I'd not, depending on the freshness dating on the sachet. If it's out of code, get some fresh yeast. I use S-04 or even Windsor in cider with great success.
I like to add yeast nutrients too; this helps ensure rapid fermentation. The best part is you can use your old yeast as a nutrient, because yeast are cannibalistic little buggers. Just add the old yeast to the fortifying sugar when you boil it.
well heres the deal, I bought 3 gallons of FRESH cider to ferment, and due to family issues, havn't had the time to do so... now the cider is starting to ferment in the bottles. What should I do??? is it still good to use?
should I just leave it in the basement untill this weekend (when I can purchase new yeast) or risk using the old yeast I have now?