Dry Yeast

Dry yeasts are an extremely convenient way to make great beer, without all the work involved with most liquid yeasts. First of all, a yeast starter is not required, so the yeast can be prepped on the same day as brewing. Many brewers with busy schedules like this feature of dry yeasts mosts since they never really know when they will have time to brew, and liquid yeast requires several days of preparation. 15g of dry yeast provide a sufficent number of yeast cells to start an ale fermenting extremely quickly – in the right conditions usually only a couple of hours. For lagers use twice as much if cold-pitching.

There are some exceptional dry yeasts on the market today, including those from Danstar/Lallemand, and DCL in the UK. As mentioned, pitching dry yeast directly into the fermenter will produce good beer in most circumstances, but there are much better ways to do things that will help your beer.

Rehydration

The easiest way to improve conditions for your yeast is simply to rehydrate it. To do this, sanatize a 500ml (1 pint) jar, and fill it 3/4 of the way with water that has been boiled and cooled. Do not use distilled or deionized water since the yeast actually needs some of the minerals that are in regular tap water. Simply boil a Mason jar for about 5 minutes, then remove the jar with a pair of canning tongs, taking about 350 or 400ml of the boiled water with it. Then just put the lid on the jar, and allow it to cool to 40C (100F). Once cooled, simply stir your dried yeast packet into the water, and allow to set for 1/2 hour before using. You should take a few minutes to read what the folks at Danstar/Lallemand say about rehydrating dry yeast, and just how important it is. Note they state that rehydration is best of the yeast at 40C/100F.

Liquid Yeast

The next step up from rehydrating your yeast is, of course, the use of pure liquid yeast cultures. This won’t neccessarily result in better beer, as there are definitely good quality dry yeasts on the market. Two decades ago it was true that dry yeast was produced in a less sanitary environment than liquid, and therefore there was a greater risk of infection when using it, but significant advancements have been made in that time and risk is about equal now with both (liquid is still slightly more sanitary, but only by a very tiny amount). The main advantage of liquid yeast is that it gives the homebrewer a much wider variety of choices. It is without question that the yeast strain used has a huge affect on the final flavour and overall characteristics of the beer. Should the beer finish malty and sweet, or dry and crisp? The yeast used can have a major affect on these things. Although newcomer DCL now has a very good selection of dry yeasts on the market including some real dry lager yeasts, there is still a greater variety of liquid yeast out there. And a variety of yeast is yet another tool which allows the homebrewer to fine-tune a beer to his or her own personal tastes.

The best known brands of liquid yeast are from Wyeast, White Labs, and Brewtek, although there are others available. Another good source for a quality liquid yeast is your friendly neighbourhood Brewpub or Micro-Brewery. Most brewmasters will allow you to come with your own mason jar which they will gladly fill up for you. Even your local University or research station may be a good source of liquid yet – check the Biology department.

Pure liquid yeast strains usually come either in a testtube-like package, or in a large-ish foil “smack-pack” (as they are called in the vernacular). Although the manufacturers’ instructions clearly state that the yeast from these packages can be pitched directly into 5 gallons of beer wort, experts agree that far better results are obtained if the yeast is first stepped-up in volume by means of a starter. Personally, we’ve had reasonable results without using a starter, but have found that with the use of a starter, the beer begins fermenting much more quickly, and finishes sooner as well. So instead of it taking 24 to 48 hours for your beer to start fermenting, with the use of a starter it should only take 2 to 6 hours. This shorter lag time translates directly into a lesser chance of an infection spoiling your beer, since it allows your brewers yeast to take control of the wort and force out any other organisms which may be trying to take hold. Note as well that when brewing true lagers (that will be fermented at low temperatures for long periods of time), it is essential to use a starter. In fact, an extremely large starter should be used – 3 times what is used when brewing ale.

In the last few years several of the major yeast manufacturers have introduced what they call “pitchable” yeast, which is a package of yeast that contains significantly more yeast cells than the smaller packages. For example, Chris White of White Labs once told me that his pitchable vials of yeast contain about 70% of optimal yeast cell count, whereas regular liquid yeasts contain only a small fraction of that which is why they must be stepped up by means of a starter.

