Introduction to the difference of flavor and taste between carbon dioxide impregnated coffee beans and anaerobic treated coffee beans

One of the rapidly popular new processes that can produce an incredibly unique flavor involves anaerobic fermentation, which is called carbonic acid impregnation. Let's first break down the terminology here so as not to get caught up in the details.

Anaerobic-anaerobic environment

Carbon dioxide-an environment rich in carbon dioxide

Impregnation, a more inclusive term than fermentation, refers to microbial metabolism

In a sense, anaerobic and carbonic acid can be used interchangeably-both refer to limited oxygen. You may also notice that the scientific definition of fermentation includes the word "anaerobic", so the word "anaerobic fermentation" is superfluous in a sense. To be clear, even if there is oxygen in the environment around the fermentation microorganism, it will not be used in a specific fermentation process. This is not to say that aerobic impregnation did not occur; it is true, because many microbes like oxygen and can digest coffee fruits. This is why these terms do make sense in the context of coffee. Since we have been talking about the limited ways in which coffee can be fermented for a long time, we need to be more specific when the usual process changes. Throughout the history of washed coffee production, the period of impregnation of starched coffee-usually in open-air cans or buckets or even plastic bags-has been called "fermentation". Its origin is function, not form. This is just a method used by farmers to remove sticky fruit mucus from parchment-covered coffee seeds. Although the flavor change is important, we mainly get rid of fructose and pectin.

Now we are looking at the complexity of microbiology and its effect on flavor, and more precise terminology is needed to help distinguish whether farmers are traditionally fermenting or using more specific methods. As a result, the rise of "anaerobic" fermentation in coffee. When coffee farmers use the word, they usually mean that they have created a sealed environment. Usually, the coffee is beaten as usual, and then the mucus parchment is put into a sealed can, usually a stainless steel can, with a valve to allow exhaust. In some cases, this fermentation may extend the traditional time of 12-36 hours by hours or even days. The types of microorganisms that can survive and actively participate in fermentation are limited by hypoxia in the air and may significantly change the final flavor characteristics. The anaerobic coffee I've tasted recently has incredibly accurate and immediately recognizable flavors such as gingerbread, cinnamon, licorice, bubblegum or boiled pears. The taste is often single, highly expressive and unusual. The main factor that distinguishes anaerobic coffee fermentation from carbonic acid impregnation is that in carbonic acid impregnation, cherries remain intact and are not pulped before entering the sealed tank. Carbon impregnation is a term extracted from the wine industry in which whole grapes are fermented without squeezing juice. This tends to produce fresh fruit-flavored wines that may not age well but are ready to drink soon after production. In the carbonation process of coffee fermentation, the coffee fruit is first siphoned to remove low-density "floating matter" and then added to a closed tank with an one-way valve, which is very similar to the anaerobic method. As the cherry skin is intact, it may take days or weeks to ferment. Different degrees of pressure in the tank will produce different available sugars and pectin for microbial impregnation. Near the bottom of the pot, the coffee is gently squeezed by gravity over time, while the cherries near the top of the pile remain unpressed, and the fermentation will be slow and almost entirely in the skin of the fruit.