Comparison between the mineral profile and nitrate content of microgreens and mature lettuces

Emergence of microgreens as a valuable food, current understanding of their market and consumer perception: A review

Green leafy vegetables, especially microgreens are gaining popularity due to their high nutritional profiles, rich phytochemical content, and intense flavors. This review explores the growing commercial market for microgreens, especially in upscale dining and premium grocery outlets, highlighting consumer perceptions and their effect on market dynamics. Apart from these, the effect of modern agricultural methods that maximize the growth of microgreens is also examined. The value is anticipated to increase significantly, according to market predictions, from $1.7 billion in 2022 to $2.61 billion by 2029. Positive consumer views on microgreens health benefits drive this growth, although challenges such as varying levels of consumer awareness and income disparities affect sales. The review underscores the need for targeted research and strategic initiatives to enhance consumer understanding and improve cultivation methods to support market expansion in upcoming years.

Nitrate, Nitrite, and Iodine Concentrations in Commercial Edible Algae: An Observational Study

Edible algae are a natural source of nutrients, including iodine, and can also contain nitrogen in the form of nitrate (NO3-) and nitrite (NO2-) as they can fix nitrogen from seawater. This study aimed to analyse the NO3-, NO2-, and iodine concentrations in eighteen macroalgae and five microalgae species commercially available in the United Kingdom. NO3- and NO2- concentrations were measured using high-performance liquid chromatography (HPLC), and iodine was determined using inductively coupled plasma mass spectrometry (ICP-MS). NO3- and iodine concentrations in macroalgae (NO3-: 4050.13 ± 1925.01 mg/kg; iodine: 1925.01 ± 1455.80 mg/kg) were significantly higher than in microalgae species (NO3-: 55.73 ± 93.69 mg/kg; iodine: 17.61 ± 34.87 mg/kg; p < 0.001 for both). In the macroalgae group, nori had the highest NO3- (17,191.33 ± 980.89 mg/kg) and NO2- (3.64 ± 2.38 mg/kg) content, as well as the highest iodine content. Among microalgae, Dunaliella salina had the highest concentration of NO3- (223.00 ± 21.93 mg/kg) and iodine (79.97 ± 0.76 mg/kg), while Spirulina had the highest concentration of NO2- (7.02 ± 0.13 mg/kg). These results indicate that commercially available edible algae, particularly macroalgae species, could be a relevant dietary source of NO3- and iodine.

Plant-derived biostimulant as priming agents enhanced antioxidant and nutritive properties in brassicaceous microgreens

BACKGROUND

Microgreens constitute dietary sources of bioactive compounds imparting numerous health benefits and enhancing sensory experience. They can be successfully cultivated in soilless systems where biostimulants can be easily integrated as seed-priming and post-germination agents improving the sustainability of a crop's final production. Compared to an untreated control, three priming agents (a commercial legume-derived protein hydrolysate (A250), a novel protein hydrolysate derived from peanut biomass (H250) and hydropriming (H2O)) were applied to Komatsuna and Mibuna seeds grown as microgreens and compared for their effects on yield parameters, mineral composition, ABTS and FRAP antioxidant capacity, carotenoid concentration and phenolic compounds.

RESULTS

Significant effects of the main experimental factors and their interactions were identified on antioxidant capacity. Compared to the control and hydropriming, the highest ABTS and FRAP values were observed in Mibuna with the A250 and H250 treatments, respectively. Additionally, the H250 treatment increased the total concentrations of phenolic acid derivatives and flavonoid derivatives in Mibuna and Komatsuna, in tune with the levels of total flavonoids. Concerning mineral composition, the highest concentrations in both species were those of phosphorus and nitrate.

CONCLUSION

These results highlight the potential of select plant-based biostimulants as priming agents to enhance the antioxidant capacity, nutrient content and bioactive compound content, thus further increasing their functional and nutritive quality. In the light of this, the possibility of reducing the application of fertilizers by promoting a green transition for the intensive production of microgreens could subsequently be evaluated. © 2024 Society of Chemical Industry.

