(P23-016-25) Biofortification of Red Cabbage Microgreens Under a Reduced Temperature Growing Environment

Objectives: Microgreens are rich in nutrients and phytochemicals and gaining popularity with consumers. They are grown indoors, and we have demonstrated increased anthocyanin contents in red cabbage microgreens grown under reduced temperatures. However, manipulation of the growing environment can be costly, which may be impractical for some producers. We hypothesized that leveraging existing equipment (i.e., walk-in coolers) to reduce temperatures to 4°C for 24 hours at the end of production would have a similar effect previously observed with reducing temperatures to 16°C for 4 days in a growth chamber environment.

Methods: Red cabbage microgreens were germinated in the dark at 26°C for 4 days. Upon germination, air temperature was decreased to 21°C and an extended photosynthetic photon flux density (400-750 nm) of 200 µmol∙m^–2∙s^–1 over a 16-h photoperiod was provided. Microgreens trays either remained at 21°C (control) or were transferred to a separate growth chamber environment (12°C) on day 8 or 11 or a walk-in cooler (4°C) on day 11. Microgreens were harvested 12 days after sowing. Relative anthocyanins (ACN) and flavonols were measured using a multiple wavelength pigment. Total phenolics were measured using a Folin-Ciocalteu assay and total ACN were measured using differential pH absorbance.

Results: Microgreens transferred on day 11 to both 12°C and 4°C had a similar fresh weight compared to the control, while transfer on day 8 to 12°C significantly impeded yield (p < 0.05). Microgreens transferred on day 8 to 12°C and day 11 to 4°C increased relative ACN, while only those transferred on day 8 to 12°C showed an increase in relative flavonols compared to control (p < 0.05). All cold temperature treatments increased total phenolic contents compared to control (p < 0.05 for transfer on days 8 and 11 to 12°C, p < 0.10 for transfer on day 11 to 4°C) while only microgreens transferred on day 8 to 12°C showed an increase in total ACN that trended toward significance (p=0.11).

Conclusions: Microgreens transferred to 12°C on day 8 had the greatest increase in phytochemicals but also a significant reduction in yield. Transfer to 4°C on day 11 had a modest increase in phytochemicals compared to control without the loss in yield.

Funding Sources: USDA National Institute of Food and Agriculture, Hatch project COL00415, accession number 7002928