Saving yeast doesn't necessarily mean saving money.
I have just started making yeast starters for my brews. I like that I can continue to reuse the yeast I already have paid for. I am self admittedly cheap, so I am curious - after making a starter is it possible to store it long term? I have some left over London Ale yeast sitting in my fridge . . . how long will that last? If I make a yeast starter, what could I do to make it last?
Reusing yeast is certainly one of those things that makes sense from a cost-savings perspective. Indeed, brewers have been harvesting yeast crops at the end of fermentation, temporarily storing the yeast and re-pitching it into subsequent batches for a very, very long time.
One thing that has been demonstrated through research is that brewing yeast is not something found in nature; mutations over thousands of years of brewing have resulted in yeast strains that are only found in breweries. This is really not too different from domesticated animals. Another thing that is known about brewing yeast is that some of the properties strains are selected for by brewers change with subsequent generations. One example is a yeast strain’s flocculation characteristic; lager yeasts, in particular, tend to become less flocculent if the yeast is used for too many generations. Some strains change faster than others, but as a general rule most breweries do not continue to reuse yeast indefinitely and new yeast is brought into the brewery by growing cells from some sort of storage form (liquid nitrogen, freeze dried samples or cultures stored on a growth medium).
The best yeast to reuse comes from a healthy and normal fermentation. Batches that do not ferment normally, or those that have unusual aromas, are not top candidates for cropping. Assuming that you have a batch that is a good candidate for yeast cropping, you need to determine how to harvest the yeast. Most yeast strains, including most ale yeast, will eventually settle to the bottom of the fermenter within a few days following the end of fermentation. I think the easiest way to harvest yeast at home is to rack the beer out of the primary, swirl the yeast up from the bottom of the fermenter and pour it into a clean and sanitized storage container. Most thick slurries harvested in this manner contain about 750 million cells per milliliter.
It is best to store yeast in a vented container because there is a real possibility that the cropped culture will produce carbon dioxide. Do not store yeast in sealed glass containers as this may result in exploding glass containers. I am a proponent of using plugs of cotton batting to close the mouths of Erlenmeyer and Fernbach flasks.
Yeast cells have a finite storage life, and as energy reserves, such as glycogen, are consumed during storage, cells begin to die. The most common method used to extend the storage life of yeast cultures is to rapidly cool the yeast culture and store it somewhere around 32–38 °F (0–3 °C). Some brewers wash yeast with cold water after harvesting to dilute the beer content of the slurry since the alcohol content of beer is detrimental to cells during storage. Yeast can easily be stored for up to a week in this temperature range without losing too much viability in the culture. Anything greater than a week is too long for most commercial brewers because the economic risk of using old and tired yeast cultures is simply too great.
Things are not too different with homebrewing, except the risk of failure. If I am running a brewery that brews 100-barrel batches and ferments these batches in 400 barrel fermenters, the cost of a failed batch is equal to about 20 man hours of work plus about 20,000 pounds of malt and 200 pounds of hops; roughly $8,300 in labor and raw material costs.
At home the cost of failure is perhaps even greater. You spend your hard-earned free time and you pour your heart and soul into crafting that perfect batch of wort. If you want to re-use yeast at home, do not push the limits of storage time and expect anything miraculous to occur. In fact, you should actually expect poor results because that is what you could see.
How do I make specialty grains? I want to start buying 25 to 50 lbs. (11 to 23 kg) of grains to limit the cost of gas to and from my store. Is it possible for me to make specialty malts at home, and if so how do I go about doing it?
Specialty malts fall into a few basic categories defined by the method of production. Higher kilned malts generally include those types that have more color and flavor than pale malts and that are produced using the same type of malt kiln as the “standard” pale malts. Munich, biscuit, amber and Vienna malts are examples of types that are made in the kiln.
Crystal or caramel malts are stewed before drying, although not all maltsters use the term “crystal” and “caramel” in the same fashion. Sometimes the terms are interchangeable and the final cure phase may occur in the kiln or in a roasting drum. The process of stewing is similar to mashing, but the mash occurs within the malt kernel. Stewing is accomplished by heating green malt, that is, malt that has completed germination but is not yet dry, to between 140 and 175 °F (60 and 79 °C) in a closed vessel preventing the escape of moisture. Stewing converts starch into sugar and also increases the amino acid content by proteolysis.
After the stewing phase is complete the malt is kilned, where the final temperature used in kilning — often termed the cure temperature — and cure time is altered depending on the degree of color development desired. Crystal malts are often made in roasting drums because the stewing and kilning process is easier to control. An older method, rarely used today, was to begin with kilned malt and rehydrate the grain to achieve a moisture content of about 45%.
This was followed by stewing and kilning to produce
Roasted specialty grains include materials like chocolate, brown and roasted malt and roasted barley. These ingredients get their intense colors and flavors by using final cure temperatures up to 400 °F (200 °C) for times up to 90 minutes. Roasting drums are always used for these products and the roasting process is quickly terminated by using water sprays to “quench” the roasted materials before the roaster is emptied. One practical concern when producing highly roasted materials is avoiding fires.
Start out with high-kilned types, like those produced on a drying kiln. A convection oven is a great tool for making specialty malts because one of the key features of a commercial malt kiln is forced air. Without forced air you will have temperature gradients throughout the malt and will get inconsistent results from kernel to kernel. In addition to a convection oven, you will also need some sort of drying tray that you can load the malt into and place in the oven. You can make your own drying tray using a box frame and stainless steel screen mesh. Do not use any material that could be a fire hazard for the frame, however.
Crystal malts would be a natural next step to try. Adjusting the moisture content of dry malt can easily be estimated by simply adding a known weight of water to the malt you wish to rehydrate. The stewing process could be carried out in a covered stock pot in your oven. After the malt is stewed you can turn it out on your drying rack and begin the kilning process in your convection oven. Make sure you read up on kilning methods; the kilning temperature used to dry malt is lower than the cure temperature and maltsters often use a temperature profile to achieve even drying with minimal color-pick before the final cure temperature is met with the goal of producing color and flavor. As far as roasted grains are concerned, I would suggest buying those unless you have a small coffee roaster.