Hefeweizen smell/ taste from S-189 Starter

[Red Baron]

I have a question I'd like some feedback or answers on from the great brains trust that is AHB.

Currently I'm culturing up a starter of S-189 from the dregs of one of my bottles. I don't have a stir plate, so have been doing it in a juice bottle and shaking it every time I walk by. Starter wort is made from 10% weight LDME and boiled water, allowed to cool in the fridge in a sterilised container.

Steps so far are: 1. dregs to 10ml in tallie
2. added 45ml still in tallie
3. added 200ml and transferred to sterilised juice bottle
4. added 1L

The yeast is kicking along nicely, and I have it fermenting at ambient (currently 30/32deg during the day in CQ).
Today when I opened the lid to allow some oxygen in, I noticed it smelled very much of a warm Hefeweizen (big banana, slight clove). Curious, I tasted it. It tastes fruity, with a small clove linger at the end. Apart from that it finishes quite well- no other off flavours discernible.

I know clove can be a phenolic indicator and point towards infection, but my question is this:
Can the banana and clove flavours be purely from fermenting this lager yeast 20deg above it's normal range, meaning the starter will be good when the beer is decanted and yeast pitched at an appropriate temp, or is it likely infected and chuck it?

Thanks for your help,
RB

 

[Red Baron]

Bump- anyone????
I've got it cold crashing at the moment, and am going to pitch the next step up onto only the yeast and let it run at cooler temps to see if the hefeweizen returns.

Cheers,
RB

 

[technobabble66]

Hey RB,
Not sure if i can help you much, as i've only used S-189 twice.
FWIW, i don't recall getting anything like what you're talking about in terms of aroma from the 2 batches i did (didn't do starters tho).

However, you seem to be on the right track. I'd guess the smells from the first starter might just be from stressed yeast that's been recovered from a stubby and grown at 30+°C. I know the 30-35°C range is ideal for growing the stuff, however it's obviously not ideal for beer, and that might explain the odd aromas.
I'd do as you mention in your second post: try a second starter and see how it goes. This generation should be much less stressed and is also at a temp that we're more familiar with. If it seems good then go with it. If in doubt, toss. (NB: it'll maybe throw out some sulfur odours, so keep that in mind when sniffing).

Also fwiw, did you add boiled water to LDME; or add LDME to water, then boil it?
I ask because it's fairly important to boil the starter wort to sterilise it.
The basic theory is that you need to be extra careful with starters as any mistakes (i.e.: minuscule infections) will multiply dramatically, whereas you can generally get away with slightly less draconian sanitation methods in a regular batch. I think the belief is that the quantity of yeast in a batch is generally so high that they'll overwhelm most/some bugs that may be present if in tiny amounts. The nature of a starter is such that even tiny amounts of bugs will be proportionally much more significant, and so starters are more prone to developing infections. (OTOH, starters are good for revealing if your batch of yeast does have any bugs lurking within).

Best of luck with it. I was v happy with my results off S-189 (done at 16°C & 18°C!)

 

[Red Baron]

Thanks for reminding me about the need to boil the wort after I add the DME- I just added boiling water to it this time. Tomorrows step-up will be boiled then cooled. It will be interesting to see how this one turns out anyway.

Cheers,
RB