Effects of Different Light-Emitting Diode Illuminations on Bioactive Compounds in Ruby Streaks Mustard Microgreens by Ultra-High Performance Liquid Chromatography–High-Resolution Mass Spectrometry

Abstract

Mustard (Brassica juncea var. “Ruby Streaks”) is a popular microgreen species with rich phenolic and glucosinolate contents. Light-emitting diodes (LEDs) have been increasingly used to promote the content of bioactive compounds in commercially grown plants, particularly in controlled environment agriculture (CEA) settings. The present research aimed to investigate the effect of LED light wavelengths on the phytochemical profiles of the major secondary metabolites [i.e., anthocyanins, non-anthocyanin phenolics, and glucosinolates (GLs)] of Ruby Streaks mustard microgreens. Twenty-six anthocyanins, thirty-five non-anthocyanin phenolics, and six GLs were characterized in Ruby Streaks mustard extracts. Among them, three hydroxycinnamic acid-acylated Cyanidin 3-O-sophoroside-5-O-diglucosides and eight hydroxycinnamic acid-acylated flavonol-O-pentosylglucosides were newly discovered compounds in mustard microgreens. Three light treatments (blue, red, and magenta) were investigated and compared to the white (2700k) control. The red (660 nm) light and magenta (450 + 650 nm) light promoted the accumulation of both total and individual anthocyanin/aliphatic GLs, while the blue (450 nm) light was found to be the dominant factor in the accumulation of non-anthocyanin phenolics. The results suggested the significant and complex effect of lighting conditions on phytochemical accumulation in Ruby Streaks mustard microgreens, thus the potential of modulating nutritional profiles by varying wavelength of the light source.

Effect of Far-Red Light on Biomass Accumulation, Plant Morphology, and Phytonutrient Composition of Ruby Streaks Mustard at Microgreen, Baby Leaf, and Flowering Stages

“…"ruby streaks", RS) is a popular species consumed as microgreens or baby leaves, both of which are considered excellent sources for phytonutrients. 13,14 RS microgreens were found in our previous study to respond significantly to blue and red lights in terms of yield, color, morphology, and metabolomic profile. 13 Related, mature red leaf mustard (B. juncea L.) was recently found to show larger leaves and higher fresh yield with 1% FR in the spectrum compared to 11% FR.…”

“…13,14 RS microgreens were found in our previous study to respond significantly to blue and red lights in terms of yield, color, morphology, and metabolomic profile. 13 Related, mature red leaf mustard (B. juncea L.) was recently found to show larger leaves and higher fresh yield with 1% FR in the spectrum compared to 11% FR. 5 However, it remains unknown (1) whether the RS cultivar responds significantly to FR in terms of yield, morphology, and phytonutrient composition, (2) whether such responses persist or vary at different growth stages, and (3) whether RS responds differently to FR applied singularly versus FR supplemented with white light treatment.…”

Brassicaceae Microgreens: Phytochemical Compositions, Influences of Growing Practices, Postharvest Technology, Health, and Food Applications

“…In contrast, Brassica juncea species (red mustard, Dijon mustard, and wasabi microgreens) showed the lowest glucosinolates content. The most abundant glucosinolates in mustard microgreens are sinigrin, glucobrassicin, gluconapin, 4-hydroxyglucobrassicin, and 4-methoxyglucobrassicin. , Aliphatic glucosinolates are predominant compounds in broccoli microgreens. Glucoraphanin, glucoiberin, and glucoerucin are the primary glucosinolates present in broccoli microgreens. , Broccoli microgreens contain more glucoerucin and glucoraphanin glucosinolates than broccoli florets and mature broccoli leaves .…”

“…59,65 Anthocyanins are water-soluble pigments among the phenolic compounds that are not only responsible for the color of fruits and vegetables but also play a role in disease prevention. Recently, the study of Liu et al 68 reported the presence of 26 anthocyanins in mustard microgreen, of which 18 of them are acylated cyanidin (Cy)-3-O-sophoroside-5-Odiglucosides and eight are acylated Cy-3-O-sophoroside-5-Oglucosides. In another study, 30 different anthocyanins (only cyanidin derivatives) that contribute colors to red cabbage, red mustard, purple mustard, and purple kohlrabi microgreens were reported by Sun et al 65 Cyanidin-3-(feruloyl)(sinapoly)dihexoside-5-hexoside was identified by Kyriacou et al 20 as the most abundant anthocyanin component in mibuna, pak choi, mizuna, and komatsuna microgreens.…”

“…The most abundant glucosinolates in mustard microgreens are sinigrin, glucobrassicin, gluconapin, 4hydroxyglucobrassicin, and 4-methoxyglucobrassicin. 68,75 Aliphatic glucosinolates are predominant compounds in broccoli microgreens. Glucoraphanin, glucoiberin, and glucoerucin are the primary glucosinolates present in broccoli microgreens.…”