Brassica Microgreens Research Articles

Brassica Microgreens as Novel Sources of Cardiovascular bio-compounds: insights into hypertension management via metabolomics

Hypertension remains a prevalent global health issue, with numerous strategies aimed at mitigating its widespread impact. Recently, there has been growing interest in developing nutraceuticals derived from natural bioactive compounds with cardio-protective properties. Brassica microgreens—young, edible seedlings—are rich sources of phytochemicals, such as glucosinolates, which modulate the biological processes influencing CVDs. However, the underlying pathogenesis pathways are not yet fully understood. This study aims to investigate the effects of phytochemicals from brassica microgreens (MG) on both hypertension modulation and metabolic pathways. To achieve this, a dietary intervention using brassica microgreens was conducted on spontaneously hypertensive rats (SHR) and normotensive ones (WKY). The treatment involved a diet with 5% w/w of lyophilized brassica MG incorporated into the standard food (ad-libitum) of the animals, for either 24 h (acute treatment) or 4 weeks (chronic treatment). Systolic blood pressure and different oxidative/inflammatory markers were evaluated at the beginning and end of the treatment. Urine and plasma samples were collected post-treatment and analyzed using untargeted metabolomic approaches based on UPLC-ESI-QTOF-MS to identify the metabolic pathways alterations induced by MG intake. Chronic treatment positively influenced hemodynamic parameters, which correlated with improvements in oxidative-inflammatory marker values. Metabolomics analysis provided a robust molecular characterization of normotensive, hypertensive, treated, and untreated groups with MG. Potential metabolites associated with brassica consumption, particularly cauliflower, were identified, such as sinigrin-derived and indolic metabolites, which may be linked to hypertension modulation. This study also highlighted the impact of lipid metabolism on the hypertensive phenotype, offering new insights into the physio-pathological metabolic pathways. From this, metabolomics shows potential to emerge as a novel tool for theragnosis in arterial hypertension. Moreover, the consumption of brassica microgreens may be a valuable addition to a healthy lifestyle, potentially offering a dietary strategy for cardiovascular risk prevention and management.

Hormetic effect of UV-C radiation on red mustard microgreens growth and chemical composition

Brassica microgreens are rich in phytochemicals and are attractive crops for controlled vertical farming systems where the light spectrum can be precisely manipulated. Understanding the effects of pre-harvest hormetic UV-C light doses on plant composition and growth parameters represents a novel and largely unexplored area for precision agriculture and nutrition. Therefore, the objective of this work was to investigate the impact of exposing red mustard microgreens to low/hormetic doses of UV-C radiation on their growth, chemical composition and colour. Plants were grown in a controlled environment and exposed to 0.3 kJ m−2, 254 nm UV-C radiation at the end of the cultivation period. Treatments included a single pulse on day 7, or three pulses at days 7, 8, and 9 and harvest on day 10. UV-C radiation presented a hormetic effect, while 1 pulse of UV-C stimulated growth and productivity without significant colour changes in microgreens, 3 pulses of UV-C radiation to did not show significant effects when compared to controls (no UV-C exposure). Moreover, strong negative correlations were observed between growth parameters and chemical composition (p < 0.05). Microgreens with enhanced growth parameters showed a decrease in phenolic compounds content and antioxidant activity. Interestingly, regardless of quantification, untargeted metabolomics using UHPLC-Q-Orbitrap-MS/MS revealed that the secondary metabolites profile remained similar between control and microgreens treated with UV-C radiation.

