I’ve been reading an amazing book called The Art of Fermentation by Sandor Ellix Katz recently. It’s full of ferments (not just beer) from around the world, some with exotic and hard-to-come-by ingredients, but one sentence stuck with me. Katz wrote that, apart from its health benefits, fermentation has always been used to preserve surpluses from the local area, especially in the days before fridges. I sympathise with the idea – I’ve been putting together ingredients for an alcoholic root beer, and whilst they smell amazing, some of them are shipped from thousands of miles away. So I decided to do a beer which is as cheap as possible, and with the smallest possible carbon footprint. Hence turning to the only surplus from our garden last year: the box of mouldering jerusalem artichokes in the garage that nobody fancied eating.
Jerusalem Artichokes are not true artichokes. They are related to sunflowers (girasole in Italian), and their name is an anglicisation of girasole artichoke. The root tastes good and is sold for a high price in Waitrose, but contains a high proportion of inulin, a carbohydrate which is sweet in taste but impossible to digest. The bacteria that live inside us love it though, and produce various gases whilst they metabolise it.. not pleasant.
Inulin can be reduced by some methods of cooking, but can also be metabolised by a species of yeast present in the symbiotic microbial community called Kefir: Kluyveromyces marxianus, which produces the enzyme inulinase. Kefir is sour tasting because of the lactic acid bacteria it contains, and I’d prefer to brew a normal ale rather than a lambic style, but maybe I’ll try pitching a small quantity of kefir with the Trappist ale yeast I bought. Just let the microorganisms fight it out.. kefir is said to be highly adaptable, and potentially, if it’s introduced to a solution with a large amount of inulin, the inulin – digesting yeast might out-compete the lactic acid bacteria. Maybe.
Jerusalem Artichokes store most of their energy as starch, similarly to potatoes. That means I’ll have to perform a mash a bit like the first stage of vodka production, in order to break down the starch into sugars using the amylase from the malt. I found a vodka recipe which calls for only 1kg of barley to 25kg of potatoes, so if I use 2kg of barley to a few kg of artichokes I should be fine. I’m new to mashing, so I’m going to make things easy on myself. In case this paragraph is ambiguous, I’m not going to distill this into vodka – this is going to remain a beer, for good or ill.
I wouldn’t be surprised if the beer gets cloudy, so I’ll add a fair amount of Irish Moss during the last 15 mins of the boil.
I’ll post a full list of ingredients, and the method I used, once I know if this experiment is worth repeating.