Variations in photoperiods and their impact on yield, photosynthesis and secondary metabolite production in basil microgreens

BACKGROUND

The effects of different photoperiods on plant phytochemical synthesis can be improved by adjusting the daily light integral. Photoperiod is one of the most important environmental factors that control growth, plant's internal rhythm and the synthesis of secondary metabolites. Information about the appropriate standard in terms of photoperiod for growing basil microgreens as one of the most important medicinal plants is limited. In this study, the effects of five different photoperiods, 6 (6 h × 3 cycles), 8 (8 h × 2 cycles), 16, 18, and 24 h day- 1 on the yield, photosynthesis and synthesis of secondary metabolites of three cultivars and one genotype of basil microgreens in floating system were evaluated. The purpose of this research was to determine the feasibility of using permanent light in growing basil microgreens and to create the best balance between beneficial secondary metabolites and performance.

RESULTS

The results showed that the effects of photoperiod and cultivar on all investigated traits and their interaction on photosynthetic pigments, antioxidant capacity, total phenolic compounds, proline content and net photosynthesis rate were significantly different at the 1% level. The highest levels of vitamin C, flavonoids, anthocyanins, yield and antioxidant potential composite index (APCI) were obtained under the 24-h photoperiod. The highest antioxidant capacity was obtained for the Kapoor cultivar, and the highest total phenolic compound and proline contents were measured for the Ablagh genotype under a 24-h photoperiod. The highest yield (4.36 kg m- 2) and APCI (70.44) were obtained for the Ablagh genotype. The highest nitrate content was obtained with a photoperiod of 18 h for the Kapoor cultivar. The highest net photosynthesis rate was related to the Violeto cultivar under a 24-hour photoperiod (7.89 μmol CO2 m- 2 s- 1). Antioxidant capacity and flavonoids had a positive correlation with phenolic compounds and vitamin C. Yield had a positive correlation with antioxidant capacity, flavonoids, vitamin C, APCI, and proline.

CONCLUSIONS

Under continuous light conditions, basil microgreens resistance to light stress by increasing the synthesis of secondary metabolites and the increase of these biochemical compounds made basil microgreens increase their performance along with the increase of these health-promoting compounds. The best balance between antioxidant compounds and performance was achieved in continuous red + blue light. Based on these results, the use of continuous artificial LED lighting, due to the increase in plant biochemical with antioxidant properties and yield, can be a suitable strategy for growing basil microgreens in floating systems.

Adjustments of the Phytochemical Profile of Broccoli to Low and High Growing Temperatures: Implications for the Bioactivity of Its Extracts

Climate change causes shifts in temperature patterns, and plants adapt their chemical content in order to survive. We compared the effect of low (LT) and high (HT) growing temperatures on the phytochemical content of broccoli (Brassica oleracea L. convar. botrytis (L.) Alef. var. cymosa Duch.) microgreens and the bioactivity of their extracts. Using different spectrophotometric, LC-MS/MS, GC-MS, and statistical methods, we found that LT increased the total phenolics and tannins in broccoli. The total glucosinolates were also increased by LT; however, they were decreased by HT. Soluble sugars, known osmoprotectants, were increased by both types of stress, considerably more by HT than LT, suggesting that HT causes a more intense osmotic imbalance. Both temperatures were detrimental for chlorophyll, with HT being more impactful than LT. HT increased hormone indole-3-acetic acid, implying an important role in broccoli's defense. Ferulic and sinapic acid showed a trade-off scheme: HT increased ferulic while LT increased sinapic acid. Both stresses decreased the potential of broccoli to act against H2O2 damage in mouse embryonal fibroblasts (MEF), human keratinocytes, and liver cancer cells. Among the tested cell types treated by H2O2, the most significant reduction in ROS (36.61%) was recorded in MEF cells treated with RT extracts. The potential of broccoli extracts to inhibit α-amylase increased following both temperature stresses; however, the inhibition of pancreatic lipase was increased by LT only. From the perspective of nutritional value, and based on the obtained results, we conclude that LT conditions result in more nutritious broccoli microgreens than HT.

