Colombian coffee: wet or dry pulping?

Traditionally, the fermentation process for pulping coffee beans has been used. It begins by soaking the beans and then removing the water, which carries the hydrolyzed mucilage; this is a natural process in which the flora in the coffee bean hydrolyzes the carbohydrates in the mucilage and turns them to water-soluble compounds. The issue here is that, in the washing stage, these compounds remain in the water as dissolved solids contaminating it, so huge amounts of water are required for washing. The fermentation process, although a natural one, has always posed two serious issues: water consumption and contamination. If carefully performed, the process yields a very clean cup without fermentation traces. It is argued that the water solves some of the coffee components and washes them away, making it lose some cup characteristics, although there is yet no  formal evidence.

Mechanical equipment has been introduced for pulping, using a lot less water in much less time; the mucilage can be contained and later used as organic fertilizer. There are hazards, however. If the machine is not finely tuned and very clean the mucilage may not be completely removed; handling must be careful to avoid fermentation and fungi. Additionally, non-ripe beans are difficult to remove and this might end up spoiling the cup.

There is a discussion on the effects of the processes on cup characteristics. A good cup is always the result of care and control in all the processes. Good selection, control of operations flow to avoid delays or stagnation in the processes, careful handling, sparkling clean equipment and facilities and stringent quality control always end up producing excellent cup characteristics.

The truth is that either system (fermentation or mechanical), if carefully performed, can yield a very good cup.

For small batches, contamination from the fermentation process can be managed and controlled, but with large amounts of coffee, contamination can become a serious -and expensive- problem.

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