Sowans and swats - forgotten Scottish oat ferments

Sowans (apparently pronounced 'soo-an') from the gaelic subhan or 'sughan' is a traditional Scottish oat fermentation that produces both a creamy lacto-fermented porridge (sowans), and a tangy probiotic drink (swats or strunt). The sowans can be kept either dry as a starch or in a moist form for months.

sowans in the making

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Once the oats were dried and ground, crofters and others having given the oats to the mill would get back not only the ground oats but also a bag of “sids”. These would be the oat husks (I guess we’d call this oat bran today) with little bits of the kernel still attached to them. Not wanting this to go to waste people would make Sowans out of them

Basically the process involves adding warm water to the sids and leaving them to ferment for about a week, the husks are then sieved out (and e.g. fed to chickens) and the liquid drunk fresh as a milk substitute or left to settle - a clear yellowish liquid (swats) then forms above a layer of starch (the sowans). The liquid can be poured off or drunk, and the sowans used in various ways: as a sort of porridge meal, to make a flummery type pudding, as a liquid ingredient in scones, or as a tangy oat 'milk'.

making sowans porridge

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Apparently the taste of the raw sowans is sour to a modern palate, but full of good probiotic bacteria and easier to digest nutrients. Although the pro biotic bacteria are killed if the sowans are cooked into porridge, the starch remains a good probiotic and improves absorption of minerals in the gut.

sowans pudding

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There was a similar process in Wales (and in Ireland) and a related one in Russia called kissel: which involved fermenting oats with a slice of rye bread. This was adapted by Dr Vladimir Izotov to make 'Russian Miracle Elixir' also including kefir, to treat his tick-borne encephalitis ref: https://www.beetsandbones.com/fermented-oat-kissel/

Sources / further reading:
https://cailleachs-herbarium.com/2018/03/sowens-fermented-oats-scottish-traditional-food-recipe/
https://britishfoodhistory.com/2022/10/06/to-make-sowans/
https://www.aboutorkney.com/the-wey-hid-wis/sowans/
https://rootsinfood.wordpress.com/2017/01/30/sowans-the-fermented-oat-food/comment-page-1/
Marian McNeill’s book ‘The Scots Kitchen’, a 1920s cookbook about traditional Scottish food and it’s history
https://www.uhi.ac.uk/en/research-enterprise/cultural/institute-for-northern-studies/blogs--exhibitions/mimirs-well-articles/an-experiment-with-sids-and-sooans.html
https://www.duchas.ie/en/cbes/4428244/4388005/4510317
https://tohercore.com/fermented-sourdough-oats/

I am also intrigued by sowan. I'm doing an initial experiments with what I have to hand: rolled oats, soya yoghurt & tap water.  Its probably too cold at the moment too, but let's see ..

Success! A smell like rising wheat bread dough, and a lovely tang to both sowans and swats.  

But took a full 5 days to reach that stage here in early winter even in a warm (centrally heated a couple of hours per day) room.

Here's the resulting sowans, with biofilm.

Thanks for sharing Ac - It seems that the temperature they fermented at might have been cooler, as many of the reports suggest if it is left much more than a week the result can be rather unpalatable, probably 4 -5 days is about right in a modern house. If it is too warm then undesirable moulds may also take hold, although removing the crust and discarding was an authentic action too!

I think if you are using commercial oats then adding a starter as you did is probably a wise move - once you've got it going well adding some from a previous batch is probably te easiest. Fresh 'sids' would have natural yeasts and bacteria present to get the ferment started, but milled oats are usually heat treated for improved storage life.

Did you try it as an 'oat milk' at all? How was it?

Really looking forward to trying this!  Thanks!!!

My second batch was also successful!  My house isn't cool by blackhouse standards, but probably cooler than average for today.  Again I let the ferment continue for five days.  I didn't detect any "off" odours, flavours, colours, nor textures.

The swats, or liquid, was more like rice milk to look at, but a lovely tangy, oaty flavour.

I had the sowan raw with a heaped teaspoon of cooked Japanese quince puree which enhanced the tanginess and was very tasty.

I now feel confident at trying a batch with the ferment from my own sowan with live soya yogurt starter, to see if that works.

now I want to try🙃

Is there a simple ratio of oats to water?
We always have rolled oats on hand and I can run them through the grinder.
I have my homemade yogurt but is it necessary? I just reread and see where it would be helpful as even though my rolled oats are organic they might have been heat treated along the way?

and our kitchen is really quite cool.....

If anyone interested in this subject has Sandor Katz's Fermentation Journeys (or gets it from the library), check out page 100 for Kisiel.

I use rolled oats, no further processing, roughly double the volume of tap water to float them, a small spoon of live yoghurt stirred in, and cover with a cloth for about five days.

Not very precise at all!

I like this ferment too, I use a gallon jar half filled with  oat flakes and /or wheat flakes, or other cereal , then fill with water leaving headspace, cover with a plate or a cap not tighten, stir daily as some float

whole rolled oats, ex:
https://ro.iherb.com/pr/now-foods-organic-rolled-oats-24-oz-680-g/14006?gad_campaignid=23087017151&gad_source=1&gclid=Cj0KCQiArt_JBhCTARIsADQZaykg1I_disgqVCsKF5m_M6z4dn4F1HimdrYNjMB0z8I61YXLh0U0YN4aAv-VEALw_wcB&gclsrc=aw.ds
are my preference, in about 4 days I start using the mash in smoothies or in cooked porridge, there is nothing inedible inside , no need to sieve , filter nor decant. Also I use no starter , it sours just fine (will water , leave tap water overnight)

Thank you for all the links!  
Will make this, it looks fascinating and delightful

I’ve been getting into sowans lately. I’m thinking since my source is not sids but rolled oats, maybe I can use the rest for oat cakes. I’ve been making fermented oats for the first time after over a year of avoiding grains and they haven’t had any negative effects so far. I have a feeling that fermentation (and spouting?) may be essential for my ability to eat them without issues.

More on a similar Russian fermented porridge, kissel:

https://www.beetsandbones.com/russian-fermented-kissel-porridge/

M Ljin wrote:I have a feeling that fermentation (and spouting?) may be essential for my ability to eat them without issues.

If you're sensitive to fructans these are digested as part of the fermentation process. Oats are moderate in fructans - not as bad as wheat products, but still significant amounts.

I don’t think that is the issue as it is only grains.