Preharvest Methyl Jasmonate Treatment Affects the Mineral Profile, Metabolites, and Antioxidant Capacity of Radish Microgreens Produced without Substrate

This study investigated the impact of Methyl Jasmonate (MeJA) application on the nutritional content and yield of five different colored radish microgreens. Microgreens were produced without substrate and subjected to 0.5 mM and 1.0 mM MeJA treatments on the 7th day, three days before harvest. The parameters measured included yield, dry matter, minerals, amino acids, secondary metabolites such as chlorophylls (Chls), anthocyanins, flavonoids, phenolics, glucosinolates (GSLs), vitamin C, and antioxidant capacity. MeJA at 1.0 mM generally improved yield and dry weight across cultivars, and all microgreens exhibited rich mineral and amino acid composition, with the influence of cultivar being more significant than MeJA treatment. However, MeJA enhanced all cultivars' anthocyanins, GSLs, phenolics, flavonoids, and antioxidant activities. Generally, as the antioxidant capacity is the primary factor influencing the nutritional quality of microgreens, MeJA-treated microgreens, especially with selected superior cultivars such as 'Asia purple' and 'Koregon red', could offer a potential for cultivation of value-added, eco-friendly microgreens with substrate-free cultivation.

Microgreens on the rise: Expanding our horizons from farm to fork

Escalating public health concerns necessitate innovative approaches to food sources. Microgreens, nutrient-rich seedlings of vegetables and herbs, have gained recognition as functional foods. This review explores the evolution of microgreens, cultivation methods, biochemical changes during germination, nutritional content, health benefits, and commercial significance. Comprehensive studies have demonstrated that microgreens have an elevated level of various nutrients. Further, in vitro and in vivo research validated their antioxidant, anticancer, antibacterial, anti-inflammatory, anti-obesity, and antidiabetic properties. Microgreens, termed "desert food," show promise for sustainable food production in climate-vulnerable regions. This paper synthesizes recent research on microgreens, addressing challenges and gaps in understanding their nutritional content and health benefits. It contributes valuable insights for future research, fostering sustainable agriculture and enhancing understanding of microgreens in human health and nutrition.

Selenium biofortification of microgreens: Influence on phytochemicals, pigments and nutrients

Kale (Brassica oleracea L. var. sabellica L.), kohlrabi (Brassica oleracea L. var. gongylodes L.) and wheat (Triticum aestivum L. cv. Bancal) microgreens were cultivated in presence of selenium 20 μmol L-1 as sodium selenite and sodium selenate mixture. The influence of this biofortification process was evaluated in terms of biomass production, total Se, macro- and micronutrients concentration, polyphenols, antioxidant activity, chlorophylls and carotenoids levels and total soluble proteins content. The results obtained have shown a significant concentration of total Se in the biofortified microgreens of kale (133 μg Se·g-1 DW) and kohlrabi (127 μg Se·g-1 DW) higher than that obtained for wheat (28 μg Se·g-1 DW). The Se uptake in all the species did not produce oxidative damage to the plants reflected in the bioactive compounds, antioxidant capacity or pigments concentration. These Se-enriched microgreens may contribute to the recommended intake of this nutrient in human diet as to overcome Se-deficiency.

Morphological and Photosynthetic Parameters of Green and Red Kale Microgreens Cultivated under Different Light Spectra

Microgreens are plants eaten at a very early stage of development, having a very high nutritional value. Among a large group of species, those from the Brassicaceae family, including kale, are very popularly grown as microgreens. Typically, microgreens are grown under controlled conditions under light-emitting diodes (LEDs). However, the effect of light on the quality of grown microgreens varies. The present study aimed to determine the effect of artificial white light with varying proportions of red (R) and blue (B) light on the morphological and photosynthetic parameters of kale microgreens with green and red leaves. The R:B ratios were for white light (W) 0.63, for red-enhanced white light (W + R) 0.75, and for white and blue light (W + B) 0.38 at 230 µmol m-2 s-1 PPFD. The addition of both blue and red light had a positive effect on the content of active compounds in the plants, including flavonoids and carotenoids. Red light had a stronger effect on the seedling area and the dry mass and relative chlorophyll content of red-leaved kale microgreens. Blue light, in turn, had a stronger effect on green kale, including dry mass. The W + B light combination negatively affected the chlorophyll content of both cultivars although the leaves were significantly thicker compared to cultivation under W + R light. In general, the cultivar with red leaves had less sensitivity to the photosynthetic apparatus to the spectrum used. The changes in PSII were much smaller in red kale compared to green kale. Too much red light caused a deterioration in the PSII vitality index in green kale. Red and green kale require an individual spectrum with different proportions of blue and red light at different growth stages to achieve plants with a large leaf area and high nutritional value.

