Fermentis Safkvas C-73 Experience

[Protos]

Continued from another thread.

I got me some Fermentis Safkvas C-73.

I tasted homemade Kwass many times in Latvia (my home country, where Dzersis is another name for the beverage, although Kvass is used more often) and in Poland. I'm familiar with three versions of Kwass: the common standard farmhouse bright yellow version made of stale Rye Bread, which I never liked neither aesthetically (the soaked-bread mud sunk on the bottom looked just yucky) nor tastewise as it's pretty sour. Each country also has its additional unique variety: in Poland it's a Kwass made of Red Beetroot (which to my liking tasted even worse than the stale bread version), and in Latvia, I tasted a much better Kwass made of fermented Birchtree Sap. My grandparents used to brew it. Sadly, I have no idea on how it's made.

The best ever Kwass that I really liked and want to emulate now I tasted in Ukraine. It was an industrially-produced beverage, much darker and sweeter than the homebrewed versions I drank in Latvia and Poland. There were several brands available, I remember by name the only one: Jarylo (which has nothing to do with the American hop, as Jarylo is the name of an ancient Slavic deity of fertility and it's here where the names both for the hop and for the Kwass brand come).

For my first own Kwass recipe, I decided to discard the sloppy traditional practice of open wild fermentation of stale bread. I made my small batch of Kwass all-grain, boiled and fermented under the hydrolock, to see what the C-73 yeast alone can achieve. Then I will adjust the recipe to replicate the Ukrainian dark sweet Kwasses. Grain to glass in 3 to 5 days, it's an ideal style for experimenting.

As I understand, Kwass differs from the rest of the small farmhouse ales in that it's double fermented: first by Lactobacillus, and then by Cerevisiae or wild strains. Fermentis state their Kwass yeast provides enough acidity, so that no additional Lacto fermentation is needed. Which means, I don't have to perform any open wild fermentation to get the necessary tartness.

Well, here's the recipe I came up with:

RUDZU DZERSIS
(Rye Kwass in Latvian)

OG 1.024
FG 1.012
ABV 1.6%
Attenuation 50%

Pale Rye Malt from Weyermann - 1/3 of the grist
Red Fermented Rye Malt from Lithuania (aka Kaljamallas in Finnish Sahti recipes) - 1/3
Rye Flour from Finland (didn't want to use adjuncts, but Rye Flour is present in each and every traditional Kwass recipe, so included it too) - 1/3

Mash 30' @48°C / 118°F (flour made the mash awfully gummy, so a beta-glucan rest was necessary)

Mash 120' @70°C / 158°F (with so little diastatic Pale malt in the grist, I wanted to give enzymes some extra time to convert all starch - which actually resulted in a 100% extraction efficiency. No beta-amylase rest, as I didn't need much alcohol in this brew).

Boil 15' (just to clarify somewhat the turbid cloudy floury wort)

Safkvas C-73 - 0.2 g per each 1L
(fermenting under hydrolock, to exclude wild yeast and Lactos impact to better assess what C-73 is capable of)

 

[Protos]

I planned to ferment my wort for 2 days at 28°C and then cold crash to stop fermentation to not get too much of Alcohol, but then I had to leave my home for 10 days, leaving the wort in the primary all that time. I was expecting I would have gotten a standard-strength 4% or 5% ABV beer, but no, C-73 fermented the wort down to only 50% apparent attenuation. It turned out, it was even better I left it for longer, as the floury haze partly settled down (though not completely).
I liked the flavours imparted by the yeast very much. C-73 is a single-strain Cerevisiae, no Lactobacillus blended in it, and even so it created a very pleasant and delicate, not excessive Lacto-like tanginess. The ester profile is pretty peculiar, it's hard to point my finger on it but it's exactly the flavour I remember from the dark sweet Ukrainian Kwass. I bottle-primed my Rudzu Dzersis in plastic bottles (as Kwass requires a very high carbonation about 4v) and very soon it was ready.
I got a very good drink, definitely better and nobler than the homebrewed versions I've tasted before. Because of a clean yeast culture, no rustic wild notes are present, and because of the lack of Lactos, no excessive acidity. A perfect refreshing drink for the current heatwave. It tastes like a pretty close substitute for a beer (actually, it IS a beer, just a small one) which I can drink however much I please without thinking of the drawbacks of excessive alcohol intake in the heat (which drawbacks, to be honest, are felt on the health more and more prominently each year as I age).

For the next recipe, I'll change a couple of things:
- NO RYE FLOUR ANYMORE, NEVER EVER. Maybe Rye Flour is OK for a traditional sloppy non-sparged non-filtered non-boiled technique, but with a standard beer setup 33.3% Rye Flour in the grist proved to be disastrous. Previously I successfully brewed a couple or two of 100% all-Rye-malt Roggenbiers and managed to sparge them, albeit slowly, but with Rye Flour I got stuck sparge even with a BIAB. So, Rye Flakes for the next time, and the rest of the Rye Flour I bought specifically for my Kwass experiments all goes for baking Polish Perniki Żytnie, to complement my Kwass with some fitting sweet pastry.
- next time I'll add some Black Rye Malt for colour. Kaljamallas is pretty dark but not dark enough to render the Kwass Schwarzbier-black, as it should be.
- will have to backsweeten my Kwass and then pasteurise it. Although the attenuation with C-73 goes pretty low, the all-Rye wort wasn't particularly sweet even when fresh, to start with. So the resulting Kwass has a nice tanginess but needs more sweetnes to counterbalance it in a nice way.
- will probably split my next batch in two, to see how it takes a bit of Blackstrap Treacle. I think there was a hint of it in that Ukrainian Jarylo Kwass, which I liked a lot.

Will report the further proceedings of my quest for a perfect Dark Sweet Kwass here.

 

[dmtaylor]

Pictures or it didn't happen.

 

[Protos]

Visually, there's little yet to be proud of, to tell you the truth.
Floury haze. Murky. Not dark enough. That's why I drink it from an opaque ceramic Stein.
For the moment, the report is rather about my first impressions on the yeast, than about the product itself.

I hope, later I'll have better batches to not be shy to publish photos of them in all their Kwassy splendour