Geosmin (2β,6α-Dimethylbicyclo[4.4.0]decan-1β-ol) Production Associated with Beta vulgaris ssp. vulgaris Is Cultivar Specific

Abstract

The characteristic earthy flavor and aroma of table beet [Beta vulgaris ssp. vulgaris (garden beet group)] is due to the presence of geosmin, C₁₂H₂₂O, a volatile terpenoid compound commonly produced by many soil microorganisms. This study screened beet and related subspecies cultivars grown in three different environments (field, greenhouse in nonautoclaved soil, greenhouse in autoclaved soil) to evaluate the effect of cultivar and environment on geosmin level in table beet. There was no significant difference between years or between cultivars grown in autoclaved and nonautoclaved soil, indicating geosmin content may not be primarily attributable to microbial associations. A significant interaction between cultivar and environment was found, but generalizations could be made for high- or low-producing cultivars, demonstrating that geosmin levels were cultivar specific. 'Bull's Blood', 'Chioggia', and sugar beet exhibited the highest geosmin levels. Cultivars grown in the field had the smallest range of geosmin production, from 4.84 to 20.82 μg geosmin (kg root tissue)⁻¹. The high degree of consistency in cultivar performance across years and in ranking for geosmin levels across environments as well as the lack of a significant difference between plants grown in autoclaved and nonautoclaved soil suggests characteristic levels of geosmin may be present in and produced endogenously by cultivars of table beet. It may be possible to establish breeding populations with defined geosmin levels and to identify variety-specific aroma and flavor intensities that would be durable across environments.