Optimal Brassicaceae family microgreens from a phytochemical and sensory perspective

Microgreens, also called superfoods, emerge because of their high levels of nutrients, diverse flavour profiles, and sustainable cultivation methods, which make them culinary delights and valuable to a healthy and flavorful diet. The present study investigated Brassicaceae family microgreens, proposing a novel system (quality indices) that allows scoring among them. Fourteen Brassica microgreen species were morphological, phytochemical, and sensorial investigated. The morphological assessment revealed that radish microgreens exhibited the highest leaf area (p < 0.05), while red mizuna demonstrated superior yield. Cauliflower microgreens contained the highest concentrations of ascorbic acid (HPLC-DAD) and total phenolic content (p < 0.05). Phytochemical analysis using HPLC-MS/MS identified over 18 glucosinolates and phenolic compounds. Red mustard and red cabbage showed the highest glucosinolate content (p < 0.05). Watercress exhibited the highest phenolic compound content (p < 0.05), primarily flavonoids, while broccoli and radish contained the highest isothiocyanate levels. Cauliflower microgreens resulted in the most consumer-accepted variety. Appling quality indices scoring system identified radish, cauliflower, and broccoli microgreens as the most promising species. This study underscores the potential of Brassica microgreens as an excellent source of health-promoting phytochemicals with favorable market acceptance, providing valuable insights for both nutritional research and commercial applications.

First global report of Hyaloperonospora brassicae in commercial broccoli and cabbage microgreens.

Microgreens are a nutrient-dense enhancement to modern diets (Choe et al. 2018), whose small production footprint in protected systems facilitates rapid crop turnover and distribution to population centers. Eleven of the 25 most broadly grown microgreens are brassicas (Choe et al. 2018). In November 2023, kale, broccoli (H009B), and cabbage (H009C) microgreen crops in Michigan were observed with downy mildew, at disease severities of 3%, 40%, and 20% foliage on 10 x 16 cm seeded blocks of plants, respectively. These crops shared a germination chamber for at least three days, which was maintained at approximately 22℃ in very humid, dark conditions. Chlorosis and grayish, sunken necrosis characterized symptoms on cotyledon surfaces (Fig. 1). In humid conditions, thick, white-light gray sporulation was present on adaxial cotyledon surfaces, accompanied by sparse sporulation on abaxial surfaces and hypocotyls. Severely diseased plants were stunted and approximately 50% gradually succumbed to downy mildew. On microscopic examination, a Hyaloperonospora spp. was tentatively identified, with long sporangiophores that dichotomously branched 3 to 6 times and hyaline sporangia borne singly on flexuous terminal sterigmata (Fig. 2). Sporangia were round to oval, with average length of 23.1 (range 16.0 to 28.3) µm; width of 20.0 (15.0 to 25.6) µm; and average length:width of 1.2 (1.0 to 1.4); (n = 97 for all). Sporangia dislodged rapidly if disturbed or as humidity decreased. Two pathogenicity tests were initiated on two sequential days. Two cotyledons from originally infected broccoli and cabbage were suspended, abaxial-side down, on coarse mesh over an open 60-mm plate of pregerminated brassica seeds on a water-saturated filter, inside a sealed, clear plastic box. Boxes contained only one type of originally diseased host, with 15 to 20 seeds of transfer varieties in unique dishes. Boxes were incubated in the dark for 2 days at 19°C with a wet paper towel atop the cotyledons. Before removal, cotyledons were lightly brushed across the surfaces of the seedlings they were just suspended above. Seedlings were grown in boxes in the presence of indirect, ambient light for 9.5 hr/day for an additional 5 days before pathogen sporulation was apparent. Filter paper was resaturated as needed. Noninoculated control plants, maintained separate from inoculated plants, were asymptomatic throughout the experiments. Total disease incidence in transfer varieties was 43.5% of 'Graffiti' cauliflower, 18.7% and 15.7% of 'Nixon' and 'Blue Vantage' cabbage; 11.8% of 'Red Russian' kale, and 6.0% of 'Ironman' broccoli, combined from two experiments. All varieties listed had at least one plant successfully infected in both pathogenicity tests. Sporulation on transfer hosts was morphologically identical to originally affected crops. Sporangiophores and sporangia were removed from H009B broccoli and H009C cabbage plants using surface sterilized forceps, placed directly into DNA extraction tubes containing buffer CD1 (Qiagen PowerSoil Pro), then kit instructions were followed. Extracts were utilized as template for ITS and cox1 PCR amplification, using DreamTaq Mastermix and ITS4/6 (45 cycles; White et al. 1990) and Levup/Levlo primers (30 cycles; Robideau et al. 2011). Cycling conditions were as published, with the number of cycles indicated by primer set. Each reaction yielded a single amplicon of approximately 1000 and 700 bp, for ITS and cox1, respectively,. Amplicons were cleaned using ExoSap-IT and submitted for Sanger sequencing, using ITS6 and Levup as sequencing primers (Robideau et al. 2011; White et al. 1990). After quality trimming, amplicons shared >98.5% identity with H. brassicae (NCBI Genbank accession MG757792 or reference genome CANTFL010000892.1). Sequences were submitted to Genbank (PP093830, PP093831, PP776812, PP776813). This is the first report of downy mildew, caused by H. brassicae, in commercial brassica microgreens, crops with vast nutritional value and expanding production.

