FERMENTATION AND COFFEE, PT. 2
Let’s talk through a few more complex fermentation types that can offer interesting flavors, more control, and higher cupping scores - all of which can lead to a bigger payday for the producer.
Controlled fermentations are becoming increasingly common. Very basically, a controlled fermentation is done by introducing a specific strain of bacteria or yeast to the fermentation process or encouraging the dominance of a specific strain. We can know exactly what microorganism acted on the coffee during controlled fermentations. Think about fermentations you may have tone at home like beer or kimchi: with beer, we introduce certain strains of yeast although we can utilize the natural yeasts in the air. With kimchi, we salt the cabbage to encourage the dominance of Lactic Acid Bacteria, although the cabbage would ferment on its own. Introducing a strain of bacteria or yeast to the fermentation tank is especially useful in humid areas with high rainfall (ex. Colombia), which could encourage the growth of mycotoxigenic filamentous fungi (dangerous, toxin producing molds).
So-called “anaerobic” coffees are pervasive in modern shops, but what does that actually mean? It requires a bit of science to understand. All microbes gain energy from either respiration or fermentation. When oxygen is not available, microbes will switch from breaking the strong chemical bond between two oxygen molecules that releases a lot of energy (respiration) to the much weaker bonds contained in sugars (fermentation). All fermentation is anaerobic; therefore anaerobic fermentation in coffee is a bit of a misnomer. Excluding the oxygen from the fermentation tanks either by sealing them in barrels or flooding them with water merely encourages more strict fermentation rather than respiration and fermentation, as happens in traditional open-air tanks. This means that the primary benefit of anaerobic fermentation in coffee is control, rather than flavor additives. Flavor development from anaerobic fermentation is the result of this high degree of control over the process.
Co-fermentation is a relatively new field in specialty coffee. It involves adding something to the fermentation tank with coffee, typically fruit pulp or spices. It can lead to some truly wild flavors - and as a result it’s quite polarizing. Co-fermentation represents the customer dictating the flavors desired rather than the producer. This is a controversial viewpoint, however it’s worth nothing that whatever adds value to the producer’s product (coffee) is beneficial. Whatever earns more money for them is not something to dismiss out of hand. Common co-ferments include passionfruit, cinnamon, name, lemongrass, and various other fruits often grown at origin. Blends are often made featuring one or more co-fermented coffees to create specific flavor profiles.
Kenyan Double Fermentation is a region-specific type of fermentation that is widespread in Kenya. Many washing stations dry ferment their coffee as a first step. next the coffee is soaked or passed through a washing channel using fresh water. A fair bit of evidence shows that this second washing step improves cup quality, but little research has been done into how exactly this takes place. Some producers disagree on the value of the soaking step as it does lead to a 1-1.5% weight loss.
Remember that:
All coffee is fermented.
Fermentation is used to break down the mucilage surrounding the coffee seed.
Fermentation adds flavor.
I hope that this will expand your palate and experience not just in coffee, but in all kinds of food and drink inside and outside the shop.