Differential Effects of Low Light Intensity on Broccoli Microgreens Growth and Phytochemicals

Abstract

To produce high-quality broccoli microgreens, suitable light intensity for growth and phytochemical contents of broccoli microgreens in an artificial light plant factory were studied. Broccoli microgreens were irradiated under different photosynthetic photon flux density (PPFD): 30, 50, 70 and 90 μmol·m−2·s−1 with red: green: blue = 1:1:1 light-emitting diodes (LEDs). The broccoli microgreens grown under 50 μmol·m−2·s−1 had the highest fresh weight, dry weight, and moisture content, while the phytochemical contents were the lowest. With increasing light intensity, the chlorophyll content increased, whereas the carotenoid content decreased. The contents of soluble protein, soluble sugar, free amino acid, flavonoid, vitamin C, and glucosinolates except for progoitrin in broccoli microgreens were higher under 70 μmol·m−2·s−1. Overall, 50 μmol·m−2·s−1 was the optimal light intensity for enhancement of growth of broccoli microgreens, while 70 μmol·m−2·s−1 was more feasible for improving the phytochemicals of broccoli microgreens in an artificial light plant factory.

Contrary to Red, Blue Monochromatic Light Improves the Bioactive Compound Content in Broccoli Sprouts

“…Following seed germination, edible sprouts are typically harvested before the development of true leaves [1,2]. In this perspective, they are immature seedlings composed of two cotyledons, hypocotyl and radicle.…”

“…In this perspective, they are immature seedlings composed of two cotyledons, hypocotyl and radicle. Sprouts typically exhibit nutritional superiority as compared to seeds, and enhanced bioactive compound content as compared to their mature counterparts [2][3][4]. In recent years, their consumption has been steadily increasing in the context of rising consumer awareness for healthy diet benefits [2,5].…”

“…Sprouts typically exhibit nutritional superiority as compared to seeds, and enhanced bioactive compound content as compared to their mature counterparts [2][3][4]. In recent years, their consumption has been steadily increasing in the context of rising consumer awareness for healthy diet benefits [2,5]. A typical example is broccoli (Brassica oleracea L.) sprouts, which are recognized as a functional food, owing to their preventive action against several chronic diseases [4,6].…”

“…Broccoli sprouts are an excellent source of a wide range of bioactive compounds including glucosinolates, anthocyanins, polyphenols, flavonoids, and vitamins, especially ascorbic acid (vitamin C) [2,6]. Glucosinolates are well-documented health promoters, with glucoraphanin being the most abundant one (>50%) in broccoli [7].…”

“…Sprout characteristics are set by the growth environment, with light and temperature arguably being the two most important conditions. While sprouts are generally cultivated in darkness [10], it was found that light exerts a promotive effect on nutritional and bioactive compound profiles depending on its quality (spectral distribution) [1,2,4]. For instance, blue (B) light exerted a promotive effect on the content of some bioactive compounds in kale [11] and broccoli [12] sprouts, and in this way has been suggested as a suitable growth spectrum [13,14].…”