Washing Yeast

For reasons of economy and convenience, many homebrewers like to reuse the yeast from the fermenter. One key benefit in doing this is that a great deal of this so-called ‘slurry’ can be collected, and only a portion of that collected (1/4 to 1/2 cup) is required to provide a fast start and strong, healthy fermentation for the next batch. Although the sediment from the fermenter can be collected as-is and stored for several weeks before being successfully reused, there can be a lot of non-yeast material especially if the sediment was collected from the primary fermenter. In this case there is also a lot of protein from the hot and cold break, as well as some hop material especially if pellets were used. So the brewer may want to consider a simple yeast wash to improve the health of their yeast, enabling them to store it for up to 2 or 3 months with no problems.

We originally learned to do this from the instructions given on the Wyeast homepage, but have altered the technique a fair bit to suit our own tastes. Our version of yeast washing goes like this :

  • boil and cool about 2 quarts/litres of water, and clean and sanitize a couple of quart/litre mason jars. You can kill two birds with one stone by boiling the jars in the water. You may not use all this water but better to have too much than too little
  • Sanitize the rim of your fermenter. Alcohol, iodophor and star san are best as chlorine may not be a good idea since you cannot easily rinse the rim
  • Swirl the fermenter to rouse all the yeast you can from the bottom. If the yeast is really packed you may have to add up to 500ml / 1 pint of your boiled water to the fermenter in order to swirl it all off the bottom
  • swish and swirl! to rouse everything
  • dump the sediment out into one of the jars, or if you think that may be too difficult a target to hit, pour it into a sanitzed saucepan first, then fill your jar from there
  • put the lid on securely and gently shake the jar and you should notice material separation yeast should go into suspension, and the stuff you do not want should start to settle out
  • you may have to shake and let settle a few times over a few minutes
  • once you get separation and the gunk has settled out on the bottom of the jar, pour as much of the liquid from the top as you can into the 2nd jar, leaving as much of the sediment behind as possible
  • top up the 2nd jar with your boiled and cooled water
  • shake it again to see if you can get it to separate again. Meanwhile rinse and sanitize the first jar
  • if you get separation a second time, pour back into the first jar again, leaving the sediment behind
  • put the lid on, and store in fridge for up to a couple months

One of my additions when I’m feeling ‘fancy’ is that I will do an acid wash by carefully adjusting the pH of each jar down to 4.0, which will help kill a lot of wild yeasts and bacteria. But that’s a fair bit of effort and I’m lazy, and I’ve never had problems when I do not do it this way.

When it comes time to use your saved slurry, the yeast will have all settled to the bottom of the jar. Pour the liquid off the top and then add 500ml / 1 pint of starter wort to the jar to start it. This wakes the yeast back up and gets it ready to ferment your beer for you. This can be done on brew day morning.

Making a Yeast Starter

There are several very good reasons why one would want to make a starter for one’s yeast, rather than just pitch the smack pack or slant directly into the wort. First and foremost, there are not enough yeast cells in either of these to allow for a rapid fermentation. An adequate number of cells allows the yeast to take control of the fermenting wort and kill off any other competing organisms which invariably get into the wort even if you follow the most rigorous sanitation regime. Only a high initial population of viable yeast cells will ensure a quick start, and a rapid fermentation. Also, it is a known fact that yeast react differently according to how much sugar is available to them. Too little or too much and they don’t work as well.

Therefore, instead of dumping a small amount of liquid yeast into a huge carboy, the best way to start your yeast is to step it up by means of incremental starters. This allows the brewer to gradually build up a large yeast population (ahead of time, of course) for pitching into the beer wort. There are varying opinions on just what volumes should be used at the different stages, but there is little argument that stepping up is better for your yeast, and thus better for your beer.

The best wort to use for yeast starters is a 1.040 SG wort with or without hops, depending upon whom you listen to. Those who say not to use them argue what if you use a good British hop for your starter wort, and then want to use it to start a yeast for beer which gets brewed with a significantly different hop. That could potentially be noticable depending on a number of facters. This is only really a potential problem if you can your own starters, which will generally be done weeks if not months in advance. However, if you make your starter wort on-demand you can use the same hops in it that you plan to brew with. The good thing about using hops in your starter is precisely their anticeptic properties which will help fend off any potential infections in the starter culture.

