question on using a yeast cake

[BrewNoob]

I have an IPA in a 6.5 gallon carboy that had an OG of 1.074. I'm planning on doing another higher gravity IPA with an estimated 1.090 OG at about the time this will be ready for secondary. Couple questions.
1) Do I need to use a clean carboy or is it okay just to siphon the new wort into the dirty carboy and shake well?
2) How long after I siphon off the first beer can I let the yeast cake sit before using if I cover the carboy and keep it in the fridge at about 66F? Or should I really add the wort the same day?

Thanx in advance.

Gerard

[Bugeater]

Before I rain on your parade, I'll answer your two questions first.

1) If you are using the yeastcake the same day, just siphon the new wort into the "dirty" carboy and let 'er rip.

2) If you are not using the yeastcake the same day, pour a quart or so into a sanitized jar with a little beer covering it and set it in the fridge. It will keep a couple weeks that way. Longer than that and you may want to use some of that to get another starter going.

Now the bad news. You are right in going from a lower gravity beer to a higher gravity beer when reusing a yeast cake. However, your original beer is a high gravity beer to start with. Your yeastcake may be quite stressed from that first fermentation. Reusing it for another even higher gravity beer will give unpredicable results. It may work just fine. On the other hand, you may be looking at mutated yeast cells that will produce off flavors or perhaps not fully attenuate. Are you sure you want to risk that after spending the extra $$ for the additional ingredients for a high gravity IPA?

I resuse yeastcakes quite often, but almost never from a beer with an OG over about 1.060. Jamil can probably give a more expert opinion here. But I would not do it myself. Just a couple weeks ago I threw out a yeastcake from a 1.075 brew instead of reusing it in a 1.085 brew even though I was using the same strain of yeast in both.

Wayne
Bugeater Brewing Company