If I am making a yeast starter with wyeast, is there ANY reason (besides checking viability of old yeast) to smack the pack and wait for it to expand? Or, should I just sanitize, cut it open and put it in my starter wort?
I wouldn’t worry about it - theoretically if you don’t have time to make a starter today but want to get the starter ready in 2-3 days, then I guess smacking it would wake up the yeast and save some time. But if you have time to do it anyway - there’s no point waiting for it.
Smack it and pour it all in. The little pouch is extra food for the yeast. No need for the pack to swell before pitching.
I smack it as soon as i leave the store, that way the yeast is awake and partying by the time it hits the starter wort. If you are already ready to go still smack it before you pour it in.