WLP001 Sour Starter - Final Word?

[Never a dull moment.]

What's the final, if any, determination on WLP001 and sour smelling and/or tasting starters? There are posting all over the web, but there doesn't seem to be a consensus of any kind. Understanding that sometimes it *will* be an infected starter, it seems some degree of sourness happens often, if not usually, when there is nothing wrong.

I just did a starter with this yeast. 1k ml in a 2k ml flask, DME (6 Tbs, 2 tsps), 1/4 tsp yeast nutrient, boiled for 15 minutes. The flask was washed well, but not sanitized as I figured the heat from the boiling would do it for me. As I've seen has happened to others, the vial foamed up after I shook it and some of the yeast was spilled (White Labs says the foaming is normal and one should wait a few minutes before opening the vial after shaking it). The exterior of the vial wasn't sanitized.

The starter went on a stir plate for 48 hours in a temp-controlled chest freezer at 72-73F. After I turned off the stir plate, the starter remained in the chest freezer at 63F for another 12 hours, in part to let the yeast settle. Then I pitched after pouring out about half the liquid.

The starter had a faint, but noticeable sour smell. I'm still working on my palate and nose, so it's entirely possible I had it wrong. However, the smell would bring immediate images of Belgian sours.

As I said, I pitched it anyway, figuring something in the process caused the generation of these compounds and I'm relatively confident of my sanitation procedures.

The recently published book "Yeast", which I think is excellent, provides some good info on the yeast life cycle, including the fact that they do generate a variety of organic acids, including acetic and lactic.

So, what is the consensus on this?

I never smell or taste my starters. So....if your confident in your procedure and the fermentation is going as it should. What's the concern? I've never (knock on wood) had a bad/infected starter.

I reuse yeast because doing so gets me (1) better yeast in later generations and (2) it saves me some money. Because those are my goals, I only reuse yeast that came from a really great ferment, and that I am confident will produce great beer the second time around. If my starter doesn't seem likely to yield good results, then I'd just be wasting the cost of grains and hops by pitching it.

If you were trying to make a starter for a platinum strain that's only available during certain month, or even for one of the pricey Belgian strains, I might suggest deviating from this general rule. (Roseleaire is a hard strain to find sometimes, so repitching a stepped-up starter from a jar you've had in the fridge for six months is sometimes your only option!) But WLP001 is the same thing as US-05 dry yeast. If you're even SLIGHTLY uncomfortable with the look/smell/taste of your starter - like you, I'm someone who smells and tastes - then it's better to break out an emergency dry yeast packet than to take the risk of brewing with contaminated yeast.

So, in short, my theory is. . . I don't know if your yeast is contaminated, but you claim that it might be. If that's true, then, given how cheap and easy the alternative is, I see no reason not to use new yeast.

Hammy71 said:

I never smell or taste my starters. So....if your confident in your procedure and the fermentation is going as it should. What's the concern? I've never (knock on wood) had a bad/infected starter.

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I was disconcerted by the unexpected sour smell. Normally, I would associate that with something having gone wrong (except where expected). But upon researching, it turned out that many, many other people are reporting the same thing all over the web, but most of the posts leave one wondering what the final determination was/is.

pericles said:

So, in short, my theory is. . . I don't know if your yeast is contaminated, but you claim that it might be. If that's true, then, given how cheap and easy the alternative is, I see no reason not to use new yeast.

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Fair enough. And I made the conscious decision to pitch it.

The question is: given the testimonials out there that a very specific yeast, WLP001, is demonstrating this behavior, I'm only trying to learn if this is something normal that one can expect.

Funny you mention this I had a similar experience and was searching through google for answers. In my case I was using a very old vial of wlp001, about 3 years old. I was ready to pitch dry yeast if I had to but mostly wanted to see if I could revive this tube. I made a 500ml starter at 1.020 gravity and after a week I noticed I had some yeast forming and the starter was fermented out. I then stepped up to a 2 liter starter on a stir plate and after a day or two it was done. I went to take a gravity reading just to be sure the starter was done and immediately noticed a kind of rank sourish odor with a strong whiff of clove. I immediately thought damn this thing might not be good. However I know CO2 can smelly pretty rank and I usually let my starters go on the stir plate for around a week so, in that time the CO2 probably dissipates for the most part. I crash cooled the starter and while decanting tried some of the beer. It tasted yeasty but for the most part very clean and a little malty. So going off of flavor I ended up pitching the starter. I will report back here how the batch is hopefully did not ruin a batch of beer.

ASantiago said:

Fair enough. And I made the conscious decision to pitch it.

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You pitched it in the wort or you pitched it down the drain?

