Computational Modeling of the Heat Treatment of White Oak Bound for Spirit Maturation

Maturation of distilled spirits in white oak barrels is a long standing practice known to have great impact on spirit character. Much of this impact can be controlled by the thermal modification of the barrel, since thermal degradation of the wood determines what wood compounds are available to interact with the spirit during maturation. In this work, a computational model for the thermal degradation of wood was developed and, with flavor compound data from literature, was used to investigate the effect of heat treatment on lignin-derived flavor compounds. The computational model in this work accounted for three solid species, three gas species, momentum conservation, and energy conservation. The kinetic scheme for wet wood decomposition included three primary and two secondary pyrolysis reactions, the evaporation of moisture, and the condensation of water vapor. The computational model was verified against another numerical model for wood pyrolysis from literature. The temperature results of the computational model were processed with data for seven lignin-derived flavor compounds. A test case matrix for hypothetical barrel heat treatment levels was investigated. Conclusions from the test cases were that barrel toasting increases the total amount and distribution width for all compounds examined.