Brew Notes: Pepo - Watermelon Gosé

Gose is one of my favorite beer styles. Tart, briny, effervescent and refreshing - you get the idea. In this little tweak, I wanted to up the refreshment factor by adding the unique notes of fresh watermelon. It didn’t come easy though, and took a few tries to get right. Watermelon is finicky to work with, and the pulp is a nightmare to get out of the beer. 

I’m not a fan of kettle sours (quick souring using Lactobacillus alone) as I find that the end product lacks complexity. However for this recipe I went with kettle souring, as I didn’t have an extra dedicated wild keg on hand. 

A respectable amount of acid malt was added to inhibit proteolysis of foam-forming proteins by the lactic acid bacteria (LAB). Mashing was done as usual, and L.plantarum and L.gasseri was added. The top of the Grainfather was covered in foil, and allowed to ferment at 36C controlled by the heating element. The lactic acid fermentation was stopped when pH dropped to 3.2, with a short 20-minute boil to preserve a light golden colour. 

The yeast strain I used was Voss kveik, originally from The Yeast Bay. I needed to ferment at ambient temperature without control, and I felt that the unique orange-like eaters from Voss will complement the overall character of this Gose. I was not disappointed! At the end of primary fermentation, the frozen and partially-thawed juice of 2 watermelons was added. This was allowed to ferment again to terminal gravity, before being filtered through a nominal 10 micron beer filter and carbonated to 2.5 volumes CO2. 

Batch size 23L

Boil time 20mins 

OG 1.043

FG 1.009

Bitterness 0 IBU (yes I know ...) 

Alcohol 4.6% ABV

Grain Bill:

44% Pilsner Malt 

44% Wheat Malt 

11% Acid Malt 

Hops:

None! 

Additions:

14g sea salt @ flameout 

28g coriander @ flameout 

Yeast & Fermentation:

Lactobacillus plantarum 

Kveik (Voss) 

Secondary:

Juice of 2 watermelons 

[Before filtering - look at those bits of watermelon floating!]

Tasting notes:
I was expecting some orange notes from the Voss kveik yeast, but that didn't really come through strongly or individually, which is good! Aroma is distinctively of watermelon and in particular, watermelon rind - that refreshing, watery aroma (does that make sense?) that is very much reminiscent of cucumber. Pretty fair head retention which I attribute to pre-acidification, but slightly under-carbonated for style I feel. A good tart acidic note comes through in the aroma, which has some lemon-like qualities. For some reason, the beer dropped sparkling bright - not exactly to style (it ought to be cloudy), but I feel this makes for pleasant visuals in this beer.

Mouthfeel is light, with upfront lactic sourness that is clean and short-lasting on the palate. Once again the taste of watermelon rind is subtle, with not much presence of the watermelon fruit character this time. A slight grainy sweetness is apparent from the Pils malt. Salt presence is barely perceptible and only as a sense of freshness, not unlike that of an electrolyte drink!

In all, I love this beer (and so does my wife). It takes quite a bit of effort to brew however, and in future batches I will experiment with a slightly increased watermelon presence.