Brassica microgreens cabbage (Brassica oleracea), radish (Raphanus sativus) and rocket (Eruca vesicaria) (L.) Cav: application of red‐light emitting diodes lighting during postharvest storage and in vitro digestion on bioactive compounds and antioxidant activity

SummaryMicrogreens grow best under light‐emitting diodes (LED), an artificial light source. In this study, LED lights (red, blue and far‐red) were tested on brassica microgreens to see if they induced an increase in bioactive compounds (glucosinolates and phenolics). In vitro digestion also measured bioavailable bioactive compounds in the intestinal phase. LED lights (red, blue and far‐red) were applied for 6 h in storage at 5 °C and 85% RH for 5 days on cabbage (Brassica oleracea), radish (Raphanus sativus) and rocket (Eruca vesicaria (L.) Cav). Red light significantly enhanced ascorbic acid, total phenols, kaempferol and quercetin glycoside concentrations in all three Brassica microgreens and antioxidant activities. Exposure to red LED light increased 4‐methoxyglucobrassicin (cabbage), glucoraphenin (radish), glucoraphanin A and glucoerucin (rocket). Red light stress may have resulted in secondary metabolite production in immature plants. An in vitro digestion showed higher concentrations of phenolic compounds, glucosinolate components and antioxidants in the intestinal phase. Red LED light is recommended as a postharvest treatment for improving cabbage, rocket and radish bioactive compounds.

The Phytonutrient Content and Yield of Brassica Microgreens Grown in Soilless Media with Different Seed Densities

Microgreens are increasingly valued by consumers for their phytonutritional benefits. There is limited information to growers on the influence of growth media and seed density on antioxidant properties of Brassica microgreens. Therefore, the study was conducted to determine the effect of seedling media (Hygromix, Promix, and TS1) and seed density (4, 8, and 12 seeds per seed cavity) on morphological parameters, yield, color, antioxidant components, and their activities in radish (Raphanus sativus), cabbage (Brassica oleracea), and rocket (Eruca sativa) microgreens. Fourteen days after seeding, Promix at a seed density of 12 per cavity improved yield of radish, cabbage, and rocket microgreens. Irrespective of the seed density, all three Brassica microgreens grown in TS1 had higher leaf nitrogen, phosphorus, and calcium content. Interaction effects of Hygromix x seed densities were more pronounced on the antioxidant properties (DPPH and FRAP). These differences could be due to the physical properties of growth medium. Vitamin C and total glucosinolate were improved on Brassica microgreens grown in Hygromix at a seed density of 4 per cavity. Twelve seeds per cavity in Promix growth medium improved Brassica microgreens yield, whereas phytochemicals were most likely improved by growing media, Hygromix followed by TS1 and mineral content improved in TS1 followed by Hygromix at low seed density of 4 per cavity.

Light Quality Potentiates the Antioxidant Properties of Brassica rapa Microgreen Extracts against Oxidative Stress and DNA Damage in Human Cells.

