Tuesday, 4 July 2017

Brewing Kvass

Kvass is an ancient folk beer from Eastern European and Russian parts. It's what used to be called a 'small beer' - very low in alcohol (in the region of 0.5 to 2% abv) and generally consumed young and fresh.

There are several characteristics that distinguish kvass from current mainstream beers:

  • The fermenting organisms. Like sourdough and kimchi, kvass is based on lactofermentation, with a mix of lactobacilli and wild yeasts doing the business, in contrast to the pure brewer's yeast strains typically used in beer brewing.
  • The ingredients. Kvass is made from sourdough rye bread, a sugar source, and water.
  • The time it takes to make it. Kvass goes from combining ingredients to drinking in about 4 days.
  • How easy it is to make. Even if you have no homebrewing experience or special equipment, kvass can be made using gear that most everyone has in their kitchen already.

The drink itself is a refreshing and nutritious brew, packed with vitamins, probiotics and gut-friendly lactobacilli. It has a pleasant 'tang', due to the lactic acid content, just verging on sourness. Those are its general properties. The specifics are highly variable and offer a rich field for experimentation.

  • The sugar source can be anything from treacle/molasses, through malt extract or honey, to brown or even ordinary table sugar. The resulting brew flavour is quite different in each case.
  • Then there's a whole universe of possible additives, just for the flavour. Fruit, berries, herbs - apparently one's imagination is the only limitation.

If you bake with sourdough, then you've already got everything you need to brew kvass. Even if you haven't got a sourdough starter in the house (and seriously, you need to remedy this as soon as possible), you can make do with using bakers yeast, since it is generally contaminated with lactobacilli which, in this case, is a good thing.

Now, on to the basic method:
Rye cubed.
  • Take 450g (1lb) of rye bread (ideally homemade sourdough). If it's stale, so much the better! Cut it into sugar cube-sized pieces, spread them out on a baking sheet and pop them in a warm oven (not hot enough to bake bread) until they're completely dried out, but not so long that they burn.
  • Next, place the dried bread cubes into either a large pot, or food-grade plastic bucket, and pour 5 litres (just over a gallon) of boiling water over them. Any fruit or herbs that you wish to add can be popped in at this point. Cover and leave to soak for as long as it takes to drop to around 30°C (86°F).
  • From this point on, use good sanitary technique - make sure that all equipment is well cleaned.
  • Strain the liquid out, through a muslin cloth or a fine sieve, and into your brew pot, bucket or demijohn - whatever you want to do the fermentation in.
  • Add 300g (about 1.5 cups) of your chosen sugar source.
  • Add 100g of reasonably fresh sourdough starter culture.
  • Give it all a good mix together and leave, covered with a towel or under a fermentation lock - depending on what equipment you have available - for a day. After this time you should see a foamy surface layer, indicating that you have a lively fermentation going on.
  • Now bottle it - siphon or pour through a funnel, leaving the sediment behind, keeping a decent air space at the top of the bottle. Tightly cap the bottles, and leave them somewhere cool for a day to finish fermenting. Plastic bottles (recycled fizzy water or other soft drink bottles) are a good choice, since you can easily tell if they're becoming overly pressurised. This is 'bottle conditioning': the fermentation continues inside the sealed bottle and builds up pressure, naturally carbonating your beverage, giving it a wee bit of fizz. If the bottles start to balloon out, just loosen the cap slightly to depressurise.
  • Now refrigerate, leave for a further day or two, and then pour and enjoy!
Apparently, kvass will keep for at least a month in the fridge, but good luck resisting the temptation to polish it off long before then!

A healthy and vigorous fermentation.
This is a cloudy brew, full of goodness. You'll find some sediment at the bottom of your bottles - don't try to avoid it, it's just a collection of beneficial microorganisms that your gut will love.

In our first kvass brew, we used a mix of treacle (molasses) and malt extract syrup as the sugar source, and no other flavourings. The treacle imparted a distinct licorice flavour to the brew, which I liked, but which didn't appeal to the missus. No more treacle! But still, it was good enough to convince us that kvass brewing was an avenue worth pursuing further.

Ideal for refuelling after hard labour in the garden.
Second time around, we used a mixture of malt extract syrup and honey, and added some sprigs of lemon verbena, fresh from the garden, to the soaking bread. This turned out an altogether much classier brew, with subtle notes of honey and a beautiful lemony zing.

Kvass is an amazing discovery for us. A lightly fizzy beverage, without loads of sugar or other rubbish ingredients, and with high nutritional value and gut-friendly microorganisms. We're definitely looking forward to many more experimental iterations and exploring where kvass will take us.


  1. I believe I had the honey/malt extract with lemon verbena version? It was perfect, especially after a few hours in the punishing Scottish summer :)

    I'm going to give it a go this week, once I round up my equipment.

    1. It was honey/golden syrup, with lemon verbena and hops. Now we're onto Demerara sugar with lemon verbena - recommended!

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