What is the meaning of lactic acid fermentation with coffee bean treatment?

In daily life, many delicious foods are produced by lactic acid fermentation, such as pickled pickles, yogurt, cheese and so on. In the process of raw bean processing of coffee, the operation of lactic acid bacteria will also be introduced in the fermentation process, so as to give the coffee a unique and complex flavor.

Lactic acid bacteria are a broad group of bacteria that convert carbohydrates, such as glucose, sucrose or galactose, into lactic acid. Under certain circumstances, they also ferment into ethanol. In this fermentation process, lactic acid bacteria will produce many flavor compounds (esters, ketones, aldehydes), which give food unique flavor and taste.

In recent years, with the continuous innovation of the special post-placement method of boutique coffee, more and more coffee estates begin to try to enhance their lactic acid fermentation (Lactic Fermentation) process to bring stronger floral and fruity aromas, as well as wine-like acidity and mellow texture.

As a facultative anaerobes, lactic acid bacteria can only be metabolized in an anaerobic or hypoxic environment, which happens to create such a relatively anaerobic environment in the pool soaking raw coffee beans. Therefore, in the past, lactic acid bacteria fermentation is common in the traditional water washing treatment, where the main participants are yeast and lactic acid bacteria.

At this time, the lactic acid bacteria will use the sugars in the coffee pulp as raw materials for fermentation, and the metabolic process can help remove the mucus layer, making the pectin easily detached, while providing bright acid for the beans. However, there is no limit to the number of bacteria that participate in fermentation in the pool, that is, both yeast and lactic acid bacteria.

In recent years, many studies have focused on the participation of lactic acid bacteria in fermentation. Studies have shown that some lactic acid strains can produce a variety of aromas, and positive lactic acid fermentation can enhance certain flavors in coffee and make drinkers have a better sensory experience.

Compared with yeast, lactic acid bacteria are more "tolerant" to anaerobic environment. Most yeasts can survive without oxygen, but once they have access to oxygen, they multiply much faster. However, the amount of oxygen has little effect on the reproduction rate of lactic acid bacteria, so many producers will produce hypoxic fermentation in order to increase lactic acid fermentation and limit the growth of yeast.

If you want to get effective and controllable lactic acid fermentation, the best way is to add lactic acid bacteria directly to the controlled fermentation. As long as enough specific strains are added to the fermentor, there is a chance to make lactic acid bacteria "pre-emptive" and dominate the whole fermentation process. However, this approach also has a disadvantage, that is, the cost is too high, because the culture cost, packaging cost and transportation cost of active lactic acid bacteria are much higher than yeast bacteria.

It is understood that the idea of lactic acid fermentation in the processing of raw coffee beans was put forward relatively early, which is Colombia's Palm Tree and Big Bird Manor (La Palma y El Tucan). The founders of the estate, Felipe Sardi and Elisa Madrinan, specialize in innovative projects, using anaerobic methods to make coffee produce higher concentrations of lactic acid bacteria during fermentation. Fermentation as a variable, using different sealed containers for treatment, to achieve operational variable control, so that their beans have a strong sweetness and thick sense of fermentation.

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