I found some jars of sour cherries in Lidl & had to have them to make a beer with. While it will have some resemblance to a Belgian Kriek, it is not soured with wild yeasts or bacteria. The sourness will come from acid malt predominantly.
Mash: 1 hour 10 mins starting at 70°C & falling to 57°C at the end.
2 Kg pale malt
250g acid malt
150g crystal malt
Boil: 1 hour
10g Archer hops (5.0% alpha acid) added 30 mins before end of boil
700g of sour cherries that had been through a food blender added at flame out
The wort was chilled to 18°C. The 660g of bright red syrup from the jars of cherries was poured straight into the fermenter along with Mangrove Jack's M44 yeast recovered from a previous brew & kept in the fridge for a few weeks. The chilled wort was splashed through a colander & into the fermenter to aerate it.
The OG of the cooled wort was suprisingly 1.050, but I guess I underestimated how much sugar was in the syrup. The gravity at bottling was 1.018 - higher than I was expecting. This should give a beer of around 4.2% alcohol & around 4.3% once the priming sugar has carbonated it up. The mash could have been better temperature controlled, but there must also be plenty of unfermentable sugars from the cherries too. With the length & temperature of the fermentation this will be as low as it'll go.
Bottled after 8 days fermenting mostly at 20°C, but rising to 22°C for the last 3 days with the summer temperatures reaching 28°C outside.
Verdict at bottling - disappointing. The beer was still very turbid & not sour at all. I really expected the acid malt to give it a sour bite, but it's just not there. The cherry flavour is modest & I cannot detect any hop bitterness at this point.
Hopefully when the beer has dried up a little more, cleared a little better, carbonated up & served chilled it will be very different.