Beer Yeasts
Yeast is a eukaryotic micro-organisms classified in the kingdom Fungi, with 1,500 species currently described. An estimate of only 1% of all fungal species.
The species Saccharomyces cerevisiae converts carbohydrates to carbon dioxide and alcohols - for thousands of years the carbon dioxide has been used in alcoholic bererages.
How long does the fermentation take to complete?
Most fermentations will be complete within 14 days. Lager fermentions can take up to one month, plus aging time. The typical ale profile is to ferment very actively for 1-4 days, which is called the "exponential" or "log" phase. Then the yeast enters a stationary phase, which helps to mature the beer and can last from 3-10 days. The beer should be ready to bottle at this time. It is important to check the final gravity (FG), and calculate the percentage attenuation to make sure the fermentation is complete. If the particular yeast strain is not very flocculent, it is hard to gauge when fermentation is complete without calculating attenuation %.
What is yeast nutrient?
Yeast Nutrient is a complex blend of nitrogen, vitamins, and co-factors. It is designed to increase vitality and viability in the yeast propagations. This increases the rate of metabolism, which results in faster fermentation and greater yeast viability. It is an affordable way to increase the success of your brew. Our brewers have found it very beneficial for first generation, stuck fermentation and high gravity beers. Yeast nutrient can also be helpful when brewing high gravity beers. Nutrient is good for every generation and a must for beers above 1.070 SG or 17 Plato.
At what temperature should I pitch Ale yeast?
The yeast should be pitched at 70 to 75 degrees Fahrenheit, 21.1 to 23.9 Centigrade. Once you see active fermentation, bring the temperature to the desired fermentation temperature listed on the yeast package.
What temperature should I pitch a lager yeast?
There are two different methods of pitching lagers. Brewers use each method with success, but every brewer has their preference. The easiest method is (A).
A) Start the yeast warm and lower to 50-55F after the start of fermentation. The yeast should be pitched at 70 to 75 degrees Fahrenheit. Once you see active fermentation, bring the temperature of the wort down 10 degrees per 12 hours until the desired fermentation temperature has been achieved. This method works well without forming high amounts of esters because most esters are produced after the first 12 hours.
B) Pitch the yeast at the desired fermentation temperature (48-55 Degrees F). Lager yeast ferment well at this temperature, but they grow very slowly. If you are using this method, understand that you may not see signs of activity for 48-72 hours. If starting the fermentation cold, we recommend you make a 1-2 liter starter per 5 gallons, or a starter 10% of the batch size.
Why should I use liquid yeast as opposed to dry yeast?
Purity and variety of liquid cultures. Currently, dry yeast contains some level of contamination because the drying technology is not available to create a sterile product. There is more variety with liquid yeast because only certain strains of yeast can be dried. Even if they could be dried, most yeast strains do not have the demand to make a large batch of dry yeast economically viable. An increased variety of liquid stains also gives the brewer the flexibility to produce many different beer styles.
What is meant by pitchable quantities?
White Labs and Wyeast yeast have a concentrated cell count which does not require any additional propagation time. Therefore, vials can be directly pitched into a five-gallon batch of wort, giving you approximately a 5-15 hour lag time.
Why is the fermentation not starting in the recommended time?
The most common causes are oxygen limitation and temperature. Low dissolved oxygen levels may cause a long lag at the start of fermentation. Oxygen is a primary element needed for yeast to be able to produce cell walls. Temperature of the wort when the yeast is pitched is also critical. If the wort is above 85-90°F, this may decrease the cell viability. If the wort is too cold it can cause the yeast to slow down, therefore increasing the overall time needed for fermentation to start.
What is the lowest temperature I can ferment ale at?
Ale strains are most commonly fermented between 68 and 72 degrees Fahrenheit. It is not recommended that you try and ferment ale below 65 degrees Fahrenheit. The ale strains have much harder time fermenting wort at the lower temperatures.
What is the lowest temperature I can ferment a lager?
Lager strains are most commonly fermented at 50 to 55 degrees Fahrenheit. At 45 degrees Fahrenheit the lager strains will slow down and fermentation may stop. There is some variation between strains so it is recommended to follow the temperature ranges on the vial or strain descriptions.
How can I increase the alcohol level in my beer?
Alcohol is a byproduct of the yeast cells consumption of the sugars in the wort. As the alcohol level rises in the wort, the fermentation begins to slow down. Adding yeast nutrients to the wort can give the yeast new food allowing for an extended fermentation period. Yeast nutrient also helps to create stronger cell walls, which make yeast less susceptible to alcohol death. Another way to increase the alcohol level in the beer is to add yeast with a higher alcohol tolerance towards the end of fermentation.
Why is my beer over-attenuating?
Over attenuation can occur from wild yeast contamination, or from a warm fermentation. Also, the mash profile creates different types of sugars, which the yeast consumes differently.
Why is my beer under-attenuating?
Low oxygen levels may be one of the primary reasons for under-attenuation. Another factor could be under pitching. If an insufficient amount of yeast is added to wort, than you should expect a much longer fermentation time.
Why does my beer have a high ester and/or sulfur level?
High ester and sulfur levels are most commonly associated with high fermentation temperatures. Different types of strains also produce different ester and sulfur attributes. Make sure you choose the proper yeast for the style of beer you are making and ferment the wort within the recommended temperature ranges.
Can I combine yeast strains?
Yes, some brewers like to combine strains for more unique flavor profiles.
Will there be any benefits or drawbacks from this?
Some of the benefits of blending yeast strains would be to blend flavors or aromas of different strains. Over time one strain can dominate the other so the consistency of flavors would be lost over time. If flocculation is different between the strains, it is hard to collect an equal amount of each strain.
What is diacetyl?
Diacetyl is a natural byproduct of yeast. It is most commonly recognized as a butterscotch or buttered popcorn flavor in the beer. To minimize the diacetyl attributes in beer, it’s recommended that the fermenting wort rest once the beer has reached terminal gravity for 48 hours at 62-70 degrees prior to crashing the temperature. This stage allows to yeast to reabsorb the diacetyl.
What are anaerobic bacteria?
Anaerobic bacteria do not require oxygen to grow. In the brewery, the most common types of anaerobic bacteria are pediococcus and lactobacillus. Good cleaning practices and frequent testing are the best ways to avoid contamination in the brewery.
What are aerobic bacteria?
Aerobic bacteria require oxygen to grow. In the brewery, the most common types of aerobic bacteria are acetic acid and enterobacteriaceae. Good cleaning practices and frequent testing are the best ways to avoid contamination in the brewery.
Is overpitching yeast harmful?
If the beer is overpitched, yeast do not grow though a complete growth cycle. This results in few new yeast cells, which makes for unhealthy yeast and low viability by the end of fermentation.
Is it best to store yeast under beer?
Yes, the best way to store yeast is under finished beer. It is best to remove yeast from the fermentor because high pressure and heat that can affect yeast in a fermentor.
Is your yeast gluten free?
White Labs and Wyeast yeast are low in gluten and is below the European standard for being labeled as gluten free; the American standards are still being developed. The European standard for gluten free is below 20 ppm.
Yeast slurry in package: 12 ppm
When yeast is used with ingredients such as sorghum to make gluten free beer: 2 ppm