We make a can wort ahead of time with 500g (1 lb) of dry malt extract boiled in 4 litres (1 gallon) of water. We then pressure-can the wort in various-sized mason jars, for quick-and-easy use whenever we want it. A good general-purpose high-alpha hop in low amounts (5 HBU or 10-15 IBU). We use Hallertauer for our starters since we tend to brew Continental style beers in which they fit. But realistically the small amount of starter in a batch will hardly make a difference, and I challenge just about anyone who says they could pick it out.

NOTE: it is extremely important that you pressure-can the wort! A lot of homebrewers disagree here, but any professional canner will tell you that unless you pressure-can the wort, there is a chance of becoming seriously ill, or even dying. If you want to make up a smaller amount, use 45ml to 75ml (3 to 5 tablespoons) of dry malt extract for every 250ml (1 cup) of water.

Homebrewers begin their starters from one of two packages : either a commercial package (vial or smack pack), or from a home-cultured slant (either a vial or tiny mason jar).

If starting from a commercial package, smack the package and allow it to swell. This will take 1 to 5 days, depending upon the age of the package. After it has swollen, you may want to consider culturing some for your own yeast bank. Once you have taken your syringe full of yeast (taken before the package has been opened, for maximum sanitation) from the package for your yeast bank, pitch the rest of the package into cleaned and sanitized bottle or jar which contains 250ml of well-aerated SG 1.040 wort, affix a cleaned and sanitized bung and airlock to the vessel, and allow it to ferment-out until the yeast is sedimented on the bottom. If starting from a home-cultured slant, simply start the slant in 100ml of SG 1.040 wort and allow it to ferment-out in the same manner. In either case, the yeast package should be allowed to come to room temperature before opening, so as not to shock the yeast inside.

A lot of newbies make their starters and when they see no activity the next day they begin to panick and see help. Usually everything is just fine, and they have simply missed all the action. Since a starter is so much smaller than a full batch of beer, it will usually completely ferment-out in a couple of hours or so, often while the brewer is sleeping. Do not panick. If there is some white sediment at the bottom of your starter jar, you are fine. You probably just missed the action.

When the initial amount of wort has sedimented out, carefully pour out (and discard) half to three-quarters of the starter (since most of the yeast is now on the bottom), then add another 500ml of well-aerated wort. This step can be repeated as much as you like, however, excellent results can be obtained for ales with a total of 3 additions of 500ml each. For lagers you want to use about twice that amount.

When it comes time to add the slurry (the sediment), you can dump off 3/4 of the liquid once again and just add the slurry, or you can do this early in the morning on brew day so as to add an actively fermenting starter later on in the day. The latter is probably better, although superb results can be obtained by pitching nothing but slurry, even in a lager.

The most important thing to remember when feeding your yeast is relax, don’t worry about it. If there is an obvious heavy sediment in the bottom of your starter vessel, then just feed it some more. If you feed it a 5 or 6 hours too early, or too late, it’s no big deal. Just make sure that it is well sedimented when it comes time to use the starter.

When the time comes to use your starter, just carefully pour out and discard most (2/3 to 3/4) of the liquid from the top, swirl the container to completely rouse the sediment back into suspension, and pitch it into your carboy or into your proofing wort early on brew day. In most cases you’ll then see active fermentation within 2 to 4 hours, even if only using the slurry. If it takes more than 24 hours you probably did not have a sufficient amount of slurry and should ramp it up next time. As long as the beer starts within 48 hours you are fine, though.

If for some reason you cannot brew after you’ve taken all this time and trouble to make your starter, the entire starter can simply be put into the fridge and stored for several weeks. Then before brewing, take the jar out of the fridge to allow to come to room temp, we dump out the top 3/4 of the liquid, rouse the remaining sediment, and feed it another 500ml of wort. This will wake up the yeast and get it ready and raring to go.

If the slurry is starting to become the colour of peanut-butter, it is time to toss it out and start again from scratch.