yeast amount?

In browsing the "howtobrew" site, I've noticed that he recommends pitching two packs of yeast. I wanted to start branching out from my usual pre-packaged "kits", so just wanted to get an opinion.

Should I be pitching more than on yeast packet? I'm guessing some of it depends on the type of beer. More yeast doesnt mean a more thorough fermentation, does it? Possible to use too much? If I pitched only one packet and the yeast was fine, is there going to be a difference in fermentation it I had pitched 2 instead?

Also, I've never bothered to rehydrate. Does it make that big a difference? Is that process really only to "test" the yeast, or does it really help with the fermentation process.

Any comments/suggestions appreciated.
Thanks!
M

Depends a lot on the number of cells in the package, age of the package, and storage conditions of the package. Below 1.060 one, well stored (refridgerated) sachet is sufficient. Above 1.060SG and two should be pitched.

While not always practiced, re-hydration is ALWAYS recommended to maintain yeast health as packaged. Not re-hydrating will still result in fermentation but at teh risk of fewer viable cells, increased lag times, and potetentially increased yeast by-products and mutations. Although, the mutant cells are more of a concern if you are ranching or intend to cake pitch.

For liquid it is either make a starter or pitch 2 vials more for higher gravity beers. For dry 1 packet is good enough but 2 for high gravity beers. I dont know about lagers but generally more due to the lower temps. Also check out Mr Malty for the recommended pitching rates.

Just stumbled upon that MrMalty site.....awesome.

Thx for the info.