What’s this all about? Read part 1 here.
So far the Solera has been inoculated with commercially propagated strains of yeast and bacteria and dregs from Boon Oude Gueuze. Gueuze that has been spontaneously fermented using the wild flora in the air of the Senne Valley. Having visited a number of Lambic breweries the notion of yeast wafting in from the rural idyll of meadows and woodland was quickly dispelled by walking through down town Brussels. So what does Macclesfield in the heart of the Bollin Valley have to offer? What wild yeast can I capture to give my project something unique to its locality? Time to wrangle some yeast.
Yeast wrangling, is quite simply the process of leaving wort to be inoculated by the local yeast. To do this I made a 2.5L wort using Pale DME (Dry malt extract) to an OG of 1.035, hopped 15 IBU, add a pinch of yeast nutrient and boiled for 30 minutes. This pan of wort was then covered with a fine mesh to stop insects getting into the wort and set outside over night to cool and collect yeast. This was done on a dry spring evening where the forecast temperature was to drop to 5ºC.
In the morning the wort was transferred to a 5L bottle, fitted with an airlock and moved somewhere warmer and dark to ferment.
Following the advice in the following two articles, I left this to ferment out for a number of weeks until I was sure that nothing harmful or unpleasant was present in the wort.
As can be seen in the second photo, the beer fermented out leaving a nice layer of creamy yeast at the bottom of the bottle. The wort tasted reasonably pleasant despite being a simple starter recipe, with a citrus, fruity Saison character. The only negative was a slight medicinal phenolic note on the nose, which was hopefully the result of yeast stress from having to ferment a large volume of wort from a standing start.
I have since pitched this yeast into a split batch brew, a simple APA using HBC 431 hops, with half having Mangrove Jacks M44 West Coast Ale pitched as a control. All being well the wrangled yeast will produce something nice and I can harvest the yeast cake to use in Morph Series 3.
UPDATE: The wild yeast produced a really nice, subtle, lemony saison character. With a whopping 93% attenuation.