Comparative Analysis of Volatile Compounds from Four Radish Microgreen Cultivars Based on Ultrasonic Cell Disruption and HS-SPME/GC-MS

The ultrasonic cell disruption method was used to efficiently extract isothiocyanates and other volatile compounds from radish microgreens. A total of 51 volatiles were identified and quantified by headspace solid-phase micro-extraction and gas chromatography-mass spectrometry (HS-SPME/GC-MS) in four radish microgreen cultivars, mainly including alcohols, aldehydes, isothiocyanates, sulfides, ketones, esters, terpenes, and hydrocarbons. The correlation between cultivars and volatile compounds was determined by chemometrics analysis, including principal component analysis (PCA) and hierarchical clustering heat maps. The aroma profiles were distinguished based on the odor activity value (OAV), odor contribution rate (OCR), and radar fingerprint chart (RFC) of volatile compounds. This study not only revealed the different flavor characteristics in four cultivars but also established a theoretical basis for the genetic improvement of radish microgreen flavors.

Variation of Mineral Composition in Different Fruit Parts of Bitter Gourd (Momordica charantia L.)

Bitter gourd (Momordica charantia L.), belonging to family Cucurbitaceae, is a good source of carbohydrates, proteins, vitamins, minerals, and bioactive compounds. In the present study, fruits (and its parts-epicarp, mesocarp, endocarp, seed, and whole fruit) of 56 accessions and 4 cultivars of Momordica spp. were assayed and compared for macro-minerals magnesium (Mg), potassium (K), sodium (Na), phosphorus (P), and calcium (Ca), and microminerals iron (Fe), zinc (Zn), manganese (Mn), and copper (Cu). Potassium was the most abundant macro-mineral found in whole fruit ranging from 78.40 to 483.49 mg/100 g dry weight (DW), followed by Mg (13.23-101.70 mg/100 g DW) in epicarp, P (32.22-98.24 mg/100 g DW) in endocarp, Ca (23.41-71.39 mg/100 g DW) in whole fruit, and Na (6.09-18.56 mg/100 g DW) in epicarp. The concentration of microminerals was recorded higher in seeds compared to other fruit parts. Levels of Fe were higher (0.76-6.14 mg/100 g DW), followed by Zn (0.87-2.64 mg/100 g DW), Cu (137.68-525.45 µg/100 g DW), and Mn (46.92-179.05 µg/100 g DW). The analysis depicted bitter gourd to be a potential source of both macro-minerals (K and Mg) and microminerals (Fe and Zn). The consumption of bitter gourd could be a health-promoting strategy to meet daily dietary intake requirements of essential minerals for human health.

Comprehensive Analysis of Physicochemical, Functional, Thermal, and Morphological Properties of Microgreens from Different Botanical Sources

Due to the significant increase in global pollution and a corresponding decrease in agricultural land, there is a growing demand for sustainable modes of modern agriculture that can provide nutritious food. In this regard, microgreens are an excellent option as they are loaded with nutrients and can be grown in controlled environments using various vertical farming approaches. Microgreens are salad crops that mature within 15-20 days, and they have tender leaves with an abundant nutritive value. Therefore, this study aims to explore the physicochemical, techno-functional, functional, thermal, and morphological characteristics of four botanical varieties of microgreens, including carrot (Daucus carota), spinach (Spinacia oleracea), bathua (Chenopodium album), and Bengal gram (Cicer arietinum), which are known for their exceptional nutritional benefits. Among the four botanical varieties of microgreens studied, bathua microgreens demonstrated the highest protein content (3.40%), water holding capacity (1.58 g/g), emulsion activity (56.37%), and emulsion stability (53.72%). On the other hand, Bengal gram microgreens had the highest total phenolic content (32.2 mg GAE/g), total flavonoid content (7.57 mg QE/100 g), and DPPH activity (90.60%). Fourier transform infrared spectroscopy analysis of all microgreens revealed the presence of alkanes, amines, and alcohols. Moreover, X-ray diffraction analysis indicated low crystallinity and high amorphousness in the microgreens. Particle size analysis showed that the median, modal, and mean sizes of the microgreens ranged from 110.327 to 952.393, 331.06 to 857.773, and 97.567 to 406.037 μm, respectively. As per the observations of the results, specific types of microgreens can be utilized as an ingredient in food processing industry, including bakery, confectionery, and more, making them a promising nutritive additive for consumers. This study sheds light on various food-based analytical parameters and offers a foundation for future research to fully harness the potential of microgreens as a novel and sustainable food source, benefiting both the industry and consumers alike.