Plants are an inexhaustible source of bioactive compounds beneficial for contrasting oxidative stress, leading to many degenerative pathologies. Brassica rapa L. subsp. rapa is well known for its nutraceutical properties among edible vegetable species. In our work, we aimed to explore an eco-friendly way to enhance the beneficial dietary phytochemicals in this vast world of crop-growing plants at selected light quality conditions. White broad-spectrum (W) and red-blue (RB) light regimes were used for growing brassica microgreens. The organic extracts were tested on keratinocytes upon oxidative stress to explore their capability to act as natural antioxidant cell protectors. Our results show that both W and RB extracts caused a notable reduction in reactive oxygen species (ROS) levels induced by H2O2. Interestingly, according to its higher contents of polyphenols and flavonoids, the RB was more efficient in reducing ROS amount and DNA damage than the W extract, particularly at the lowest concentration tested. However, at higher concentrations (up to 100 μg/mL), the antioxidant effect reached a plateau, and there was little added benefit. These findings confirm that RB light effectively increases the antioxidant compounds in Brassica rapa L. microgreens, thus contributing to their enhanced activity against oxidative-induced genotoxicity compared to microgreens grown under W light.

Improved metabolomic approach for evaluation of phytochemicals in mustard, kale, and broccoli microgreens under different controlled environment agriculture conditions

The fast-growing field of controlled environment agriculture (CEA) offers unprecedented opportunities for targeted improvement in concentrations of bioactive compounds in fresh produce achieved through precise modulation of production conditions. To gain full sight of the phytochemical profiles of vegetables grown under different conditions, a rapid analytical strategy is needed for the evaluation of different CEA growing conditions. In this study, Brassica microgreens including ruby streaks mustard (B. juncea), red kale (B. oleracea), and broccoli (B. oleracea) were used as model plants for the evaluation of CEA conditions. Analysis of two first leaves (cotyledons) in microgreens with minimum sample extraction and ultra-high performance liquid chromatography-high-resolution mass spectrometry (UHPLC-HRMS) based metabolomic approach was applied for phytochemical analysis for evaluation of the brassica microgreens grown under four different light sources, namely white (W), dark (D), white and far-red (WF) and far-red (F) and fertilizer conditions (CaCl2 and K2SO4). An image-based normalization method using leaf area coupled with chemometrics-based strategies including principal component analysis (PCA) and partial least squares-discriminant analysis (PLS-DA) was performed for the post-acquisition data analysis. The method successfully distinguished between Brassica microgreens grown under different CEA settings in a shortened cycle with less organic solvent and labor, which is more environmentally friendly and sustainable. Marker compounds that are responsible for differentiating the Brassica microgreens under various CEA conditions were tentatively identified. Among the tentatively identified marker compounds, gingerglycolipid A was first reported in red kale and broccoli. The results from the present study may serve as a scientific foundation for the rapid and simple assessment to optimize CEA conditions.

Membrane permeabilizers enhance biofortification of Brassica microgreens by interspecific transfer of metabolites from tea (Camellia sinensis)

Interspecific metabolite transfer (ISMT) is a novel approach for plants biofortification. In this study, the effect of tea (Camellia sinensis; Cs), with or without membrane permeabilizers EDTA and Tween, as a donor plant on broccoli, cauliflower and kale sprouts was investigated. As a result, caffeine- and catechin-enriched broccoli, cauliflower and kale microgreens were produced. Kale sprouts were most permeable for catechins from Cs, while cauliflower was most permeable for caffeine. Cs + EDTA significantly increased vitamin C in broccoli and kale. Among the tested enzymes activity, pancreatic lipase was the most affected by the treatment with broccoli and cauliflower biofortified with Cs or Cs combined with permeabilizers. Broccoli sprouts biofortified with Cs most significantly inhibited α-amylase, while those biofortified with Cs combined with permeabilizers most significantly inhibited α-glucosidase. Results point to ISMT combined with membrane permeabilizers as a promising and eco-friendly biofortification strategy to improve the biopotential of Brassica microgreens.

All Ion Fragmentation Analysis Enhances the Untargeted Profiling of Glucosinolates in Brassica Microgreens by Liquid Chromatography and High-Resolution Mass Spectrometry.

