Effects of preharvest lighting conditions on phenolic compounds and colour of radish microgreens: Cultivar-specific responses

Abstract

This study examined how lighting conditions (White, or a combination of Red + Blue LEDs; and supplemental UV-C: 0, 1 or 3 applications) and cultivars (Daikon, Red Rambo) affected the colour, total phenolics content, antioxidant activity and individual polyphenols of radish microgreens (Raphanus sativus L.) in a sustainable vertical farming system, as well as the implications for polyphenolic intake, connecting agronomic practices with consumption. Light treatments preserved the visual appearance of all cultivars (Delta E < 4.4), maintaining market acceptance. Individual compounds varied slightly between cultivars, along with their responses the different lighting conditions. Considering 100 g fresh microgreens, Red Rambo provided higher levels of polyphenols (155-188 mg 100 g(- 1)) than Daikon (113-127 mg 100 g(- 1)), as well as higher antioxidant activity and total phenolics content, irrespective of growing light conditions. The choice of LED light during cultivation also significantly impacted polyphenolic levels: generally, White LEDs, optimized with 1 application of UV-C, favoured phenolic production in Daikon, while Red + Blue LEDs were more effective for Red Rambo regardless of UV-C. Sinapoyl malate was the most abundant compound in both cultivars. Red Rambo also provide complex anthocyanins, whose levels (69-80 mg 100 g- 1 total anthocyanins) are enhanced by Red + Blue LEDs, making this cultivar grown under this LED combination a particularly appealing option with greater potential health benefits. These findings highlight the value of microgreens amid growing consumer interest, as sustainable, visually appealing, and bioactive compound-rich foods that support daily vegetable intake.