Basic yeast questions

Question

I've been researching online for months now in preparation for my first brew but there are still questions to which I can find no answers.

1. Is yeast either dead or alive, i.e. works 100% or not at all, or can it deteriorate to a point in between? And is there a way to test its effectiveness before pitching?
2. How trustworthy are the unbranded little sachets that come with a single can kit? Would I be better using a brand of recognised quality?
3. Any advantage to 'starting' it with water and sugar before pitching?
4. Is it a good idea to add extra yeast to a kit brew as an insurance, or is too much as bad as not enough?
5. Do I need to add more yeast than comes with the kit if I add extra fermentables above the instructions? (for a higher ABV)
6. Does anyone add yeast nutrient to kit brews?

Answer 1

1. An individual yeast cell is either dead or alive. A packet of yeast will have millions to billions of cells though. Some percentage of that will be alive, and the remaining percentage will be dead. The older the packet, and the worse the storage conditions, the higher the percentage of dead yeast.

2. Depends on the brand of kit. Some kits use no-name yeast, for which I would spend the $0.99 on a pack of fresh, brand-name yeast. Some kits are popular, use good yeast, and don't sit on the shelf for very long. Those you can probably get by using the included yeast.

3. Yes, for liquid yeast there is an advantage to making a starter. Recipes vary, but the basics are water, DME, yeast energizer and nutrient. Make it 24 hours before pitching time. Dry yeast should always follow the rehydrating instructions on the packet (typically ~20 minutes in ~100F water).

4. There is a point where too much yeast can hurt, but an extra 11 g packet typically won't hurt. It could lead to a vigorous start to fementation which could create a significant amount of krausen. The krausen could overflow from your fermenter without a blowoff tube.

5. It depends how much you're talking about adding? If you're pushing over 8% ABV, I'd suggest either a yeast designed for that, or additional yeast.

6. Yes. I use yeast nutrient and energizer in every brew. Typically I add those to the starter as I usually brew with liquid yeast.

Answer 2

To expand on a few answers:

1. Yeast cells can become fatigued over time, and over generations. You don't need to worry about this as long as you're buy new yeast every time. When you start re-using yeast from a previous fermentation, you will need to worry. As for testing effectiveness - that's where making a starter (question 3) is very beneficial - since you get to see first hand how healthy the yeast look as well as starting your brew off with a nice healthy and vigorous fermentation.

4 & 5. A kit will most likely come with just enough yeast for its recipe. It's normally safe (recommended even) to pitch a lot of yeast (howtobrew.com). 100 billion yeast cells is almost the minimum for your average 6% abv brews - and 200 billion for 8% plus. Every brewer I know aiming for 7% abv or more will add yeast nutrients to ensure healthy yeast reproduction. Making a proper starter will greatly increase the cell count of your yeast, so instead of buying another yeast packet, make a starter instead.

Tto get a better technical understanding of our little friends, get the book Yeast.