Applying productivity and phytonutrient profile criteria in modelling species selection of microgreens as Space crops for astronaut consumption

Introduction

Long-duration missions in outer Space will require technologies to regenerate environmental resources such as air and water and to produce food while recycling consumables and waste. Plants are considered the most promising biological regenerators to accomplish these functions, due to their complementary relationship with humans. Plant cultivation for Space starts with small plant growth units to produce fresh food to supplement stowed food for astronauts' onboard spacecrafts and orbital platforms. The choice of crops must be based on limiting factors such as time, energy, and volume. Consequently, small, fast-growing crops are needed to grow in microgravity and to provide astronauts with fresh food rich in functional compounds. Microgreens are functional food crops recently valued for their color and flavor enhancing properties, their rich phytonutrient content and short production cycle. Candidate species of microgreens to be harvested and eaten fresh by crew members, belong to the families Brassicaceae, Asteraceae, Chenopodiaceae, Lamiaceae, Apiaceae, Amarillydaceae, Amaranthaceae, and Cucurbitaceae.

Methods

In this study we developed and applied an algorithm to objectively compare numerous genotypes of microgreens intending to select those with the best productivity and phytonutrient profile for cultivation in Space. The selection process consisted of two subsequent phases. The first selection was based on literature data including 39 genotypes and 25 parameters related to growth, phytonutrients (e.g., tocopherol, phylloquinone, ascorbic acid, polyphenols, lutein, carotenoids, violaxanthin), and mineral elements. Parameters were implemented in a mathematical model with prioritization criteria to generate a ranking list of microgreens. The second phase was based on germination and cultivation tests specifically designed for this study and performed on the six top species resulting from the first ranking list. For the second selection, experimental data on phytonutrients were expressed as metabolite production per day per square meter.

Results and discussion

In the final ranking list radish and savoy cabbage resulted with the highest scores based on their productivity and phytonutrient profile. Overall, the algorithm with prioritization criteria allowed us to objectively compare candidate species and obtain a ranking list based on the combination of numerous parameters measured in the different species. This method can be also adapted to new species, parameters, or re-prioritizing the parameters for specific selection purposes.

Yield performance, mineral profile, and nitrate content in a selection of seventeen microgreen species

Introduction

Originally regarded as garnish greens, microgreens are increasingly valued for their nutritional profile, including their mineral content.

Methods

A study was conducted under controlled environmental conditions utilizing a selection of seventeen microgreen species belonging to seven different botanical families to investigate the genetic variation of macro- and micro-minerals and nitrate (NO3 -) content. Plants were grown in a soilless system using a natural fiber mat as the substrate. After germination, microgreens were fertigated with a modified half-strength Hoagland solution prepared using deionized water and without adding microelements. At harvest (10 to 19 days after sowing, based on the species), yield components were measured and dry tissue samples were analyzed for the concentration of total nitrogen (N), NO3 -, P, K, Ca, Mg, S, Na, Fe, Zn, Mn, Cu, and B.

Results and discussion

Genotypic variations were observed for all of the examined parameters. Nitrogen and K were the principal macronutrients accounting for 38.4% and 33.8% of the total macro-minerals concentration, respectively, followed in order by Ca, P, S, and Mg. Except for sunflower (Helianthus annuus L.), all the tested species accumulated high (1,000-2,500 mg kg-1 FW) or very high (>2,500 mg kg-1 FW) NO3 - levels. Eight of the studied species had a K concentration above 300 mg 100 g-1 FW and could be considered as a good dietary source of K. On the other hand, scallion (Allium fistulosum L.), red cabbage (Brassica oleracea L. var. capitata), amaranth (Amaranthus tricolor L.), and Genovese basil (Ocinum basilicum L.) microgreens were a good source of Ca. Among micro-minerals, the most abundant was Fe followed by Zn, Mn, B, and Cu. Sunflower, scallion, and shiso (Perilla frutescens (L.) Britton) were a good source of Cu. Moreover, sunflower was a good source of Zn, whereas none of the other species examined could be considered a good source of Fe and Zn, suggesting that supplementary fertilization may be required to biofortify microgreens with essential microminerals. In conclusion, the tested microgreens can be a good source of minerals showing a high potential to address different dietary needs; however, their yield potential and mineral profile are largely determined by the genotype.

