Wild strawberries have an intense aroma and sweet taste. However, wild strawberries are rare and expensive, so synthetic versions of this flavor are useful. Some species of fungi can convert plant material into flavor compounds. The brown-rot fungus Wolfiporia cocos, for example, can break down a variety of foods and release fruity and floral aromas in the process. An abundant and nutrient-rich substrate for the fungus could come from blackcurrant juice production, which leaves a waste known as pomace (skins, pulp, and seeds).

Holger Zorn, University of Gießen and Fraunhofer Institute for Molecular Biology and Applied Ecology, Gießen, Germany, and colleagues have grown W. cocos on pomace from blackcurrants and optimized the conditions to produce wild strawberry aroma for the food industry. The researchers initially grew the fungus with blackcurrant pomace as the sole source of nutrition, which resulted in fruity and floral aromas. When the team added sodium L-aspartate, the culture released an aroma similar to wild strawberries.

To pinpoint the exact compounds that contributed to the scent, the researchers used gas chromatography-mass spectrometry-olfactometry (GC-MS-O), with ten trained panelists assessing the scents. The most intense odors that the sensory panel perceived were (R)-linalool, methyl anthranilate, geraniol, and 2-aminobenzaldehyde. The researchers then combined artificial versions of these four compounds into a model wild strawberry smell and found that the sensory experts rated it as being very similar to the wild strawberry-like odor from the cultivated fungus. Growing W. cocos on food waste might provide a sustainable and cost-effective way to produce a wild strawberry-like aroma that could be used industrially.

• Wild Strawberry-like Flavor Produced by the Fungus Wolfiporia cocos─Identification of Character Impact Compounds by Aroma Dilution Analysis after Dynamic Headspace Extraction,
  Svenja Sommer, Marco A. Fraatz, Julia Büttner, Ahmed A. Salem, Martin Rühl, Holger Zorn,
  J. Agric. Food Chem. 2021.
  https://doi.org/10.1021/acs.jafc.1c05770