Profiling the volatile metabolomics and aroma characteristics of Chinese oak-aged whisky: insights of the toasting and charring effects on oak

Abstract

Oak plays a significant role in shaping the distinct whisky flavor. In this study, oak blocks from China (Q. mongolica), France (Q. robur), and America (Q. alba) with different toasting degrees and charring intensities were applied in the maturation of whisky for 9 months, respectively. Volatile compounds and aroma characteristics in aged whisky were investigated. Results showed that whisky aged with Chinese oak had higher concentrations of volatile phenols, with o-cresol being 2.97 times higher than that in American oak, and 7.47 times higher than that in French oak, contributing to a stronger perception of 'smoky' notes, but lower concentrations of furanic derivatives and oaklactones than whisky aged with French and American oak. Oak toasting degrees had a greater impact on whisky aroma than charring intensities, especially on oak-derived volatile compounds. The selection of the proper charring intensity could be determined by the initial concentration of oak-derived volatile compounds in the uncharred oak, such that for oak wood with high aromatic potential, excessive charring would rather lead to a reduction in the oak aroma. The process of light toasting combined with mild charring could promote the accumulation of volatile phenols in Chinese oak, thereby contributing to the formation of distinctive characteristics in whisky. This study offers whisky producers guidance on using Chinese oak to enhance 'smoky' flavors, and create distinct regional whisky styles.

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