Growth and Biochemical Composition of Microgreens Grown in Different Formulated Soilless Media

Microgreens are immature young plants grown for their health benefits. A study was performed to evaluate the different mixed growing media on growth, chemical composition, and antioxidant activities of four microgreen species: namely, kale (Brassica oleracea L. var. acephala), Swiss chard (Beta vulgaris var. cicla), arugula (Eruca vesicaria ssp. sativa), and pak choi (Brassica rapa var. chinensis). The growing media were T1.1 (30% vermicast + 30% sawdust + 10% perlite + 30% PittMoss (PM)); T2.1 (30% vermicast + 20% sawdust + 20% perlite + 30% PM); PM was replaced with mushroom compost in the respective media to form T1.2 and T2.2. Positive control (PC) was Pro-mix BX™ potting medium alone. Root length was the highest in T1.1 while the shoot length, root volume, and yield were highest in T2.2. Chlorophyll and carotenoid contents of Swiss chard grown in T1.1 was the highest, followed by T2.2 and T1.1. Pak choi and kale had the highest sugar and protein contents in T2.2, respectively. Consistently, total phenolics and flavonoids of the microgreens were increased by 1.5-fold in T1.1 and T2.2 compared to PC. Antioxidant enzyme activities were increased in all the four microgreens grown in T1.1 and T2.2. Overall, T2.2 was the most effective growing media to increase microgreens plant growth, yield, and biochemical composition.

Comparison of Mineral Composition in Microgreens and Mature leaves of Celery (Apium graveolens L.)

Celery (Apium graveolens L.), a medicinal crop, occupies a significant position in the human diet possessing several essential macro- and microelements. For proper proximate analysis, an experiment was executed by taking 20 celery genotypes. The genotypes were analyzed for macro- and microminerals which include nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), sodium (Na), sulfur (S), zinc (Zn), iron (Fe), copper (Cu), and manganese (Mn). Results from analysis revealed that the  amount of N, P, Ca, Na, and S was higher in microgreens, whereas a higher value for K was found in mature leaves. Zn, Cu, and Mn contents were found to be higher in mature leaves, while no significant difference was observed for Fe content in microgreens and mature leaves. The inclusion of celery microgreens in our daily diet would fulfill a significant portion of our daily mineral requirement. This is the first report on mineral comparison between microgreens and mature leaves of celery. It opens a new avenue for further enhancement of minerals via biofortification of this medicinal wonder crop through systematic breeding efforts. On the basis of mineral analysis, three genotypes, namely PAU2, PAU4, and PAU16, were found superior in terms of mineral composition in microgreens and mature leaves of celery. Principal component and cluster analyses divide the genotypes into two different clusters on the basis of variability in mineral composition.

Nutritive and Phytochemical Composition of Aromatic Microgreen Herbs and Spices Belonging to the Apiaceae Family

Microgreens represent a new generation of food products, commonly used to garnish and embellish culinary dishes, and recently associated with an increasing interest in their nutraceutical and phytochemical profiles. Four Apiaceae species: Pimpinella anisum L. (anise), Anthriscus cerefolium L. (chervil), Carum carvi L. (caraway), and Anethum graveolens L. (dill) were assessed for fresh yield, macro- and microminerals, total chlorophylls, total ascorbic acid, carotenoids, polyphenols, and their antioxidant activity. Anise was the species yielding the most (2.53 kg m^-2) and having the highest lutein content (18.4 µg g^-1 dry weight (DW)). Chervil and dill were characterized by the highest total ascorbic acid content (~151 mg AA g^-1 fresh weight (FW)). The phenolic profile highlighted the presence of five flavonoid derivatives and 12 phenolic acid derivatives, with quinic acid derivatives being the most abundant phenols in the species tested. In addition, anise, caraway, and dill proved to be considerably rich in total polyphenols (~11056 μg g^-1 DW). Caraway and dill were characterized by the highest antioxidant activity measured by the DPPH and ABTS methods, whereas the FRAP method revealed caraway as having the highest antioxidant activity. Such results highlight the potential of Apiaceae species as an alternative to other families which are commonly used for microgreens production.

