Yeast starters are an easy way to take your brewing to the next step. In my experience, most advanced brewers either build a yeast starter or pitch multiple packages of yeast to obtain the proper cell counts per milliliter of wort. So why do we make yeast starters?
1. A reduction of lag time between pitching and the start of fermentation.
2. The flavor impact that the yeast add to the beer is affected by number of cells and the their health
For more on the science of yeast starters, Kettle to Keg carries a number of books on the subject as well as all the equipment you will need to make your own.
How To Make A Starter
Needed Equipment: Erlenmeyer flask (or other vessel that can be washed and sanitized), 4 oz (113 grams) DME, Yeast nutrient, Sanitizer, Non-reactive pot, Measuring cup, Funnel
There are two paths to take in one you mix and boil the dry malt extract and water in the Erlenmeyer flask on the stove. The flask must be borosilicate glass, which is able to handle rapid shifts in tempreature with out shattering (this is the only type kettle to keg sells). The other path is to boil and cool in a separate pot and then transfer to the vessel that you will ferment your starter in. The pictures included in this post show a hybridization of both paths.
After you have cleaned and sanitized anything that will touch the wort once it has been cooled, measure out:
4 oz (113 grams) of dry malt extract.
800 ml’s of water
If you will be using the flask, put the water, DME and Yeast nutrient in it and put it on the stove and heat slowly to boiling.
If you are using the pot method add all the ingredients and boil, partially covering the pot for the last 5 minutes to sanitize the cover and protect the wort during the cooling stage.
The DME can take sometime to dissolve, you can help it along with a wisk and some stirring.
The boiling wort will look just like the boil when making a batch of beer (minus the hops) there will be hot break and you still risk boil overs and the subsequent mess. Have a small bowl of ice cubes to toss to stop the boil over before it happens.
Partially cover the pot to sanitize the lid which will help protect the wort while cooling in an ice bath (If you are using a flask cover the opening with a piece of sanitized aluminium foil). Cool the wort untill you get to pitching temp. If you pitch to high or to low you shock the yeast.
After the wort has reached the temperature that you want, pour the wort from your pot into the fermenting vessel and add a sanitized stir bar if using a stir plate. If not swirl the fermentor every few hours to keep the yeast in suspension.
These picture show the saved yeast (note the nice cream color on the left) Most of the clear beer was decanted and the sample was mixed and allowed to sit for ten minutes or so to allow for dead cells and any other trub to precipitate out and settle to the bottom of the jar. The slurry in suspension is then added to the fermentor to begin building the starter. In most cases you will pour a new package of liquid yeast into the fermenting vessel.