Unlike many sour beers on the market today, Ltd #20 is not a kettle sour (where the wort is pre-soured with lactobacillus in the kettle, before boiling).
Instead we used a yeast that is commonly used in the wine industry, but whose use is only starting to be explored by the brewing industry. Lanchancea thermotolerans is a yeast that consumes simple sugars, but instead of producing alcohol, as per brewer’s yeast, it produces lactic acid, which causes the sour flavour. After approximately four days, we added our standard ale yeast to the now soured wort, which converted the rest of the sugar to alcohol.
Fruit was added both at the start, along with the Lanchancea yeast, but the majority was added immediately post-fermentation. The sugar in the fruit then started a short secondary fermentation.
Fruit addition rate is 115g/L, the ratio of raspberry to gooseberry is about 75:25
Appearance: Very deep pink, tending towards red. Pours with a short-lived pale pink head
Aroma: Intense raspberry aroma dominates, alongside a less prominent sweet gooseberry aroma
Mouthfeel: Medium carbonation lifts the sweetness of the fruit. Both lactic and citric acids hit the back and sides of the tongue
Flavour: Fruits dominate, with tartness present from the sour wort but also from the natural fruit sharpness. Sweet and sour fruit gives way to more lingering acidic flavours in the aftertaste. Relatively dry finish makes the overall sensation refreshing and moreish. Little to no hop character.