By: Gerald Dlubala
Winemakers choose a yeast strain based on several enological characteristics, including its tolerance to temperature, ethanol and sulfur dioxide, ability to provide quality fermentation, and ability to produce the desired aromas with minimal potential for foaming or clumping. Each fraction of the yeast contains specific, targeting properties that allow them to aid in the fermentation process and improve the overall quality of the wine. Yeast is the catalyst for creating up to 80% of all of the aroma-active compounds found in wines, including two of the most important ones, higher alcohols and esters. Yeast derivatives, used to improve wine quality, color, oxidation and mouthfeel, can also mimic the effects of a wine aged on lees when using targeted products selected and identified by experts. The better a winemaker understands them, the better wine they will produce.
Using active dry yeast has become the preferred method for winemakers to get consistent fermentation and flavor complexity in their wines from batch-to-batch, negating much of the inherent risk of going with natural or spontaneous fermentation. Natural fermentation brings a high degree of unpredictability regarding starting times and stuck or sluggish fermentation cycles that can affect and diminish the quality, flavor and aroma of the wine. Conversely, active dry yeast is the freshest format available and ready to ferment upon contact.
Traditionally, the active dry yeast is poured onto the surface of at least 10 times its weight in room temperature tap water and gently stirred to avoid or break up any clumps. If needed, there is a 20 minute waiting period to acclimate and have less than a 10-degree Celsius (50 degrees Fahrenheit) difference with the tank temperature. Once it reaches the ideal temperature, the mixture is transferred into the tank with aeration. Additionally, most suppliers recommend the use of rehydrating agents, or yeast derivatives, in the rehydration water.
Expediting Fermentation While Reducing Costs: Fermentis E2U™ Yeast
Fermentis by Lesaffre, experts in the fermented beverage industry, offers an easier way for winemakers to start the fermentation process by streamlining the rehydration process or completely bypassing it with their line of certified E2U™ active dry yeasts.
“As a winemaker, it’s always great to have options,” said Fermentis Regional Sales Manager Anne Flesch. “With our E2U™ line of yeasts, you can direct pitch or rehydrate. It is the winemaker’s choice as to which method is the best for them at any given time.”
Flesch told The Grapevine Magazine that for practical purposes, the best way to direct pitch E2U™ is to pour the yeast directly on top of the tank, or, for whites and rosés, during tank filling after settling. When choosing to rehydrate E2U™, it can be accomplished under a wide range of temperature options, in water from 15-37 degrees celsius (59-98.6 degrees Fahrenheit).
“Whatever option a winemaker chooses, the wine’s organoleptic characteristics (flavor, wine and color) or composition (levels of alcohol acidity) are not compromised,” said Flesch. “Both standard and E2U™ protocols result in the same performance in fermentation kinetics, so it is ideal for the winemakers who are looking to expedite their process without sacrificing anything related to quality. When time is the most crucial, as time in the cellar during harvest, this helps save that time.”
Expediting the winemaking process and gaining more time always seems to be on the agenda for winemakers, and by direct pitching yeast, there are benefits throughout the entire process.
“By choosing to direct pitch E2U™ yeast, the amount of water and heat needed for yeast rehydration is decreased along with the amount of water, energy and additional products used to clean the rehydration materials,” said Flesch. “The winemaker is bypassing traditional rehydration and the time, labor and personal miscues that come along with that process. There is a reduction of chemicals, needed water and heat sources, and labor hours needed, reducing labor costs. A streamlined fermentation task is completed faster and results in saved time and higher quality of work with no investment in rehydration agents, materials or cleaning chemicals. In some cases, a winemaker may potentially be able to replace their propagating/mother tank.”
“Safety in the winery is also an important issue,” said Flesch. “Comfort and safety levels of production workers can rise by negating the need for extra water hauling or unnecessary ladder use. The possibility of dust inhalation from a yeast-derived product is a real health hazard for cellar workers during harvest. Our Certified E2U™ fermentation aids and functional products work to target and improve those conditions by offering a range of products that are under a physical form, like micro-granulated powder, or a liquified form that offers fewer inhalation probabilities and high dispersibility rates.”
Fermentis created the first yeast liquid autolysate, ViniLiquid, in its fermentation aid portfolio. It has many advantages, including increased safety, superior pump-ability, quick availability to the yeast and shorter fermentation versus using a dry autolysate.
“Conditions can dictate whether it is advantageous to rehydrate E2U™ before use, but if you choose to rehydrate, you can successfully do so using cold tap water, reducing heat consumption,” said Flesch. “For example, if conditions are toxic or challenging for yeast or your fermentation is stuck or sluggish, rehydrating E2U™ for use is recommended. Sometimes to completely restart a stuck fermentation, our protocol recommends the building of a starter culture. We do recommend rehydration in the case of secondary fermentation for sparkling applications.”