An analytical approach based on reversed-phase liquid chromatography coupled to electrospray ionization Fourier-transform mass spectrometry in negative ion mode (RPLC-ESI-(-)-FTMS) was developed for the untargeted characterization of glucosinolates (GSL) in the polar extracts of four Brassica microgreen crops, namely, garden cress, rapeseed, kale, and broccoli raab. Specifically, the all ion fragmentation (AIF) operation mode enabled by a quadrupole-Orbitrap mass spectrometer, i.e., the systematic fragmentation of all ions generated in the electrospray source, followed by the acquisition of an FTMS spectrum, was exploited. First, the best qualifying product ions for GSL were recognized from higher-energy collisional dissociation (HCD)-FTMS2 spectra of representative standard GSL. Extracted ion chromatograms (EIC) were subsequently obtained for those ions from RPLC-ESI(-)-AIF-FTMS data referred to microgreen extracts, by plotting the intensity of their signals as a function of retention time. The alignment of peaks detected in the EIC traces was finally exploited for the recognition of peaks potentially related to GSL, with the EIC obtained for the sulfate radical anion [SO4]•- (exact m/z 95.9523) providing the highest selectivity. Each putative GSL was subsequently characterized by HCD-FTMS2 analyses and by collisionally induced dissociation (CID) multistage MSn (n = 2, 3) acquisitions based on a linear ion trap mass spectrometer. As a result, up to 27 different GSLs were identified in the four Brassica microgreens. The general method described in this work appears as a promising approach for the study of GSL, known and novel, in plant extracts.

Effect of LED lights on the growth, nutritional quality and glucosinolate content of broccoli, cabbage and radish microgreens

In this study, the effects of red (R), blue (B) and far-red (FR) LED lights and their combination (R + B, R + FR, B + FR, R + B + FR) together with white (W) LED light as control, on the growth, nutritional quality and the glucosinolates of brassica microgreens were determined. Fresh and dry weights were increased with W, R, R + FR lights in broccoli and cabbage and with the R + B + FR and B + FR in radish microgreens. Soluble solids content (SSC) (%) was highest with W, R and B lights in broccoli and cabbage. The highest titratable acidity (TA) (%) was determined with B, FR, R + FR, B + FR in broccoli and W, R + FR, R + B in cabbage. In radish, lower TA was determined. In broccoli microgreens, glucoraphanin content and total GSLs were increased with B light whereas in cabbage, the combination of R + B revealed the highest aliphatics, In radish, glucoraphenin was highest in B light and the glucoraphasatin in R, FR, R + FR and B lights.

Selection of suitable growing substrates and quality assessment of Brassica microgreens cultivated in greenhouse

Brassica microgreens are typically cultivated using a peat-based growing substrate with a higher production cost as this substrate must be imported from overseas. In Vietnam, a source of local bio-materials that could be used to replace imported peat, resulting in more affordable growing substrates. Several growing substrates for Brassica microgreens were evaluated in this study: GT1 (30% sand +20% organic soil + 50% coco coir), GT2 (75% coco coir + 25% rice husk), GT3 (75% coco coir + CaO 2.2 mg/kg + acid humic 0.41%) and imported peat GT4 (75% white sphagnum peat +25% vermiculite (size 4–6 mm). The local organic material coco coir GT3 was found to be as effective as the imported substrate for microgreen production. The material coco coir mixed with soil and sand could increase the risks of soil-borne disease infestation on Brassica microgreens. Microgreens grown in the substrate GT3 and GT4 had higher productivity and lower disease infestation levels than other tested substrates. Nitrate level and microbiological contamination (E. coli and Salmonella spp.) of Brassica microgreens cultivated in these substrates were determined to be at safe levels.

Light Intensity and Photoperiod Affect Growth and Nutritional Quality of Brassica Microgreens.

