Traditional detoxification of acorn bread with clay

Parallel uses of clay in the traditional preparation of unpalatable acorns in California and Sardinia provide a case study for testing hypotheses on the detoxification function of geophagy. In laboratory simulations of the traditional methods, the addition of clays collected at the specific sites reduced the tannic acid digested from acorns by up to 77%. Reduction in tannic acid would make these nuts palatable and less toxic and provides a rational for the empirical practices. Adsorption and catalysis on clay surfaces are the most likely mechanisms accounting for the elimination of tannic acid activity.

Key words:

• geophagy
• pica
• dietary behavior
• detoxification
• clay
• tannins
• Quercus spp.