I've got a "house" strain that started life as a Wyeast West Yorkshire smack pack about ~2-3 years ago and has been up to now a very reliable yeast.
However I have noticed in my last two brews a change in behaviour once bottled.
Normally this yeast drops out of suspension like a cut lift, and stays in the bottom of the bottle. It is still dropping out, and the first ~100ml is "pub clear." The yeast however then immediately jumps back into suspesnsion during the pouir and it becomes cloudy (it has never done this before). On the more heavily carbonated bottles it jumps straight back in as soon as the cap is popped (and unusually I've had the odd "gusher" recently).
I understand that yeast will mutate and deviate from the original strain over time (I remember reading something about only reusing yeast ~5x before dumping, but I'm way past that number with no issues until now...). Is there anything I can do to "re-train" it into sticking to the bottom of the bottle like it used to?
I'd quite like to keep this strain going rather than dump and re-buy, what would you suggest?
I should probably specify what kit I have access to:
- DIY stir-plate & 2L Erlenmeyer [sp?] flask
- 5l demijohns
- malt extraxt for making starters
- yeast nutrient
- No microscope
- No slants, etc.
[EDIT: Just seen the price of a new smack pack, **** me those have shot up! ~£14-16.00 posted depending on where you buy it from! Definitely want to salvage this strain if I can...]