Indoor Vegetable Production: An Alternative Approach to Increasing Cultivation

As the world's population is increasing exponentially, human diets have changed to less healthy foods resulting in detrimental health complications. Increasing vegetable intake by both rural and urban dwellers can help address this issue. However, these communities often face the challenge of limited vegetable supply and accessibility. More so, open field vegetable production cannot supply all the vegetable needs because biotic and abiotic stress factors often hinder production. Alternative approaches such as vegetable production in greenhouses, indoor farms, high tunnels, and screenhouses can help fill the gap in the supply chain. These alternative production methods provide opportunities to use less resources such as land space, pesticide, and water. They also make possible the control of production factors such as temperature, relative humidity, and carbon dioxide, as well as extension of the growing season. Some of these production systems also make the supply and distribution of nutrients to crops easier and more uniform to enhance crop growth and yield. This paper reviews these alternative vegetable production approaches which include hydroponics, aeroponics, aquaponics and soilless mixes to reveal the need for exploring them further to increase crop production. The paper also discusses facilities used, plant growth factors, current challenges including energy costs and prospects.

A comparative study of phytochemical, antioxidant, anticarcinogenic, and antidiabetic potential of coriander (Coriandrum sativum L.): Microgreen and mature plant

Microgreens are immature edible leafy greens with a higher concentration of phytonutrients than in mature leaves, which makes them a novel functional food. This research featured antioxidant, anticarcinogenic, and antidiabetic properties of coriander microgreens. Aqueous and ethanolic extractions of coriander microgreens and mature leaves underwent a phytochemical analysis of antioxidant potential using the DPPH (2,2-diphenyl-1-picryl-hydrazyl-hydrate) free radical method and the ferric reducing antioxidant power (FRAP) assay. The analysis of antidiabetic and anticarcinogenic properties included the method of α-amylase enzyme inhibition and the MTT colorimetric assay. The screening test inferred the presence of alkaloids, terpenoids, glycosides, steroids, tannins, flavonoids, phenols, carbohydrates, and proteins in both microgreens and mature leaves. The quantitative analysis showed that the ethanolic extract of the microgreen sample exhibited higher total phenols. Total flavonoids, steroids, carbohydrates, and proteins were higher both in microgreen extracts, if compared with those of mature leaves. Ascorbic acid, chlorophyll-a, chlorophyll-b, and carotenoids demonstrated a more substantial presence in mature leaves. The gas chromatography-mass spectrometry (GC/MS) analysis of coriander microgreens revealed such bioactive compounds as thienopyrimidines, phenolic amide, imidazo pyridazine, phenolic constituents, and essential oil. Mature leaves were rich in phenolic compounds, steroids, terpenoids, essential oils, and fatty acid esters. All these substances are known for their therapeutic antioxidant, antidiabetic, and anticarcinogenic properties. The microgreen samples exhibited greater ferric reducing antioxidant power, α-amylase enzyme inhibition, and cytotoxicity activity at a lower concentration of extract than mature leaves. Coriander microgreens proved to have a promising antioxidant, anticarcinogenic, and antidiabetic potential and can be used in daily food additives.

Sensory Evaluation of Common Ice Plant (Mesembryanthemum crystallinum L.) in Response to Sodium Chloride Concentration in Hydroponic Nutrient Solution

Common ice plant (Mesembryanthemum crystallinum L.) is a novel edible plant with a succulent and savory flavor. The plants display prominent epidermal bladder cells (EBCs) on the surface of the leaves that store water and sodium chloride (NaCl). The plants have high nutritional value and are adapted to saline soils. Previous research has determined the impact of NaCl on the growth and mineral content of ice plant, but as NaCl has an impact on a food's sensory properties, an interesting question is whether saline growth media can affect the plant's taste and texture, and if this alters consumers' sensory response to ice plant. The objective of this study was to evaluate the sensory aspects of ice plant, as well as consumer liking in response to increasing NaCl concentration in hydroponic nutrient solution. Four-week-old seedlings of ice plant were transplanted into deep water culture (DWC) hydroponic systems and treated with five NaCl concentrations (0 M [control], 0.05 M, 0.10 M, 0.20 M, and 0.40 M NaCl). Eight-week-old plants (after four weeks of NaCl treatment) were harvested, and the middle leaves of each plant were sampled for consumer testing. A total of 115 participants evaluated various flavor, texture, and appearance aspects of ice plant and provided their liking ratings. The consumers were able to discriminate differences in salt intensity from the plants based on NaCl treatment in the hydroponic nutrient solution. Low NaCl concentrations (0.05-0.10 M) did not have obvious adverse effect on consumer liking, which aligns with the result of previous research that 0.05-0.10 M NaCl could largely stimulate the growth of ice plant. NaCl concentrations higher than 0.20 M are not recommended from both a production and consumer perspective. With increased NaCl level in plant samples, the consumers detected more saltiness, sourness, and fishiness, less green flavor, and similar levels of bitterness and sweetness. NaCl treatment had no effects on leaf appearance and texture, and the consumers' overall liking was mainly determined by flavor. Overall, ice plant presents some unique attributes (salty and juicy) compared to other edible salad greens; however, consumer awareness of ice plant is very low, and purchase intent is relatively low as well. Consumers picture ice plant being used mainly in salads and in restaurants.

