Our brewers yeast is propagated using advanced aeration/agitation technology and RBY’s specially formulated and fortified “Super Wort”.
Performance is unparalleled with vigorous fermentation the rule rather than the exception. Yeast for five gallon batches are sold in 30 ml vials. One barrel (32 gallon) batches are sold in 200 ml bottles. We grow brewery scale custom pitchable batches as well.
|Source||Sierra Nevada PA|
|Fermentation Temp (F)||65-75|
|Tasting Notes||Neutral all purpose, clean crisp. Hint of apple above 75F|
|Fermentation Temp (F)||65-72|
|Tasting Notes||Powdery, slight fruit and sulphur|
|Fermentation Temp (F)||64-72|
|Tasting Notes||Dry and neutral with plumb and raisin notes.|
|Fermentation Temp (F)||64-85|
|Tasting Notes||Banana, clove, bubble gum, spice, apple. Neutral compared to other Belgian strains|
Whether you are brewing 5 gallons or 500 barrels, the number of living yeast cells introduced at pitching is critical for proper fermentation performance. Every wort, fermenter, oxygenation system, and yeast strain is different, so most brewers agree that “hitting it out of the park” is best way to avoid incomplete fermentations. The number of living cells/ml in a liquid starter culture is determined by RBY labs and is shown on each label. RBY labs suggests over 100 billion cells/5 gallons for low gravity fermentations, and over 200 billion cells/5 gallons for gravities higher than 1.060. This translates to 5 million cells per ml for low gravity worts under 5% ABV, and 10 million cells per ml for higher gravity beers.
If pitched at a low rate, yeast cells spend too much energy dividing, and can flocculate out early. If pitched at a higher rate, the yeast directs more energy toward turning over the carbohydrates and nutrients in the wort, and making the desired CO2 and ethanol instead of dividing. The transition between aerobic and anerobic fermentation takes time and energy. Also, oxygen is required for essential sterols and unsaturated fatty acids required for alcohol tolerance. That is why shaking or oxygenation of wort prior to pitching works so well because it buys more aerobic energy before the yeast start transitioning to the anaerobic state.
If you have problems controlling fermentation conditions (especially temperature), oxygen, or supplement your brewing with simple sugars, use more yeast to be safe. If in doubt, buy 2-3 RBY 5 gallon pitches for each five gallons to ensure proper yeast performance.
Problems with beer spoilage have occurred since the dawn of fermentation. Those problems have spurred many inventions, including stainless steel fermenters, addition of hops to retard lactic acid bacterial growth and the accidental invention of cold fermenting lager yeast that grow in conditions too cold for most spoilage organisms.
In leu of these technological improvements, most brewers have run into a case where “bottle bombs" or "gushers" form months after a thoroughly finished and dry beer has been bottled. Other times bottles go sour months after bottling. I’ve tasted kegs from breweries lately that have the distinctive horse blanket/sour from Brettanomyces in an IPA made with only Chico Saccharomyces yeast.
How does this happen? It’s the dreaded “C” word or contamination. Where does it come from? Since most modern fermentations are closed to air, the short answer is: dirty surfaces with living microbes or viable spores somewhere in the brewing process. Wort can be considered a wound up spring full of potential energy. There are many microbes other than brewers yeast ready and willing to unwind the energy to reproduce and spoil your beer! Contamination can have a devastating effect on cash flow.
Properly pitched yeast in combination with hops probably squashes most beer spoilage organisms due to rapid formation of alcohol and pH drop. But, even a few strong survive, they will raise their ugly heads later when they find their niche, and unfortunately may end up in customer’s hands (yikes). I’ve seen a trend where breweries are serving beer that didn’t make it and calling them sours. I’ve seen their books go sour as well. Only purposely inoculated sours should be served.
Keeping things clean
Homebrewing is easy if all surfaces and the inside of hoses and pumps are cleaned with 180oF detergent with a high pH and physical scrubbing with brushes, and a sanitation step with an oxidizer like iodine or an acid detergent like Star San.
But, as homebrewers progress to professional brewing, homebrewers have a tendency to think that homebrew sanitation is sufficient for large brewing systems. Professional brewers use a technique call CIP or Clean In Place. This requires much more powerful chemicals to first lyse cell membranes on the surface of stainless and hoses using a spray ball and hydrostatic pressure recirculation in 180o F, 0.2% (0.05M) to 2.0% (0.5M) sodium hydroxide or “caustic”. In this cleaning step, caustic causes fat component of membranes to be broken down into glycerol and free fatty acids. After a good recirculation cleaning step with caustic that includes every nook and cranny, no membranes should be intact on any surface. Every surface that comes in contact with wort cooler than boiling must be cleaned. Especially problematic are pump heads, heat exchanger plates and hoses where biofilms are formed. Even the hot side should be cleaned with a least caustic.
PBW and other detergents don’t have caustic to lyse membranes, and I am surprised how many professional brewers clean in place with a homebrew reagent.
