Made in Kuldīga: what a slow ferment does that a factory line does not

Kuldīga sits on the Venta in Kurzeme, western Latvia. Rudy's Brewing Co brews at Tehnikas iela 2B, and the address on the certificate is the address the cans come from. Fermenting, blending and filling happen under one roof rather than being handed between a brand, a brewery and a filling plant. That is not a virtue on its own. It is the reason the rest of this page can be specific: when one building does all three steps, someone inside it can tell you what happened in each of them.

Fermentation is the slow step and there is no way to buy it back. Sweetened green tea goes to the culture, and over days the culture works through the sugar and produces the organic acids, the carbon dioxide and the trace of alcohol that make the drink what it is. Time is the one input that cannot be optimised out without changing the result, because the tartness and the fizz are what that time leaves behind. We do not print a day count on this page: it varies by batch and by flavour, and a single tidy number would be a rounder story than the truth.

The first two lines of every ingredient list are water and kombucha culture, and the certificate spells the culture out as water, green tea and a SCOBY. Then fruit, at a printed percentage: pineapple juice 20 per cent, raspberry juice 12 per cent, rhubarb juice 12 per cent, mandarin juice 10 per cent, passion fruit juice 7 per cent, mango puree 6 per cent, ginger 4 per cent, pear puree 2.5 per cent. Then plant fibre from maize and chicory, 1.6 grams per 100 ml in every flavour. Then a named sweetener. No colour, no stabiliser and no preservative appears on any of them.

Every certificate carries the same line: the batch number is shown by the best-before date, printed in dd.mm.yyyy. There is no separate code to hunt for on the base of the can. That date is what the brewery's own records are keyed to, which is what makes a question about one particular can answerable. Each batch is also tested before it leaves: coliforms not detected in 3 ml by GOST 31747, moulds under ten colony-forming units per millilitre by LVS ISO 21527-2, salmonella not detected in 25 ml by LVS EN ISO 6579-1. The method names are on the certificate too.

Every Rudy's is a 330 millilitre aluminium can, sold in nines. Aluminium is opaque, which keeps daylight off a drink that is still alive, and the storage line on the label assumes exactly that: +2 to +25 °C, out of direct sun, 365 days. Because the culture is still working in there, a can kept warm for a long time keeps fermenting, turns more sour and holds more pressure. That is the drink doing what it does rather than a fault - chill it before you open it, and open an old one over a sink.

Nine core flavours carry a published certificate: Lemon & Ginger, Matcha & Passion Fruit, Pear & Fireweed by Madara Meiere, Rhubarb, Raspberry & Basil, Mango & Passion Fruit, Mandarin & Yuzu, Coconut & Pineapple and Pineapple & Peach. Beside them sits Hard Kombucha: the same ferment taken further with champagne yeast to 4.5 per cent alcohol by volume, in Passion Fruit, Guava and Mandarin & Yuzu. Hard is an alcoholic drink and is sold to adults 18 and over only. The kombucha took gold at the World Kombucha Awards in 2023 and again in 2025; the Hard range took an innovation award at SIAL Paris in 2022.

Rudy's began in 2019 in a ten-litre bucket in a walk-in closet - a couple, the idea that kombucha should taste of fruit rather than vinegar, and a dachshund called Rudy who ended up giving the company its name. It is now fifteen people in a thousand square metres, sending cans to sixteen countries. Small enough that a batch has a person attached to it, large enough to keep nine flavours in stock at once. Both halves of that sentence matter, and only one of them is something a factory line can offer you.