development, fermentation substrate conditions, or desired production efficiencies. Fermentis yeasts are adaptable to various substrates under different conditions and can ferment in multiple mediums. In many cases, multiple strains offer the right characteristics to ferment a specific wash for a spirit. We also offer strains that demonstrate the ability to ferment just about any sugar they encounter. Having choices helps distillers by offering a wide range of possibilities when selecting a yeast for their unique facility and specific type of fermentable sugar substrate. Some distillers will use the same strain on many different products helping them streamline their protocol systems and manage their supply purchases.”
Included in those strain choices are the SafSpirit and SafTeq lines. SafSpirit yeast strains are selected to give a range of choice for an array of different sugar substrates to help the distiller more easily reach their goals. SafTeq yeasts are primarily chosen to ferment agave-based musts, which are very rich in fructose and can have larger amounts of furfural and saponin, both considered toxins and inhibitors of the fermentation process. Providing strains that tolerate these toxins helps the distiller achieve complete fermentation of the agave sugars.
“Fermentis offers a wide range of yeast strains for the distilled spirits world,” said Jones. “Our yeast’s ease of use and directed capacity to ferment various sugar substrates give distillers many choices with regards to their fermentation challenges while keeping the process as simple as possible. Understanding that no facility or situation is the same offers Fermentis an opportunity to assist the distiller in finding the best yeast and protocol to reach their goals. Every distillery has different equipment and support services for fermentation, so each producer must consider fermenter size, shape, cooling capacity, desired alcohol targets, intended flavors and desired aroma. Then, having a yeast supplier that can successfully assist you using these parameters ensures that your production expectations are met while saving time and money.”
Jones said that many distillers come to Fermentis aware of their production capacities and are absolute in what they want as far as fermentation goals. Others will have a general idea but are searching for the right product to develop new functionality and flavor ideals. Most want to find a way to differentiate their product from others by choosing a strain and protocol that provides uniqueness. All of these methods are successful and can result in a significantly different product from other market offerings.
“Fermentis will always be there to offer help, advice and information to steer a distillery towards a successful product delivery,” said Jones. “We are finding that many fermentations still won’t have the complete nutrition needed to have proper growth and metabolism. Finding the yeast strains and derivatives that work well with nutritionally deficient sugar substrates seems to be a general need within the industry. Fermentis has taken the lead in producing yeast-derived products that enhance those sugar substrates lacking the necessary nutrients needed for optimal yeast performance. Then, once a distiller becomes accomplished in fermentation, they’ll usually begin to consider flavors and aromas. The aroma of spirits consists of several hundreds of flavor active compounds produced at every stage of the process. Most of these substances are yeast metabolites produced during the fermentation process. Favorably enhancing the development of these metabolites seems to be the trend in spirit designed fermentations.”
Jones told Beverage Master Magazine that Fermentis adds incredible value to each of their customer’s fermentation needs by consistently providing their technical and sales managers with the latest research information from their France-based research and development facility, including intuitive conclusions and details about each strain within a variety of different fermentation situations. With this information, distillers can make the right choices in yeast strains to reach their fermentation goals.
Experience and Expertise Lead to New and Successful Adaptations
Reaching fermentation goals is also a priority of Maryse Bolzon, Global Craft Distilling Manager of Lallemand Biofuels & Distilled Spirits, a global leader in the development, production and marketing of yeast, bacteria and specialty ingredients.
“In a distillery, whatever the size, the only way to produce ethanol and get that desired distinctive and unique aromatic profile is to choose the right yeast strain and use it in the correct conditions during fermentation,” said Bolzon. “One of the magical qualities of yeast is that you can make changes within the conditions of fermentation while using the same yeast and get noticeably different results. Subjecting the same yeast strain to different temperatures or different feedstocks will give similar yet distinctively different aromatic profiles to your spirits. Distilling yeast uses various types of sugar depending on the raw materials used and can reach higher ethanol content, ferment in stressful conditions, and develop deep aromas and flavors. Ultimately, the strain you choose should be aligned with the substrates used and under what conditions your fermentation occurs.”
