Light source and spectra influence the phytochemical profile of amaranth microgreens

Authors: TRANDEL-HAYSE, MARLEE - Auburn University; Bai, Jinhe; Jeffries, Kristen; POOLE, GAVIN - North Carolina State University; Hensley, Michael; Schonborn, Wesley; DIGIOIA, FRANCESCO - Pennsylvania State University; Rosskopf, Erin

Submitted to: Food Bioscience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/2/2025
Publication Date: 1/2/2025
Citation: Trandel-Hayse, M., Bai, J., Jeffries, K.A., Poole, G., Hensley, M.E., Schonborn, W.A., Digioia, F., Rosskopf, E.N. Light source and spectra influence the phytochemical profile of amaranth microgreens. Food Bioscience. 64:105839. 2025. https://doi.org/10.1016/j.fbio.2025.105839.
DOI: https://doi.org/10.1016/j.fbio.2025.105839

Interpretive Summary: Microgreens are a form of vegetables that are nutrient dense and easy to grow. As interest in microgreens grows, there are numerous production parameters that can be modified to influence yield, quality, and nutritional value. There is great interest in understanding how LED light spectrum affects the quality and nutritional profile of microgreens. In this study, amaranth microgreens were cultivated under controlled environment using various light conditions: sole source LED red:green:blue (R:G:B) at different ratios compared to white (W) or ambient light. Microgreen samples were extracted and analyzed for flavonoids, carotenoids or widely targeted metabolomic profiling. Comprehensive analyses revealed the presence of nine vitamins, six carotenoids, 19 flavonoids, 22 amino acids, five nucleosides, five sugars, and four organic acids in the microgreens. When grown under R:B with or without G, the microgreens exhibited remarkable enhancements in redness, and tender texture. Notably, these microgreens contained higher levels of vitamin E, vitamin C and carotenoids, but lower levels of flavonoids and B vitamins. Microgreens grown under R:B also demonstrated increased sugars and acids compared to W and ambient light. However, amaranth cultivated under R:B and R:G:B exhibited a decline in most amino acids and nucleosides, which are known to contribute to rich and complex flavors. This study indicates R:B and R:G:B do not stimulate increased phytonutrient production in amaranth.

Technical Abstract: Radiation level and spectrum are important drivers for plant primary and secondary metabolism. There is great interest in understanding how LED light spectrum affects the quality and nutritional profile of nutrient-dense crops such as microgreens. In this study, amaranth microgreens were cultivated under controlled environment using various light conditions: sole source LED red:green:blue (R:G:B) at ratios of 70:10:20, R:B at 80:20, white (W), or ambient light. Microgreen samples were extracted and analyzed for flavonoids, carotenoids or widely targeted metabolomic profiling via LC-MS/MS. Comprehensive metabolomic analyses revealed the presence of nine vitamins, six carotenoids, 19 flavonoids, 22 amino acids, five nucleosides, five sugars, and four organic acids in the microgreens. When grown under R:B with or without G, the microgreens exhibited remarkable enhancements in redness, and tender texture. Notably, these microgreens contained higher levels of vitamin E, vitamin C and carotenoids, but lower levels of flavonoids and B vitamins. Microgreens grown under R:B also demonstrated increased sugars and acids compared to W and ambient light. However, amaranth cultivated under R:B and R:G:B exhibited a decline in most amino acids and nucleosides, which are known to contribute to rich and complex flavors. This study indicates R:B and R:G:B do not stimulate increased phytonutrient production in amaranth.