Flesch told The Grapevine Magazine that the ability of their E2U™ yeast to be directly pitched is due to the high quality and expertise behind the production of the active dry yeast. The strength of the membrane developed during the multiplication process and the drying technology is the key to producing active dry yeast that is highly resistant to rehydration conditions. E2U™ has a four-year shelf life from production date with a recommended unopened storage temperature of less than 20 degrees celsius (68 degrees Fahrenheit).
“In short, use of yeast and yeast derivatives certified E2U™ can benefit the winemaking community in critically important ways,” said Flesch. “Fermentation is easier, less time-consuming, and more worry-free. Seventy-five percent of winemakers use active dry yeast with their fermentations,” said Lesch. “If all winemakers decided not to rehydrate, we could save up to 600,00 hectoliters (~ 16 million gallons) of water and significant energy each year.”
“Yeast hydration is now a matter of preference, not efficacity, and yeast derivatives are easy and quick to use,” said Flesch.
Enhancing Natural Processes Through Biotechnology Research and Innovation: AEB Group
The AEB Group enables winemakers and brewers to improve their natural fermentation processes by offering custom-based solutions using biotechnology and treatment processes. They are the first North American company to develop reactivators to automatically and reliably rehydrate active dry yeast.
Marco Bertaccini, Regional Sales Manager, told The Grapevine Magazine that AEB Group researches and looks towards providing winemakers the tools and products to take on the latest consumer taste trends, including different strains of yeast and the use of derivatives to match current consumer demand.
“You know,” said Bertaccini, “in the past, the trend in wines has been the traditional big and bold flavors. For us, that meant using our FERMOL Meditterranée for the big, bold reds and FERMOL Chardonnay for the traditional whites. That demand for the traditional style of wine is still there, but not to the degree that it was. Consumers today are really into fresh, light and easy-to-drink wines with enhanced flavors.”
For Bertaccini and the AEB Group, that translates into focusing on ester development and the transformation of amino acids into acetate ester. Their current focus is on the increased demand for easy-to-drink wines that feature a fresher variety of aromatics, especially those including citrus. Through research at the University of Modena and Reggio Emilia in Italy, AEB Group has ascertained and developed yeasts that express more of the natural flavor and aroma profiles of wine styles currently in demand.
“We develop yeast extracts that boost amino acids for certain specific profiles,” said Bertaccini. “The nutrients and amino acids in juices naturally express varietal-specific profiles that we all would recognize. Since we know that aminos are precursors for esters, we can replicate and target specific aminos to produce more of what we want in any specific varietal.
“For example, we offer our FERMOL tropical strain for white wines, which enhances and delivers more of that fresh, citrus-based flavor and aroma in a Sauvignon Blanc. Chardonnay wines benefit from our FERMOL fleur yeast. For red varietals that already contain great, natural, fresh fruit and berry flavors and aromas, we’ve developed our FERMOL red fruit strain to enhance all of those desirable qualities. These strains use and enhance the unique oenological features of the wine to produce a wine that is easy to drink with fresher aromatics.”
Bertaccini told The Grapevine Magazine that AEB Group’s latest New Zealand trials featured their Levulia Torula strain and resulted in a huge success. Levulia Torula is an organic, non-saccharomyces yeast developed for varietal aroma enhancement. It is a strain for alcoholic pre-fermentation, present naturally in the native flora of the must, contributing positively to the organoleptic complexity of the wine while limiting the production of volatile acidity. Levulia Torula is used in sequential inoculations, 24 to 48 hours before a classical strain of Saccharomyces cerevisiae. Its rapid establishment in the must makes it ideal for limiting the spontaneous development of separate strains of unwanted native yeasts. After the growth of the Saccharomyces cerevisiae, the population of Torulaspora delbrueckii dies down and rapidly begins its autolysis during alcoholic fermentation, where it supplies nutrients and contributes to the detoxification of the medium. It also helps reduce the sensations of astringency in the mouth through the release of polysaccharides.
“We initially only made a small quantity for the trials, but it became wildly popular and quickly sold out,” said Bertaccini. “Levulia Torula provides excellent dominance in fermentation and great control over microorganisms. It is organic and usually paired with another inoculation for a strong fermentation finish. We are seeing the demand grow and now have much more available because of the success of our New Zealand trials.”
Because it is organic, Levulia Torula has a shorter recommended shelf life of two years and is suitable for all grape varietals, including Sauvignon Blanc, Chardonnay, Gewurztraminer, Colombard, Riesling, Muscat, Sémillon and more.