For example, Bolzon said that in the production of whiskey, scotch and bourbon, selected yeasts should work well on grain under a wide range of temperatures, and as long as the substrates are similar, you can use the same strain of yeast with all of them. Conversely, different substrates, like those in rum, produce different sugars, requiring different yeast strains. If you work with 100% malted grain at 34 degrees Celsius throughout the fermentation process, you couldn’t use the same yeast strain when working with molasses under the same conditions. Rum uses glucose, fructose and sucrose, while whiskey will have glucose and maltose.
“Saying that, we understand how important it is to take the time to research and choose the correct yeast strains by researching and matching them with the types of sugars that they ferment,” said Bolzon. “Some ferment glucose and fructose, others fructose, maltose and maltotriose. Some will never ferment fructose under any conditions. There are a lot of choices, so consideration is always given to the spirit being crafted and the substrate in use, whether it’s grain, molasses, agave, syrup, fresh juice or something else, and we always look at the distillery’s fermentation and distillation conditions.”
A yeast supplier should be both a partner and assistant in the craft distiller’s process. They should understand the distiller’s identity and branding needs as much as the fermentation process and distillation conditions to provide the appropriate yeast strains to fit the distiller’s needs.
“Of course, choose a supplier that will provide dedicated technical support,” said Bolzon. “Within LBDS, our technical support is the cornerstone of our identity, with all team members having practical backgrounds in fermentation and distillation. We work closely with craft distillers to ensure that the yeast, nutrients, enzymes and bacteria chosen will provide the desired results. Our yeasts are stored in warehouses under optimal conditions, meaning no heat or direct sunlight. Our yeast is distributed in a dried state, meaning that we have removed the water, including the membrane. The membrane is critical to where the sugars, vitamins and minerals enter and the ethanol and other metabolites exit. If these exchanges do not work optimally, the yeast will not work properly and cause weak, sluggish or stuck fermentation. Making your yeast happy is always the key to successful fermentation, so if you’re working under potentially stressful conditions and want higher ethanol content, we recommend rehydrating the yeast before adding it to the fermenter. After purchase, the yeast should be stored in dry areas away from heat or direct sunlight. Because our yeast is sparged with inert gas and vacuum packed, you have up to three years shelf-life storage capability as long as the vacuum packaging remains intact.”
Bolzon said that LBDS is always happy to work with the distillers and assist them with producing dedicated spirits. Some distillers know exactly what they want in a yeast strain, others ask for help and support in developing their spirits, and others already have the knowledge but prefer to collaborate.
“I think as an industry, we cover the basic needs of distillers, meaning good fermentation kinetics, quality stress resistance and exceptional aromatic profiles,” said Bolzon. “But within LBDS, we believe that a distinctive spirit needs more than the basics. Perfection comes in the details, so we are constantly working to make improvements and offer new and stronger yeast strains that bump up bacteria synergy, impact nutrition and deliver more distinctive profiles. Every day, we have new questions about fermentation on specific substrates like coconut juice, exotic fruits, various syrups and more. These types of questions push us to a better understanding of raw material characteristics, leading to better yeasts, processes and partnerships with distillers.”
“To me, the most important thing is to make sure that the craft distiller receives quality technical support when needed to assist not only in yeast choices but also on processes like fermentation times, temperatures, nutrition information, and distillation procedures,” said Bolzon. “Within LBDS, we have Research & Development labs in the United States and Canada. We focus on the kinetics and aromatic profiles of our current strains. We work on adapting new strains to be successful under stressful conditions, and we work on providing strains that work under higher temperatures, benefitting the craft distiller that finds the cost of fermenter cooling prohibitive. We follow current trends, including the development of strains that enhance the aromas of distilled spirits.”
“In the end, the most important thing for us as a yeast supplier is to understand what the distiller is looking to accomplish with their product,” said Bolzon. “After all, that spirit will reflect their personality, brand and identity, so we must do all we can to help them with their goal of distilling a distinctive, unique product.”