Next, after the cleaning step with caustic, the equipment must be sanitized with an acid based oxidizer. This takes care of any spore formers that have rugged outer cell wall components that may be resistant to caustic. Oxidizers trash proteins and biomolecules, and cause cells to pop open. This reaction can be completed at room temperature. The best sanitizer according to most experts is peracetic acid or PAA. PAA breaks down into acetic acid after the peroxide is reduced by a target molecule such as a membrane or spore coat protein. 75 ppm (mg/L) PAA kills 100% of target organisms in 30 seconds. The low pH causes stainless to passivate and form the antimicrobial chromium oxide layer. Low pH also dissolves calcium deposits or "beer stone”.
Further, professional brewers can monitor the CIP regimen by swabbing surfaces and plating on petri plates. Beer should be assayed for microbial contamination to check for contamination. This subject will be cover in the next article.
Using these cleaning and sanitizing agents properly and performing qc assays on equipment and beer, the brewer can gain confidence that no other organisms are growing in product batch after batch.
Fermenting Raw Julian Apples with a Belgian Strain
Evin, the head brewer of Cismontane Brewery in Orange County, CA came into Real Brewers Yeast Labs with a growler of delicious unpasteurized fresh-squeezed cider from Julian, CA. He wanted us to test if RBY “The Monk” Belgian ale strain would make his unfermented juice into a wonderful hard cider. I measured the gravity, about 10 Plato (P). I figured I needed at least 0.5 million cells/ml/degree Plato (P) in a normal 10 P wort or 5 million cells/ml pitching rate. But this was not wort, it was hanging on a tree a few days before. No added nitrogen, Mg Zn, Ca, etc. The yeast would starve! In addition the pH was 4.5 well lower than the pH 5.7 of standard wort. I really didn't want to change the flavor of this sweet pristine juice with nutrient. What do I do?
This is a difficult fermentation. Since yeast is made up of all this stuff... Nitrogen from proteins and DNA, divalent cations, and biotin and thiamine, I decided to just add extra yeast. The pitching rate was 8 times the normal level at 40 million/ml. Presumably, the yeast will slowly autolyse releasing precious nutrients. A week later it was about 50% attenuated, but still clean tasting. Like most brewers and yeast propagators, I moved onto other projects like building my new 1000 L bioreactor. Two months later, I decided to check up on the concoction. The taste was wonderful, dry with slight phenolic clove nose from The Monk with an alcohol and slight apple ester backbone. The hard cider cleared and had a similar mouth feel of a fine Chardonnay. This was the best cider that I've ever tasted. Realistically most beer fermentations should reach terminal gravity in less than a week, and The Monk spanks out a 7% beer in 3-5 days when properly pitched at 80oF and 15 million cells/ml in a two row-malt background. All the nutrients are there from the all grain mash although I like to add Zn and Ca. Beer yeast are made for brewing beer, not cider... But boy they taste good. For barley based malts, the pitch rate rule is 0.5 million cells/ml/P up to 10P with a 95%+ viable pitch in wort. Freshly grown yeast is the rule. When beers reach above 10 P but below 15 P, the rule is 1 million cells/ml/P. after 15 P, things get dicy. Depending on the alcohol tolerance of the strain, more yeast is required to get past the 5% alcohol barrier that sticks underpitched ale strains. We like 1.5 million cells/ml/P above 15 P. 20 million cells/ml pitching rate is a great place to start for a beer above 7%. When corn sugar or dextrose is added, even more yeast should be added (2.5 million cells/ml/P). Some strains hate glucose, some hate sucrose, so we choose to leave out adjuncts. Dextrose puts the brakes on all sugar metabolism, so cells slow down and suffer through the anchor put on metabolism. When 5% alcohol is reached, some strains stick due to a glucose-induced metabolic train wreck. We find that 8x over pitching and added nutrient is great for making strong meads and distilling in corn based backbones with brewers yeast. Beer yeasts were not evolved throughout the centuries to make cider and distillates, but they have a extremely and uniquely smooth profile lacking obnoxious fusels from wine and whiskey yeasts when babied with a high pitching rate, ample oxygen, and nutrients.
Pitching rate or final cell count , C2 = number of cells/ml when diluted in final volume of wort to be fermented. To determine final cell count C2, use the dilution equation C1 X V1 = C2 X V2, where C1 is the cell count shown on RBY yeast product label, V1 is the volume of slurry used, and V2 is final volume of wort. Convert to volumes to ml (10 barrels = 1,170,000 ml). Solve for C2. C2 = (C1 x V1)/V2. C2 should be between 5-10 million/ml for a 1.040 beer.
RBY's main focus is to team up with creative fermenters. By giving brewers a low price point, no fault money back guarantee on all first pitches, and unparalleled brewer to brewer service, RBY strives to both supply and consult with craft beer customers, and instill trust and confidence in working with fermentations.
We make yeast from barley malt. We don't add chemicals, buffers or odd carbon sources. The theory is that natural growth media will induce enzymes necessary for vigorous fermentation of barley-based wort. Cell counts are published on each bottle to ensure proper pitching rate. Our yeast health is the best in the business.
The art of brewing is combining non-living ingredients, and allowing those ingredients to ferment with living organisms. Because we are constantly brewing, RBY is intimately familiar with what makes fermentations "tick", which is marrying the physical fermentation parameters with the genetics of the fermenting organism. RBY has over 70 working strains to choose from, and we are constantly isolating and breeding new yeast and bacterial strains. The idea is make our customers the best, most artistic fermenters in the world.