RELATIONSHIP BETWEEN FREE AND COMPLEXED FORMS OF COPPER IN MALT WHISKEY DISTILLERY SPENT WASH

Abstract
The spent wash produced by an Irish malt whiskey distillery was sampled over a four-year period. Total soluble copper levels of up to 8·5 ppm were found; these varied with wash pH. No more than 6% of total soluble copper was present as the free ion; the level varied with wash pH as well as with its free amino acid and total soluble copper content. However, up to 83% of total spent wash copper was in an insoluble form associated with its suspended solids.