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Learn the essentials of lager beer from one of Germany’s most respected beer institutes. Join Mathias Hutzler from the Research Center Weihenstephan for Brewing and Food Quality (Technical University of Munich) for a discussion of lager beer history and production methods followed by a presentation of modern lager yeast and fermentation solutions by Eric Abbott (Lallemand Brewing).
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Yeast, the most necessary ingredient in beer, arrives at breweries in many forms. Today we consider dry yeast and the role it can play in brewing and fermentation. John Holl spoke with Jan-Philippe Barbeau, the regional sales manager for Canada at Fermentis by Lesaffre about the product and how brewers can best implement it into their processes and recipes.
With the talk of shifting hop regions and the continued rise of local maltsters, let us not forget yeast. The miraculous microbe lives all around us but unless we’re talking about coolship ales, there is not much of a focus on brewing with local yeasts.
Several years ago Bootleg Biology in Nashville, TN launched its Local Yeast Project and touted itself as the “first organization to pioneer the collection and cultivation of official local yeast strains for every U.S. postal code and country across the globe, beginning with the original S. Arlingtonesis™.”
Finding and isolating and then using a local yeast strain – one in immediate proximity to a brewery – adds an unrivaled dimension to a beer. Beer Edge Editor John Holl spoke with Jeff Mello the Chief Yeast Wrangler of Bootleg Biology about the project and its benefits.
In a relatively short time, historically speaking, brewers have rediscovered Kveik and been using it in earnest. The Norwegean yeast has helped cut fermentation times way down, a boon for small breweries looking to quickly get beer, especially IPAs to market.
Dr. Richard Priess the director of Escarpment Labs recently spoke on the All About Beer podcast about how the yeast has gained in popularity and what is still being discovered and mapped out.
While hops get a lot of the attention from brewers and drinkers alike, and malt has intrigue, especially as the craft segment of that ingredient is on the rise, there is another area that deserves renewed focus.
Yeast is the workhorse of beer and while it is critically important, it can sometimes be taken for granted. Still, there are several advancements happening with the microbe in labs across the globe and Lance Shaner, the owner of Omega Yeast recently spoke with Beer Edge editor John Holl about innovation in the yeast space.
The quality manager at Allagash Brewing Company shares some insight into the brewery’s yeast program.
Remember the old saying: brewers make wort. Yeast makes beer. The marvelous microbes responsible for converting sugar to alcohol are critically important to enjoying a finished glass of beer. As the brewing industry has grown the number of available strains through yeast providers has grown and best practices have emerged.
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Sour has become a catchall word for a variety of beers, including what many breweries call “mixed-fermentation.” As the United States nears 10,000 breweries, finding a way to stand out has become both critically important and increasingly difficult. Cultivating a house yeast culture or experimenting with different yeast strains are ways to create beers that are uniquely yours.
Matt Manthe of Odd Breed Wild Ales shares his thoughts on creating a culture that reveals wonderful expressions:
“One thing that really interests me, especially in the last couple years or so, is working on different ways to manipulate our mixed culture to produce different types of flavors. When I first started dabbling with them, I was basically running a rudimentary yeast lab that I put together in an extra room, and I was managing multiple different blends.
by Christopher White
Most brewery fermentations are carried out with reused yeast, but the question of how to store and maintain it frustrates even the most skilled brewers. It actually is not as difficult as some believe, and there are techniques that brewers can use to significantly lengthen the life span of their yeast.
The fact that we can take a byproduct of beer production – yeast – save it, and reuse it in successive fermentations is quite unique. We can do this because yeast is still alive and healthy after most beer fermentations. The low alcohol level in beer prevents the yeast from dying, as yeast does in wine production. The problem for most brewers, then, is not whether to reuse yeast but how to store it and keep it healthy for future brewing sessions.
By Sylvie Van Zandycke, PhD, Lallemand Brewing
History and characteristics of brewer’s yeast
The yeast Saccharomyces cerevisiae was used for thousands of years in the fermentation of alcoholic beverages before anyone realized it! The Dutch scientist, Anton Van Leeuwenhoek observed the mighty cells for the first time under the microscope in 1680.
by Jamie Martin, Brewmaster, Dells Brewing Co.
Aerating yeast – I stumbled upon this by process accident one day when I was short on oxygen. First I transfer my yeast into the fermenter along with two to three gallons of whatever beer the yeast came from. The result is a yeast slurry that is very loose and wet. Next I bubble oxygen in from the bottom of the tank at 5PSI for 15 minutes. The yeast gets all the oxygen it needs and I am not adding oxygen to my wort that could cause stalling. The key to this process is the addition of the beer/wort to the yeast so it is loose.
