Controlled Environment Agriculture Increases Anthocyanin Content in Red Cabbage Microgreens

Objectives: Controlled environment agriculture (CEA) is a novel method of food production that can be leveraged for biofortification efforts. Red cabbage microgreens are rich in cardioprotective phytochemicals including anthocyanins (ACN) and glucosinolates, but ACN contents can be increased to enhance health benefits. Plant ACN production is responsive to environmental stressors such as temperature and light, and red cabbage microgreens suited to CEA biofortification. We hypothesized that ACN content could be increased in red cabbage microgreens, while maintaining crop yield and quality. Methods: Upon gemination, red cabbage microgreens were placed under an extended photosynthetic photon flux density (ePPFD; 400-750 nm) of 200 μmol·m–2·s–1 in walk-in growth chambers with an air temperature set point of 21°C. After 6, 8, 10, or 11 days, select microgreen trays were subjected to a reduced air temperature of 16°C. Harvest occurred 12 days post seed. Relative ACN and flavonol content were measured using a multiple wavelength pigment meter at the top of the leaf. Total phenolic content and total ACN were measured spectrophotometrically. Results: Transfer to 16°C after 6 days resulted in increased relative ACN compared to transfer after 11 days, and the overall greatest ACN content measured via differential pH (3.82 μg/mg dry weight). Transfer after 6 days also resulted in increased flavonol content, but reduced fresh weight compared to control (p< 0.05). Conversely, transfer to 16°C after 11 days resulted in no change in relative ACN content compared to the control, but increased total ACN as measured by differential pH (2.95 μg/mg dry weight) and increased relative flavonols while maintaining comparable yield to control (p >0.05). There were no differences between microgreens on day 10 and day 11 in yield, relative ACN, or relative flavonols. Conclusions: Next steps include further assessment of phytochemical profiling (e.g. glucosinolates) and bioavailability to support optimization of red cabbage microgreen nutritional quality grown under CEA without compromising crop quality and yield. Glucosinolate concentrations are also influenced by environmental stressors, and therefore are another target for CEA biofortification.