What is Mountain Water Process decaf?

The Mountain Water Process (MWP) is a water-based decaffeination method using pure spring water from Mexican glaciers (Sierra Madre Occidentale), without chemical solvents. Developed and operated exclusively by Mexican company Descamex, it works on the same osmotic principle as the Swiss Water Process, with the distinguishing feature of using high-purity, low-mineral water as the decaffeination agent.

The Mountain Water Process was born in Mexico and is operated by Descamex (Descafeinadores Mexicanos, S.A. de C.V.), a company founded in 1972 in Córdoba, Veracruz. The Córdoba region is one of Mexico's most important coffee growing and processing zones, which naturally led to the development of a decaffeination industry there.

The MWP process is fundamentally similar to the Swiss Water Process in its logic, but with some implementation differences. First, the water used comes from glacial sources in the Mexican Sierra Madre Occidentale, renowned for their purity and very low dissolved mineral content (oligomineral water). Descamex presents this purity as an advantage in avoiding unwanted interactions between water minerals and coffee compounds.

As in the SWP, the process relies on creating a Green Coffee Extract (GCE) saturated with aromatic compounds but stripped of caffeine, then immersing lots to be decaffeinated in this extract. Caffeine migrates out of the beans by osmotic diffusion over 8 to 12 hours, while aromatic compounds remain in the bean due to concentration equilibrium.

A notable difference from the SWP is the specific geographic origin — the MWP is often presented as a 'Mexican terroir' product, which resonates well with the origin and traceability values of specialty coffee. Descamex also offers organic certification for its MWP lots, making them compatible with organic decaf coffees.

MWP is less universally known than SWP, but it is appreciated by some roasters seeking an equivalent-quality alternative with different origin traceability. For the end consumer, the organoleptic difference between an SWP and an MWP coffee from comparable origins is generally imperceptible — both preserve the main aromatics of the base coffee well.

In practice, the reputation of a quality MWP or SWP decaf rests above all on the quality of the green coffee chosen for decaffeination, and on the freshness of the roasting.

Swiss Water Process vs Mountain Water Process