Coffee is Fermented, and what it taught me about pickling

Until last night, I didn't know coffee was fermented(-ish), but I certainly wasn't expecting to learn why fermented pickling works.

• Fermentation
• Coffee
• Food Science
• Pickling

Last night I watched the video above. I didn’t realize that fermentation was used at all in the process of producing coffee, and I certainly wasn’t expecting it to be used the way it actually is: it’s not really used to change the flavors of the coffee “bean”, but to remove sugars and moisture from the fruit and seed before it is dried and sent on its way to develop its true flavor profile. It was a fascinating watch and I highly recommend it to anyone who wants to know where coffee comes from (James’s channel is a great resource in general for that.)

But my main takeaway actually had nothing to do with the coffee. While discussing the different ways that coffee seeds could be fermented to remove the remaining layers of fruit, they mentioned how a salt brine like what is used for pickling actually “filters” the microbes that thrive in the jar with the vegetables.

All vegetables (in fact, everything in nature) has tons of microbes crawling the surface: molds, wild yeasts, bacteria (like lactobacillus), etc. and if we just left a vegetable in water, everything would multiply and feed and we’d end up with an absolutely rotten vegetable. However, the goal of pickling (as I describe in Is Quick Pickling Really Pickling?) is to reduce the pH (increase the acidity) to preserve the food.

The acidity itself will kill or significantly decrease the activity of the “bad microbes”, so there are a few ways to accomplish this: addign acid directly (quick pickling), lactic acid fermentation by “inocculation” (dumping a bunch of lactobacillus into the pickling brine to crowd out the bad microbes before they can create colonies), or find a way to encourage lactobacillus and discourage the other microbes naturally.

As it turns out, lactobacillus is perfectly happy in a salty solution and won’t turn the food rancid or start it decomposing. Meanwhile all the other bacteria, yeasts, etc. don’t do well in salty environments (this is why salt is also a common curing agent for meats). This means that essentially what happens when you pickle a vegetable is the salt in the brine filters out everything except lactobacillus, which reduces the pH of the brine (increases the acidity). The acidic brine then more effectively extracts the flavors from whatever pickling spices you used and infuses them into whatever you’re pickling. The acidity also further kills off or discourages the propagation of any microbes that might cause the food to spoil.

There are also a couple other aspects of fermented pickling and the recommended setup for doing so that improves the shelf life of the pickle, but I found it fascinating how the salt brine and the acidification through fermentation were linked. The salt isn’t just for flavor; it’s an integral part of making the process work properly.

All thanks to a James Hoffman video about how fermentation is used in coffee production.