What is a starter (in coffee processing)?
A starter is a culture of yeast or bacteria introduced into coffee fermentation to guide the process in a particular direction. Instead of relying only on the naturally occurring microbes on the coffee cherries or in the environment, producers can add a starter to create more control and consistency.
Starters can be made from commercial strains, or developed locally from fruits, plants, or even previous fermentations. The chosen microbes affect how sugars and acids break down in the coffee, shaping flavour development in the cup. Using starters can help producers highlight fruity, floral, or clean profiles, and sometimes reduce unwanted defects that might occur in uncontrolled fermentations.
This approach is part of a wider trend towards experimental processing, where fermentation is treated as a tool to fine-tune flavour rather than just a step in removing the mucilage.