Yeast character shift

can/does yeast character shift? I have a sample of White Labs WLP 300 hefeweizen yeast I have been ranching for several years. I didn't do a hefe last year ( didn't get to it) so the sample may well have lain undisturbed for 24 months. Did a starter and it finished off the starter wort quietly. Pitched it and it fermented the batch out to the desired FG. However, the resultant beer has no hefe esters. I want my banana!!! Is it possible for the yeast to have shifted? I hadn't thought of this until drinking 2 kegs of beer that tastes like BMC. Not bad, just not what I was brewing for.

How many generations (batches) from the original sample?

william_shakes_beer said:

can/does yeast character shift? I have a sample of White Labs WLP 300 hefeweizen yeast I have been ranching for several years.

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Yes. Actually, hefe yeast is pretty notorious for this. Depending on your storage method, mutation is very likely after a period of time (unless you're deep freezing your bank). In recent years there has even been noticeable variation from a major yeast supplier despite their QC efforts and tech.

If I was storing a slant in the fridge, I would only trust it for 3-6 months.

ok, guess I'll discard this sample and purchase fresh hefe yeast in the future.