We explored the effects of different light intensities and photoperiods on the growth, nutritional quality and antioxidant properties of two Brassicaceae microgreens (cabbage Brassica oleracea L. and Chinese kale Brassica alboglabra Bailey). There were two experiments: (1) four photosynthetic photon flux densities (PPFD) of 30, 50, 70 or 90 μmoL·m−2·s−1 with red:blue:green = 1:1:1 light-emitting diodes (LEDs); (2) five photoperiods of 12, 14, 16, 18 or 20 h·d−1. With the increase of light intensity, the hypocotyl length of cabbage and Chinese kale microgreens shortened. PPFD of 90 μmol·m−2·s−1 was beneficial to improve the nutritional quality of cabbage microgreens, which had higher contents of chlorophyll, carotenoids, soluble sugar, soluble protein and vitamin C, as well as increased antioxidant capacity. The optimal PPFD for Chinese kale microgreens was 70 μmol·m−2·s−1. Increasing light intensity could increase the antioxidant capacity of cabbage and Chinese kale microgreens, while not significantly affecting glucosinolate (GS) content. The dry and fresh weight of cabbage and Chinese kale microgreens were maximized with a 14-h·d−1 photoperiod. The chlorophyll, carotenoid and soluble protein content in cabbage and Chinese kale microgreens were highest for a 16-h·d−1 photoperiod. The lowest total GS content was found in cabbage microgreens under a 12-h·d−1 photoperiod and in Chinese kale microgreens under 16-h·d−1 photoperiod. In conclusion, the photoperiod of 14~16 h·d−1, and 90 μmol·m−2·s−1 and 70 μmol·m−2·s−1 PPFD for cabbage and Chinese kale microgreens, respectively, were optimal for cultivation.

Effect of combined light-emitting diodes on the accumulation of glucosinolates in Brassica microgreens

As of recent, microgreen vegetable production in controlled environments are being investigated for their bioactive properties. Phytochemicals like glucosinolates (GLS) are highly sensitive to varying spectral qualities of light, especially in leafy greens of Brassica where the responses are highly species-dependent. The accumulation of bioactive GLS were studied under 8 different treatments of combined amber (590 nm), blue (455 nm), and red (655 nm) light-emitting diodes (rbaLED). A semi-targeted metabolomics approach was carried out to profile common intact-GLS in microgreen extracts of Brassica by means of LC-HRMS/MS. Thirteen GLS were identified, among them were 8 aliphatic, 4 indolic and 1 aromatic GLS. Mass spectrometry data showed sinigrin had the highest average concentration and was highest in B. juncea, progoitrin was highest in B. rapa and glucobrassicin in R. sativus. The individual and total GLS in the microgreens of the present study were largely different under rbaLED; B. rapa microgreens contained the highest profile of total GLS, followed by R. sativus and B. juncea. Sinigrin was increased and gluconasturtiin was decreased under rbaLED lighting in most microgreens, glucoalyssin uniquely increased in R. sativus and decreased in B. rapa and glucobrassicin uniquely decreased in both B. rapa and B. juncea. The present study showed that rbaLED contributed to the altered profiles of GLS resulting in their significant modulation. Optimizing the light spectrum for improved GLS biosynthesis could lead to production of microgreens with targeted health-promoting properties.Graphical

Characterization and profiling of polyphenolics of Brassica microgreens by LC-HRMS/MS and the effect under LED light

An untargeted approach to profiling of polyphenolics of Brassicaceae microgreens was employed to characterize the phenolic composition in microgreens grown under 8 different treatments of combined amber (590 nm), blue (455 nm), and red (655 nm) LED, using full MS and HRMS/MS-ESI. Hydroxycinnamic acid (HCA) derivatives predominated the pool of phenolics in the microgreens, followed by free phenolic acids and flavonol glycosides/acylglycosides, with most of the HCA derivatives existing as malate esters. Most HCA malates in mustard (Barbarossa) and all HCA malates in mizuna (red kingdom)/ radish (red Rambo, organic) were significantly decreased under most treatments, whereas all malates were overall increased under combined lighting in radish (red Rambo), mustard (Garnet Giant), mizuna (organic), Pac choi (red Pac) and mustard (Scarlet Frills). The present study demonstrated that amber in combination with blue and red LED contributed to the altered phenolic profile and increase and/or decrease in quantity of certain phenolic compounds, particularly the HCA malates.

