High intensity ultrasound assisted extraction of oak compounds for accelerated aging of wines and whiskies

Aging of wines and whiskies in oak barrels is a timely and expensive process which could be reduced by acceleration. The purpose of this study is to identify if the use of high intensity ultrasound (HIUS) assisted extraction as an alternative, accelerated aging method could be utilized in the production of an oak extract to be used in wine and whiskies. HIUS will also be compared to reflux and room-temperature control extraction treatments as other accelerated aging methods. Secondary objectives of this study were to compare the heat treatment of charred and toasted staves donated by an anonymous donor, their individual layers, and whether time had an effect on the extraction of color, total soluble phenolics, pH level, and oak compounds identified by gas and liquid chromatography from extraction treatments, heat treated oak staves, and individual oak stave layers. Analysis of variance and Tukey HSD showed that reflux extraction treatment extracted more color, total soluble phenolics, and ellagic acid than sonication or control extraction treatments; however, after 3 months, there was no significant difference among extraction treatments for extraction of color or total soluble phenolics. Results also showed that toasted staves had a higher availability of oak compounds than charred oak staves, but were similar for color, total soluble phenolics, pH, and various oak compounds after 3 months. Similarly, individual layers had a similar amount of each compound extracted over time, but had significant differences between layers such as charred and toasted inner-layers compared to charred and toasted outer layers. HIUS was found to be a viable and controllable accelerated, extraction method; however, reflux was shown to be more effective during this study. If future studies are done on the desirability of oak compounds, determination as to which method is a more effective method for production of an oak extract and the reduction of variability could change based on what compounds to include. A prepared oak extract utilizing desirable oak compounds would benefit the flavor and quality of aged wines and whiskies by reducing the time and cost of the aging process.