A minor tragedy

The kolsch I recently brewed (see here), has been cold conditioning for a week, though I should really have just thrown it down the drain.

I have made this before, and I used White Labs WLP029 yeast which gave me a beautiful delicate kolsch. Unfortunately White Labs yeast is not available in Melbourne and so I had to order it from a New South Wales home brew shop. This had put me off brewing the kolsch again, but I recently found six bottles of last years version hidden away in my house. I decided to culture up the dregs from these bottles, and did so without undue difficulty. The first 200ml starter seemed to behave normally, as did the 500ml and 2L starters I then pitched to. The fun stopped when the main batch was innoculated. A very long lag time and a very slow fermentation got me worried. From my notes I could see that the fermentation was way behind schedule after a week, and so I took the dramatic step of making another starter and re-pitching to the main batch.

This helped things along a lot, but I think it may have been too little too late. From the first hydrometer samples I could detect phenolics, clove especially. This should always set alarm bells ringing, and it did, but I was hopeful that these volatiles might dissipate with time. When it came time to cold condition I could still taste and smell the phenolics, and a week in it's as bad as ever.

We know that some yeasts produce these compounds in a normal fermentation, particularly wheat beer yeasts, and wild yeast. I hadn't thought that WLP029 would produce them, and had put this problem down to a wild yeast infection. Now I'm not so sure. Firstly, the beer is completely clear, its appearance is actually picture perfect, exactly what I expected. Secondly it finished at exactly the same gravity as my first batch. Thirdly, there are several reports from home brew forums of this problem with this yeast. See here and here

Here's my theory:

The yeast I procured from the old bottles had very low viability. I tried to culture this up in a 200ml starter, and it did fire up, but it's possible that having started with such a small amount even a doubling of the cell count resulted in very little yeast. This problem then followed me through the other two starters, and I ended up underpitching this batch quite severely, a low fermentation temperature exacerbating the problem. The yeast, susceptible to these issues, in far from optimal conditions, was extremely stressed and secreted these unpleasant phenolics during replication/fermentation in the initial stages. After a sluggish start I pitched another starter and got things moving a bit, but the damage had been done.

The lesson:

Watch your pitching amounts, especially where you are using old yeast in cool conditions.

The plan:

I'll rebrew as soon as possible. I've already ordered a vial of WLP029 from another NSW homebrew shop, along with a vial of WLP006 Bedford Ale which constantly gets great reviews over at perfectpint.blogspot.com. I'll be making a big stirred starter and looking for a quick clean ferment.

The result:

About $18 of ingredients and 3-4 hours of my brewing time, plus minutes here and there to look after it, have been lost. I say lost and not wasted because once again I've learned more from this bad brew than I would from ten good ones. As long as I can explain problems I'm not overly worried about them.

Next Step:

A rebrew, I will have my Kolsch come hell or high water!