AGGLOMERATION OF ETHYL-ESTERS IN MODEL SPIRIT SOLUTIONS AND MALT WHISKEYS

Medium- and long-chain ethyl esters were found to have a limited solub ility when model spirits and malt distillates were diluted to 230 ml e thanol per litre for sensory analysis. At concentrations above this cr itical level the concentration of esters in solution remained constant , with the excess esters forming agglomerates. The saturated nature of the solution reduced the volatility of other esters, with a proportio n of these compounds being partitioned into the agglomerate. The distr ibution was dependent on the mole fraction of each ester and its activ ity coefficient. Dissolution of wood extractives caused a number of ch anges in the solubility parameters of organic compounds; activity coef ficients were increased and both the concentration and activity at whi ch agglomeration occurred were decreased. This resulted in lower solut ion concentrations with increased concentrations in agglomerates. The reductions in free solution concentration could result in lower headsp ace concentrations, and thus have a direct effect on the flavour of th e matured spirit.