Using yeast as yeast nutrient – Happy healthy yeast already has all the nutrients it needs, so on a brew day instead of using a commercial yeast nutrient you can pull some yeast (I use 100ml/BBL), and add it to the boil. The cell walls will break down and the nutrients will be added to your wort.
The main purpose of the fermentation is to allow the yeast to convert the sugars from the wort into alcohol. Other yeast byproducts are also produced as a result of normal cell functions of survival and growth. These include fusel alcohols, esters and aldehydes which will determine the character of the beer. The different flavors are influenced mostly by the yeast strain but also by fermentation parameters (temperature, pressure, pitching rate etc…). From that point of view, trials are key to finding your perfect and unique product! Towards the end of the fermentation, the yeast will start to flocculate and accumulate at the bottom of the fermenter, even for ale strains if the fermentation is performed in a cylindro-conical vessel. This phenomenon will help greatly the clarification process of the beer. The yeast should not sit in the cone for long periods as it will likely deteriorate very quickly due to the stress imposed by the brew (alcohol, pressure etc…). If it cannot be re-used straight away, it should be stored appropriately (see section on yeast storage).
The situation is different for ale strains in open fermenters where the yeast will accumulate at the top of the vessel and should be skimmed off. When skimming yeast, the aim is to remove the yeast head at a point in the fermentation process when it is still sufficiently active and to leave just enough yeast in suspension to complete the fermentation process and form a thin but stable protective cover over the surface of the beer. If the yeast is allowed to remain on the surface of the beer until the end of fermentation autolysis may occur due to overheating. This will result in byproducts from the yeast being released and decreased viability may impact on subsequent fermentations. Additionally, the longer the yeast head is kept at ambient temperature, exposed to the air, the greater the possibility of aerial infection.
Nutrients – The use of nutrients or ‘yeast food’ can increase fermentation performance without impacting on the flavor profile. Nutrient addition is particularly recommended for high gravity or high adjunct brews to avoid stuck/sluggish fermentations and production of off-flavors. Essential nutrients are FAN (Free Amino Acids), vitamins, minerals, sterols, fatty acids, phosphorus etc… There are several products on the market which differ greatly in their composition. Knowledge of wort composition and nutrient deficiency is useful in order to choose a particular nutrient product otherwise trials are recommended. Zinc addition is known to improve fermentation performance even in non-deficient worts. Addition of zinc-enriched yeast (Servomyces) has been proven more efficient than mineral zinc.
Contamination affects the quality of the beer. Most contaminants will produce off-flavors, acids and non-desirable aromas. They can also produce hazy beers and films. They may compete with the production strain for essential nutrients; they can also induce stuck fermentation or over-attenuated beers. There are two major groups of microorganisms responsible for contaminating wort and beer: 1) Wild Yeast and 2) Bacteria.
1) Wild yeasts – Not all yeast are desirable in a brewing fermentation ‘wild yeast’ are usually defined as: ‘any yeast which is not deliberately used and under full control’. Wild yeast contamination can occur if the pitching/cropping yeast is in contact with air and anything added in the fermenter is a potential source of contamination. Hygiene is key. Wild yeasts are not killed by acid washing and therefore production yeast contaminated with wild yeast needs to be discarded to avoid product defect. Wild yeast infection can result in hazy beers, off-flavors production, decrease production of ethanol and rate of attenuation, superattenuation. They can also cause aberrant flocculation; they tend to stay in suspension and do not interact well with finings. Wild yeast can either be of the Saccharomyces or non-Saccharomyces genus.
Saccharomyces wild yeast
Cross-contamination with another S. cerevisiae strain can cause flavor defects as well as unusual fermentation performance. The most troublesome Saccharomyces wild yeast is Saccharomyces diastaticus. This particular yeast has the ability to break down the dextrins which are not being used by S. cerevisiae strains resulting in overattenuated beers. Saccharomyces wild yeasts are facultative anaerobes.
Adjunct: unmalted grains (corn, rice, oats etc…) used in brewing to supplement the main mash ingredients (malted barley). Can be used to create different types of beer or to cut cost on using less barley malt.
Autolysis: also called self-lysis, refers to the rupturing of the yeast cell and subsequent release of yeast intracellular components into the beer (mostly off-flavors). Autolysis mostly occur when yeast is subjected to stress or temperature shock.
Biofilm: complex aggregation of microorganisms marked by the excretion of a protective and adhesive matrix. Cropping: refers to the removal of the yeast which has settled to the bottom of the fermenter at the end of the fermentation. Cropped yeast can either be discarded, stored or re-used straight away.