Posidonia Natural Residues as Growing Substrate Component: An Ecofriendly Method to Improve Nutritional Profile of Brassica Microgreens.

The aim of this study was to test Posidonia oceanica (L.) Delile seagrass residues (leaves and fibers) as growing media component to improve the nutritional quality of two different brassica microgreens (Mizuna and Rapini). We hypothesized that addition of posidonia residues in the substrate would result in higher concentration of certain mineral nutrients in the edible parts of plants. Substrates were obtained by mixing leaves and fibers, each material at the rate of 25, 50 and 75% (v/v), with a peat based commercial substrate, that was also used at 100% rate as a control treatment. Two experiments were carried out (Experiment 1: Mizuna microgreens production in growth chamber conditions; Experiment 2: Mizuna and Rapini microgreens production in greenhouse conditions). Plant growth measurements and chemical analysis on edible parts (mineral tissue composition and main bioactive compounds - polyphenol, chlorophylls and carotenoids contents) were performed in order to evaluate the effects of the different substrates on growth and nutritional composition of brassica microgreens. In order to evaluate the consumer safety, daily intake, percentage of recommended daily allowance for I (RDA-I) and hazard quotient (HQ) for I intake through consumption of 50 and 100 g portions of Rapini microgreens were calculated. Posidonia in the growing media mixtures increased I and B content in edible parts of microgreens. The calculated HQ underlines the safety of these products. Results confirm the possibility to improve nutritional profile of brassica microgreens by using this natural material as a growing media component, resulting in a sustainable approach.

LED-Induced Carotenoid Synthesis and Related Gene Expression in Brassica Microgreens

In this study, various ratios of combined red, blue, and amber light-emitting diodes (rbaLEDs) were investigated for their effect on the expression of carotenoid biosynthetic genes and carotenoid accumulation in eight Brassica microgreens. Total and individual (β-carotene, lutein, α-carotene, neoxanthin, and violaxanthin) carotenoids were increased 20-44 and 10-55%, respectively, under dose-dependent increasing amber-blue light and decreasing red in most microgreens. Lipophilic 2,2-diphenyl-1-picrylhydrazyl and ferric reducing antioxidant power antioxidant activities were significantly increased under higher amber and blue light fractions, while oxygen radical absorbance capacity was generally decreased. Under rbaLED in mizuna (B. rapa) microgreens, the lycopene epsilon cyclase (LYCε) expression was 10-15-fold higher, which resulted in downstream accumulation of α-carotene and lutein. Lycopene beta cyclase (LYCβ) was not significantly changed, suggesting that β-carotene, violaxanthin and neoxanthin were mainly controlled by upstream phytoene synthase and branch-point LYCε. Increased beta-ring carotenoid hydroxylase (CHXβ) expression was also consistent with lutein accumulation. This study demonstrated for the first time that amber LED was involved in the regulatory mechanism of carotenoid biosynthesis, thus a potential novel approach to production of antioxidant-rich microgreens.

The Use of a Nutrient Quality Score is Effective to Assess the Overall Nutritional Value of Three Brassica Microgreens.

