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New gear – stirplate

16/02/2015

stirplate

I’ve written before about my problems with liquid yeast – since I have to order from overseas the yeast has to travel in a cardboard box in wildly different temperatures. Especially in summer this can lead to poor quality and some smackpacs or vials have been useless by the time I receive them. Even when the yeast is relatively healthy it often takes a while to get a starter going (pitching without a starter is just asking for trouble as this has led to a few so-so beers with off-flavours) and I’m always a bit wary when I use liquid yeast. To get around this problem I’ve finally gotten around to getting a stirplate. It’s a simple device which has an electric motor rotating a magnet which in turn creates a field that rotates a magnetic stirbar inside the starter. The bar creates a vortex in the wort and the movement keeps the yeast in suspension. This achieves several things that helps the yeast cell count to grow beyond a simple starter. First of all the vortex created in the liquid constantly aerates the wort giving the cells oxygen. Secondly the motion knocks CO2 out of solution, which helps the yeast multiply since CO2 is an inhibitor to growth. Thirdly the motion keeps most of the yeast suspended in nutrients. All three lead to more yeast that is happier (and hopefully makes better beer).

I plan to use the striplate with an idea a picked up from the blog brulosophy – by “over growing” the starter you can gather cells for a next patch of fresh yeast before brewing a beer. This sounds simple but for some reason the thought never occurred to me… Previously I’ve tried washing some of the yeast after fermentation but it’s a lot of work and using several vessels increases the chance of contamination. By doing a larger starter and gathering a few desiliters for the next one I can both ensure that I have viable yeast for every patch and also cut down a bit on the cost.

I already tested the plate with Wyeast 1469 and the 3 or so desiliters of wort collected beforehand yielded a thick layer of fresh yeast. The rest went in to my next hoppy beer but more on that later.

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