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cool and inoculate it with wild yeast blown in on the wind. Our coolship is a converted, 115-year- old, 12-square-metre wine tank. We pump the wort straight into the tank, and the steam and wind carry in yeast overnight as it cools. e next day the cooled wort is transferred into large French oak barrels, where fermentation slowly begins. Most beers have primary and secondary fermentation stages. ese spontaneous beers undergo at least ve separate fermentation stages with numerous families of yeast and bacteria active throughout the total ageing time. We found dozens of di erent strains living in our version when analysed in a lab. STAGES OF FERMENTATION Initially, as the wort cools, Enterobacteria and oxidative yeasts are most active and this continues for the rst few weeks. Slowly, as the pH drops and the yeast grows, brewer's yeast – Saccharomyces cerevisiae and perhaps Saccharomyces pastorianus – begin to dominate, consuming the sugars and producing ethanol. Over months this stage slowly transitions into an acidi cation phase by Lactobacillus, Pediococcus and acetic acid bacteria. is acidi cation can go on for years, and is accompanied by the maturation phase, where the wild yeast Brettanomyces is most active, consuming any remaining carbohydrates and producing dry, funky avours. is stage of fermentation and acidi cation can go on for three or four years. Finally, these beers are blended and conditioned in the bottle before being released. THE ART OF BLENDING Blending enables the brewer to realise a beer’s nal vision. Blending is an art that demands creativity and experience. It takes a lot of trial and error. Each vintage is created with the goal of making the perfect beer, and no two vintages are exactly alike. A traditional blend can include many vintages. Typically, a nal blend is developed in many layers. Individual barrels usually have polarising avours; some barrels may be super sour, or some very phenolic and dry, while others may give an interesting fruity dimension. A brewer sees them working together to create a complete sensory experience with balance and nesse. When we blend, we generally designate barrels as sour, fruity, funky/dry or not ready. For Spontaneous Ale of Origin, we evaluated 11 di erent barrels, settling on six for the nal blend. Some barrels may even contribute as little as 5% of the nal volume but still have a large impact. Spontaneously fermented beers are some of the most amazing in the world. Few styles match their intensity, complexity and heritage – the key traits of a great beer. To try spontaneously fermented beer, keep a look out for any authentic Belgian Lambics at specialty beer stores. You can also check out Aegir Project’s Little Rouge, or join us for the release of Spontaneous Ale of Origin on Oct 16 th . YOU’VE READ THE ARTICLE NOW TASTE THE BEER! Spontaneous Ale of Origin launches at Soul Barrel’s taproom in Simondium on 16 October. As well as the new launch, there will be live music, barrel tastings, food pairing and a chance to create your own blend. ontapmag.co.za | Spring 2021 | 49 100+ Types of Base and Specialty Malts +32 (0) 87 662 095 www.castlemalting.com info@castlemalting.com Organic malts