Saturday, January 12, 2008

Yeast Starters

The more I read up on home brewing, the more I get fascinated with the science and biology of the process. One aspect that I find interesting is the yeast. These little animals are extremely important to the overall brewing process and are probably the most mysterious part of the process too.

When first starting out, a lot of kits use dry yeast. After the brew, the directions usually say to sprinkle the yeast on top of the wort. This works fine, though it often takes time for the yeast to rehydrate, start reproducing, then start fermenting. Some people believe that dried yeast just doesn’t add to the complexity in taste that live yeast does. One thing is true though, there are many more varieties of liquid yeast then there are dry yeast.

Using liquid yeast usually helps in the quickening of the process from cooled wort to fermentation. That is a crucial time in home brewing, a time when things can go wrong. The quicker the yeast start doing their jobs, the less chance of contamination to occur.

For most average gravity brewing styles, a single White Labs tube or Wyeast smack pack of yeast is enough for a 5 gallon batch. When creating a high gravity or lager beer, it is best to help the wort out by pitching additional yeast. This can be done by purchasing multiple tubes or you can create a yeast starter that can turn one tube into the amount you need. Since my next brew is going to be a double IPA with a starting gravity of about 1.070+, I decided to create a yeast starter.

I purchased a 1000ml yeast starter kit from It was pretty cheap, only $12. The kit included a 1000ml Erlenmeyer flask, 1/2 pound of dried malt extract (DME 10), and 1oz of yeast nutrients. The process is pretty simple.

I first mixed in 1 cup of DME 10 and a pinch of nutrient with about 800ml of Brita filtered water. I placed the Erlenmeyer flask on the stove and brought it up to a boil for 15 minutes. I boiled in the beaker cause it seemed like a cool idea and it brought me back to my high school days. Though, it has it’s issues. Since the flask gets extremely narrow up at the top, the littlest boil over would go shooting up and over. This would happen so quick that it was hard to catch. It only happened one major time, I would recommend using a small sauce pan and then funneling in the cooled wort into the flask after. And on another note, you don’t need a flask at all. An old sanitized mayo jar would work too, though they are glass and if you pour pour hot wort or cooling hot wort in it, the glass may crack. It is best to always use cooled wort if using regular glass. Since I boiled in the Erlenmeyer flask, i just took the flask and put it in an ice bath in the sink. 5 minutes later, it was pitching temperature.

With my order from, I also bought a Oxygen system to get the most out of my wort. The system came with a regulator, some tubing, and a stainless steal air stone. The oxygen had to be purchased separately, so I had to run out to the local Lowes Hardware Store and purchase a disposable can of BernzoMatic Oxygen for about $8. After sanitizing everything, I stuck the air stone in the wort and turned the knob to the gas. Billions of the tiniest bubbles came out and created a Guinness style draft head on the wort. Adding Oxygen will greatly help the yeast grow and reproduce. Since I don’t own a stir plate yet, I would just swish it around every so often to help keep in oxygenated.

I plan on brewing my Blind Pig Double IPA clone tomorrow and I now have a healthy amount of yeast to pitch. By looking at the flask, I think I have about 3-4 times the amount I started with. I plan on sticking the flask in the refrigerator tonight to have the rest of the active yeast fall to the bottom of the flask. Then I will siphon or pour off some of the spent wort. This way I don’t contribute to off flavors by adding different wort to my IPA wort. Most people just throw it all in, but I don’t want to get any off flavors by using a different style wort. I could have always made 1000ml version of the double IPA and pitched it directly in, but that will be later on in my home brewing career. This was my first starter and I think it turned out great.