Microgreens have immense potential for improving dietary patterns, but little information is available regarding their overall nutritional value. We evaluated the nutritional traits of three hydroponically grown Brassica microgreens by using a Nutrient Quality Score. Micro cauliflower, micro broccoli and micro broccoli raab were grown using nutrient solutions with three different NH4:NO3 molar ratios (5:95, 15:85, and 25:75). Protein, dietary fiber, β-carotene, α-tocopherol and mineral elements (Ca, K, Mg, Fe, Zn, Cu, Mn, and Na) were analyzed. We developed the Nutrient Quality Score (NQS 11.1) on the basis of 11 desirable nutrients and 1 nutrient (sodium) to be limited. All Brassica microgreens are an excellent source of Vitamins A and E (more than 20% of the daily reference value—DRV), as well as a good source of calcium and manganese (10–19% of the DRV). Micro cauliflower showed a NQS 11.1 at 47% higher than micro broccoli raab and micro broccoli. Using NH4:NO3 25:75 molar ratio, the average score was 27% higher than other molar ratios. In all cases, the microgreens in the present study showed a higher NQS 11.1 than their mature counterpart (on the basis of data from the United States Department of Agriculture), highlighting that the score of micro cauliflower was about six-fold higher than mature cauliflower. In conclusion, the NQS 11.1 was useful for assessing the overall nutritional quality of the three Brassica microgreens, instead of simply quantifying nutrient content, in order to compare a single nutrient among different genotypes. Furthermore, the results highlight that the micro broccoli raab, micro broccoli and micro cauliflower in this study can be considered nutrient-rich vegetables that are able to improve dietary patterns more effectively than their mature counterparts.

Yield and Quality Characteristics of Brassica Microgreens as Affected by the NH4:NO3 Molar Ratio and Strength of the Nutrient Solution.

Microgreens are gaining more and more interest, but little information is available on the effects of the chemical composition of the nutrient solution on the microgreen yield. In this study, three Brassica genotypes (B. oleracea var. italica, B. oleracea var. botrytis, and Brassica rapa L. subsp. sylvestris L. Janch. var. esculenta Hort) were fertigated with three modified strength Hoagland nutrient solutions (1/2, 1/4, and 1/8 strength) or with three modified half-strength Hoagland nutrient solutions with three different NH4:NO3 molar ratios (5:95, 15:85, and 25:75). Microgreen yields and content of inorganic ions, dietary fiber, proteins, α-tocopherol, and β-carotene were evaluated. Micro cauliflower showed the highest yield, as well as a higher content of mineral elements and α-tocopherol (10.4 mg 100 g−1 fresh weight (FW)) than other genotypes. The use of nutrient solution at half strength gave both a high yield (0.23 g cm−2) and a desirable seedling height. By changing the NH4:NO3 molar ratio in the nutrient solution, no differences were found on yield and growing parameters, although the highest β-carotene content (6.3 mg 100 g−1 FW) was found by using a NH4:NO3 molar ratio of 25:75. The lowest nitrate content (on average 6.8 g 100 g−1 dry weight) was found in micro broccoli and micro broccoli raab by using a nutrient solution with NH4:NO3 molar ratios of 25:75 and 5:95, respectively. Micro cauliflower fertigated with a NH4:NO3 molar ratio of 25:75 showed the highest dry matter (9.8 g 100 g−1 FW) and protein content (4.2 g 100 g−1 FW).

Evaluation of growth and nutritional value of Brassica microgreens grown under red, blue and green LEDs combinations.

Microgreens are rich functional crops with valuable nutritional elements that have health benefits when used as food supplements. Growth characterization, nutritional composition profile of 21 varieties representing five species of the Brassica genus as microgreens were assessed under light-emitting diodes (LEDs) conditions. Microgreens were grown under four different LEDs ratios (%); red:blue 80:20 and 20:80 (R80 :B20 and R20 :B80 ), or red:green:blue 70:10:20 and 20:10:70 (R70 :G10 :B20 and R20 :G10 :B70 ). Results indicated that supplemental lighting with green LEDs (R70 :G10 :B20 ) enhanced vegetative growth and morphology, while blue LEDs (R20 :B80 ) increased the mineral and vitamin contents. Interestingly, by linking the nutritional content with the growth yield to define the optimal LEDs setup, we found that the best lighting to promote the microgreen growth was the green LEDs combination (R70 :G10 :B20 ). Remarkably, under the green LEDs combination (R70 :G10 :B20 ) conditions, the microgreens of Kohlrabi purple, Cabbage red, Broccoli, Kale Tucsan, Komatsuna red, Tatsoi and Cabbage green, which can benefit human health in conditions with limited food, had the highest growth and nutritional content.