Fermentation in coffee processing, refers to the chemical breakdown of the sugary mucilage layer surrounding the coffee bean, which naturally occurs in water.
For the fermentation process within the fully washed method, three five gallon buckets were used to hold the water for each of the three varieties, and once water had been added to the parchment in each of the tanks, they were placed on the patio to begin fermentation.
They would remain there from 12:45 pm until 5:30 pm, at which point they were brought into the El Manzano laboratory, in order to maintain a consistent temperature throughout fermentation.
Beneficio El Manzano is located at an altitude of over 1300 meters, and therefore has the potential to slow down fermentation, due to the colder temperatures during the night, which reduce the temperature of the water within the fermentation tank.
Throughout the fermentation process, (excluding the period of time from 11:00 pm to 7:00 am), the parchment was stirred once every hour, and monitored for amount of mucilage remaining on the bean.
At the start of fermentation the water is very clear, and the beans very slimy. Over time, and into the following morning, the fermentation tanks reveal a courser parchment and thicker, dark colored water.
“The end of the fermentation is assessed by feel, as the parchment surrounding the beans loses its slimy texture and acquires a rougher "pebbly" feel” (http://www.ico.org/field_processing.asp).
“Currently, the best way of determining the end of coffee fermentation is to feel the coffee beans to determine if they are still encased in mucilage” (www.coffeeresearch.org).
Showing the earliest signs of effective, complete fermentation was the yellow bourbon, and at 8:45 am, the parchment was strained and rinsed lightly, spread out on the patio to dry.
Of all of the varieties, the mucilage of the yellow bourbon dissolved the quickest, with a total time of fermentation at 20 hours.
(One note to make would be that this sample was the smallest, and therefore contained a smaller amount of water, and spread a thinner layer at the bottom of the tank. Otherwise, there is no genetic evidence that we know of, to cause one to say that this variety’s mucilage dissolves quicker than the others because of genetic qualities. All we can make is observations.
Fermentation could take or last anywhere from 24-36, however considering the warmer sunny conditions, and well monitored and stirred beans, 20 hours is not too short of a period for fermentation. Fermentation times of longer than 36 hours however, can cause problems affecting the final cup quality of the coffee.
“If the coffee beans are fermented for 36-72 hours, stinker beans develop” (www.coffeeresearch.org).
The Red Bourbon and Pacamara would soon follow, as their mucilage soon completely dissolved, and they were similarly rinsed and spread out onto the patios at 10:15 am and 11:15 respectively, bringing their total fermentation times to 22.5 and 23.5 hours.