Would Less Earthy Aroma Make Beets Taste Better?

Geosmin is a compound associated with the earthy aroma of beets. Does reducing it, then, produce beets that people like better?

A participatory plant-breeding study published in 2022 found that the answer was not so simple. Consumers accepted both low- and high-geosmin lines, and concentration alone did not consistently explain whether people found them earthy or liked them. The project also incorporated the views of farmers, chefs, and consumers to develop five new cultivars.

From research on a molecule to breeding with growers and eaters

The study began with low- and high-geosmin populations. Both varied in root color, making them promising material for developing beets with distinctive flavors and appearances.

The aims were to develop cultivars suited to organic farms in Wisconsin, United States, that people would also enjoy eating, and to investigate responses to geosmin concentration outside the laboratory. The researchers compared a model involving one farm, its staff, and its customers with a model gathering input from multiple farmers, chefs, and visitors to tasting events.

Selection took place from 2016 to 2018, evaluating germination, disease resistance, growth competitive with weeds, root shape, and appearance. Willingness to eat the beets again also informed the first two selection cycles; the final year focused mainly on horticultural traits. Seeds were collected from selected roots to grow the next generation.

Evaluating steamed beets in settings closer to everyday eating

For tasting, whole beets were steamed for 20–22 minutes and cut into portions with their skins left on. Samples were coded, but their colors were not concealed. At farms, restaurants, and consumer events, participants evaluated willingness to eat again, appearance, and characteristic beet flavor. Across the first two consumer selection cycles, 120 people participated in the farm model and 119 in the broader outreach model.

In 2018 and 2019, some of the developed cultivars and comparison cultivars were also rated on five-point scales for sweetness, earthiness, bitterness, intensity, complexity, liking, and other attributes. In 2018, 38 consumers and seven chefs participated; in 2019, the participants were 38 consumers, nine members of a university horticulture department, and six chefs, at their respective venues.

Chemical analysis measured geosmin and total dissolved solids (TDS) in separately collected raw root samples. TDS is an indicator reflecting substances such as sugars. Geosmin was not measured in the steamed beets actually tasted, leaving uncertainty about volatilization during cooking and differences between individual roots.

Less geosmin did not determine the ranking of preferences

The starting populations differed clearly in geosmin concentration, but not significantly in mean TDS. Even with selection material that differed in geosmin, many selection events showed no strong differences in which groups participants wanted to eat again.

Across the first two cycles, 87% of consumer evaluations of low-geosmin groups and 85% of evaluations of high-geosmin groups indicated willingness to eat again. The difference was not significant. These percentages refer to pooled evaluations of multiple samples, not percentages of people. Material with very different concentrations of the compound was received positively in both cases.

After selection, the low-geosmin populations diverged in concentration between the two models. However, selection sometimes favored lower concentrations and sometimes higher ones, without clear preference differences at those selection events. The authors interpreted this as reflecting chance variation when retaining a limited number of parents, rather than consistent selection toward a preferred concentration.

Concentration alone did not explain perceived earthiness either

In the later cultivar evaluations, high-geosmin ‘Moving Target’ and ‘Blushing Not Bashful’ did not differ significantly in perceived earthiness from low-geosmin ‘Snowglobe’ at any tasting event. Conversely, cultivars without significant differences in measured concentration sometimes received different earthiness ratings.

The association between earthiness and liking also changed by year: it was negative in 2018 and weakly positive in 2019. Participants were not given aroma reference samples, so they may have associated the word “earthy” with bitterness, a lack of sweetness, or other attributes.

By contrast, greater perceived sweetness was significantly associated with greater liking in both years. Greater perceived bitterness was associated with lower liking in both years, but significantly so only in 2018. Although perceived sweetness differed between cultivars, TDS did not differ significantly: a sugar-related indicator could not fully explain perception either.

White beets sometimes exceeded expectations based on appearance

White-rooted beets provided an interesting example. During selection, one white group was selected for the next generation despite much lower appearance ratings than colored comparison groups, because its acceptance in terms of willingness to eat again was similar.

In later tastings, ‘Blushing Not Bashful’ belonged to the higher-ranking comparison groups for both sweetness and liking. This cultivar came from high-geosmin material. Reducing the compound associated with earthy aroma was not the only route to a well-liked cultivar.

The authors suggested that an unfamiliar white appearance may have lowered expectations, allowing the eating experience to exceed them. However, this was not an experiment changing only the color of the same sample. Another white cultivar was not consistently rated highly, so an effect of color alone cannot be established.

Five new cultivars, and the value of involving chefs

The study produced the low-geosmin cultivars ‘Evansville Ember’ and ‘Snowglobe’, and the high-geosmin cultivars ‘Evansville Orbit’, ‘Moving Target’, and ‘Blushing Not Bashful’. The last narrowly missed selection by consumers but was developed separately after chefs valued its flavor and appearance.

The authors concluded that chefs helped identify novel traits, while a network connecting farmers and consumers generated interest in cultivars during development. Each cultivar was selected at only one location, and there was no parallel comparison under conventional cultivation. Whether they perform well on organic farms in other regions therefore requires further testing.

Conclusion

In this study, which evaluated steamed beets in settings closer to everyday eating, lower geosmin alone did not consistently explain liking or earthiness. Perceived sweetness was associated with greater liking in both years, and some high-geosmin cultivars were well liked.

Selection involving farmers, chefs, and consumers produced five cultivars with different flavors and colors. The authors highlighted the importance of breeding with taste, aroma, appearance, and eating context in mind, rather than focusing only on reducing a single compound.

The study was supported in part by USDA Hatch funding. The developed cultivars are subject to commercial licensing through the Wisconsin Alumni Research Foundation, and authors Hanson and Goldman disclosed that they receive a share of the revenue.

Reference

Hanson SJ, Dawson JC, Goldman IL. Participatory plant breeding reveals that geosmin concentration is not the central determinant of hedonic liking in table beet. Euphytica. 2022;218:14. Original research article