Aroma and metabolite profiling in duckweeds: Exploring species and ecotypic variation to enable wider adoption as a food crop

Duckweeds (water lentils) are a nutritious human food source, with Wolffia species consumed traditionally in Eastern Asia. Duckweed contain up to 45 % protein by dry weight, high macronutrients, minerals and carotenoids. However, duckweed are not cultivated at scale and there are circa 35 other species to consider for food potential in other global regions. Here, we measured the suitability of four Lemna species and Spirodela polyrhiza for nutritional assessment, by scaling up growth of 25 ecotypes from the United Kingdom in a glasshouse. Here we showed intra- and inter-species variation of aromatic and metabolic profiles, together with biomass obtained from production. The dominant volatile organic compounds (VOCs) in duckweed are hexanal, 1-penten-3-one, 1-penten-3-ol, cis-2-pentanol and pentadecanal, with variations in amounts of 22 other compounds between species. In comparison with other leafy herbs, duckweed aroma profiles were most similar to spinach and dandelion with high ‘green’ and ‘fresh’ aroma compounds. Spirodela polyrhiza contained high flavonoids including apigenin and luteolin, offering potential benefits for health. Our results demonstrate that Lemna and Spirodela species have suitable flavonoid and amino acid profiles for nutrition. VOCs found here had positive aroma descriptors and can be used as biomarkers of freshness during storage of duckweed foodstuffs.