The question is: given the testimonials out there that a very specific yeast, WLP001, is demonstrating this behavior, I'm only trying to learn if this is something normal that one can expect.

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From my experience, it's normal. I just pitched 001 on saturday and it had this slight sour smell, just like the ones before it. All have turned out fine.

bja said:

You pitched it in the wort or you pitched it down the drain?

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I pitched it into the wort.

jtejedor said:

Funny you mention this I had a similar experience and was searching through google for answers.

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It was because of my inconclusive searches through Google that I decided to start this thread, making sure the keywords "WLP001", "sour", and "starter" are part of the title and text so (hopefully) this thread will shed a little better light on the issue (if any).

Like you, I will be reporting on the results of my having used the yeast anyway. As I write this, the fermentation is going strong and I estimate it will be done by the weekend. At some point in time right after that I will give it a good whiff and taste, although I may let the fermentation complete through the clean up stage.

i made a starter from rinsed WLP001 yeast about 4 weeks ago and experienced the sour/odd smell. I got about 4 mason jars when i rinsed and that jar was the only one that produced that sort of smell with the starter.

Anyways, i decided to use it and 4 weeks later, no off taste from the racked beer nor were there any visible signs of infection. so i hope that makes you feel a bit better.

I just didn't feel that with that short of a time frame, any real souring infection would be noticeable. Sign of less than optimal yeast health from the start? Maybe, but it was all i had to pitch. The wort reached the expected final gravity and a controlled fermentation yielded no outrageous off flavors yet, so so far so good.

Jwood -

That's the thing. It was "pitching time" and I had nothing else to pitch. So I went for it.

Reading the yeast book, I'm getting that it is entirely possible that this yeast just behaves like this, although I find no conclusive evidence. It's possible that 48 hours of aeration at a relatively warm temp (72-73), plus another 12 hours of settling time may cause this. Everything else I did and the materials I used are pretty much the same as for previous starters. The yeast is the only change.

Yeah I sniffed the fermenter and so far it does not have that rank smell the starter did. Smells like a normal fermentation with a bit of that CO2 sting. It is a really hoppy beer though.

UPDATE:

Last night I racked the beer to a keg for cold conditioning. There was no sour smell and the beer tasted great. As far as I could tell, the fermentation went well and the yeast I pitched was healthy.

To set the context: I pitched the yeast at 63F into wort also at 63F. I had both sitting in the temp-controlled freezer. At the time, the yeast had the sour smell I reported. Fermentation took place between 65F and 68F (fluctuations due to temp diff between beer and air temp). After 6 days, gradually increased the temp to 72F for four days for final fermentation and clean up.

Considering all the reports I found, the sour smell (I didn't taste it) this yeast displays seems "normal" in the sense that, outside an obvious infection, it may produce those aromas.

What I suspect happened was I stopped the stir plate, and hence the constant aeration, two days before I pitched, but kept it at the same temp, 72F. The lack of aeration may have caused the yeast to kick into fermentation mode, rather than reproduction mode. As part of this, it produced the sour smell. But this is all conjecture on my part.

The bottom line is that, not only am I happy with how the beer turned out, but I'm harvesting the yeast to use with my next batch.

Yeah mine stalled out but I think it may have been age and maybe not stepping up or letting the starter grow enough. It actually threw some very belgian like esters. Very strange for wlp001.

jtejedor said:

Yeah mine stalled out but I think it may have been age and maybe not stepping up or letting the starter grow enough.

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Do you use a stir plate?

Yeah I do. Thinking back the vial might have been 4+ years old. I started with a half strength half liter starter and stepped that up to a 2 liter starter on the stir plate for a few days. The starter seemed fermented out and the yeast was rocking away on the wort at first. Had crazy blowoff. But after a couple of days the krausen dropped and the beer seemed stalled at 1.044 (started at 1.076). The recipe was a highly fermentable ipa, mashed at 151 with a half pound of corn sugar. I pitched 3 packs of Cooper's yeast I had laying around and it took a few days but that kicked off and got the beer down to 1.012. The stressed yeast must have thrown esters and phenols because this American iipa tastes pretty Belgian. Its actually not unpleasant at all,l tasting a sample today it reminded me a lot of urthel hoppit or houblon achouffe.

FINAL UPDATE:

Just a quick note to close out the original thread and the concerns I posted about. From the same yeast that I thought was bad, I got a very clean, tasty AIPA which I'm now enjoying. I also harvested the yeast from that and used it for a Robust Porter that I just began drinking this past weekend and it, too, turned out very nice.

I now believe the original sour smell may have been due to the higher temp at which I kept the yeast after I got it off the stir plate and while it was waiting to be pitched. If you experience similar conditions, it may be just fine to use it.

Your mileage may vary.