Coffee Fermentation: Reasons To Add Microorganisms

Fermentation is a process that takes place during any coffee processing. It is started by microorganisms that are initially found on berries, equipment walls, in water and air. As a result of their vital activity, decomposition products of sugars, organic acids and other metabolites are formed. The fermentation medium becomes more acidic.

The problem is that the fermentation process is difficult to control. The farmer can only control external factors: regulate temperature, lighting, humidity and oxygen. But farmer does not always know which microorganisms are presented on coffee berries and equipment. Therefore, it is hard to know for sure what characteristics the coffee will have after fermentation.

However, the expected result can be obtained if a certain type of microorganism is used.

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One way to control fermentation is to add certain lab-grown strains of bacteria, yeast, and fungi. This will help strengthen the descriptors as well as control the process and reduce the fermentation time.

Cellulase and Aspergillus (enzyme and fungus) help prevent the formation of toxins and speed up the fermentation process. The aspergillus enzyme dissolves the cellulose and the fungus consumes the substances in the bean. As a result, reducing sugars are formed (a certain type of sugars that are involved in caramelization and Maillard reactions). They also have a positive effect on the aroma of coffee.

Lactic acid bacteria Lactobacillus play an additional role in the formation of the coffee taste and aroma. Lactic bacteria use citric acid and amino acids as an energy source for fermentation.

Metabolism of citric acid leads to the formation of diacetyl and acetoin, compounds that contribute to the buttery taste of fermented milk products. Aromatic compounds are formed from amino acids. Some compounds, such as esters, ketones, higher alcohols, and aldehydes, are able to permeate the bean and form floral and fruity flavors.