October 24, 2004

Vincent has been working with tequila distilleries in the Guadalajara area of Mexico.

Tequila is produced by fermenting the juice from the agave plant. Agave is a leafy cactus, like the yucca, aloe vera and century plants. It takes seven years to grow. At maturity there is a central fibrous ball from which the leaves grow. The leaves are discarded at harvest, and the central ball is transported to the distillery.

These balls are heavy and large, about two feet in diameter. There are two ways in which they can be processed.

Traditional processing calls for cooking the balls for 24 to 36 hours. This is done in steam chambers. Following cooking, the balls are run through large hammer mills, or hog mills. These shredders resemble those that is used at paper mills to chop tree trunks into chips.

The chipped agave is run through three or four stands of roller mills. These mills are small versions of the roller mills that are used for pressing sugar cane. Juice is forced from the agave in these roller mills. The juice is filtered, fermented and tequila whiskey is produced.

The largest tequila producer is Jose Cuervo. Their Los Camiches Distillery in La Laja uses diffuser technology instead of roller mills. The agave is not cooked. Instead it is simply shredded and fed through the diffuser. The diffuser is similar to a Crown Iron Works extractor, with the material conveyed by drag flight conveyers instead of trays. Hot water is sprayed from above. In its passage through the diffuser, Brix (dissolved sugars) in the agave are reduced from typical 20º degrees Brix to about 2° Bx. Upon leaving the diffuser, the agave is fed to screw presses, where the last moisture and dissolved solids are recovered.

The liquid from the diffuser, plus the press liquor, is filtered, cooked, and then fermented. The remaining fiber (press cake) is either composted or used as animal feed.

Testing with the Fiber Filter has proven unsuccessful due to the very fine nature of the fiber particles in the flows. However, screw press operations show much more promise.

Issue 166