Effect of Irrigation Water and Organic Fertilizer on Reducing Nitrate Accumulation and Boosting Lettuce Productivity

Accumulation of high level of nitrate (NO3−) in leaves is a serious issue for vegetable crops like lettuce (Lactuca sativa L.). Therefore, this study aimed to limit NO3− level by adjusting the balance between fertilization and irrigation program in lettuce. In a strip plot design with three replicates, lettuce plants were grown under four fertilizer treatments and three irrigation regimes. Three organic fertilizers (biochar, compost and vermicompost), in addition to mineral fertilizer, were used. The irrigation regimes were 60, 80 and 100% of crop evapotranspiration, ETc (ETc60, ETc80, and ETc100). Nitrogen (N), phosphorus (P) potassium (K) and organic matter (OM) in soil as well as yield, N, P, K and NO3− of lettuce were estimated. Findings showed that vermicompost or biochar (with any irrigation regime) as well as compost with irrigation by ETc60 were the effective combinations for increasing K content in soil after harvest. Under irrigation by ETc80 or ETc100, vermicompost or biochar were the efficient treatments for increasing lettuce yield equaling the farmer common practice (ETc100 x mineral fertilizer). Under irrigation by ETc60, mineral fertilizer or vermicompost showed the highest lettuce leaf content of K. Moreover, ETc60 or ETc80 x mineral fertilizer recorded the maximum NO3− content of lettuce leaves. The accumulation of nitrate in lettuce leaves owing to mineral fertilizer reached about 1.24 times than that of organic fertilizers. Compost x ETc80 or ETc100 showed the minimal NO3–N accumulation, hence, high relative reductions in NO3–N accumulation as compared to the common practice (ETc100 x mineral fertilizer) were observed. In conclusion, irrigation by 80% instead of 100% of crop evapotranspiration of organically fertilized lettuce (especially with vermicompost) could be adopted since such practice recorded high lettuce productivity with low NO3− content.

Glycerophospholipidomics of Five Edible Oleaginous Microgreens

Microgreens are a special type of vegetal product, born as a culinary novelty (traditionally used to garnish gourmet dishes) and then progressively studied for their potentially high content in nutraceuticals, like polyphenolic compounds, carotenoids, and glucosinolates, also in the perspective of implementing their cultivation in space stations/colonies. Among further potential nutraceuticals of microgreens, lipids have received very limited attention so far. Here, glycerophospholipids contained in microgreens of typical oleaginous plants, namely, soybean, chia, flax, sunflower, and rapeseed, were studied using hydrophilic interaction liquid chromatography (HILIC), coupled to high-resolution Fourier transform mass spectrometry (FTMS) or low-resolution collisionally induced dissociation tandem mass spectrometry (CID-MS²) with electrospray ionization (ESI). Specifically, this approach was employed to obtain qualitative and quantitative profiling of the four main classes of glycerophospholipids (GPL) found in the five microgreens, i.e., phosphatidylcholines (PC), phosphatidylethanolamines (PE), phosphatidylglycerols (PG), and phosphatidylinositols (PI). Saturated chains with 16 and 18 carbon atoms and unsaturated 18:X (with X = 1-3) chains emerged as the most common fatty acyl substituents of those GPL; a characteristic 16:1 chain (including a C═C bond between carbon atoms 3 and 4) was also found in some PG species. Among polyunsaturated acyl chains, the 18:3 one, likely referred mainly to α-linolenic acid, exhibited a relevant incidence, with the highest estimated amount (corresponding to 160 mg per 100 g of lyophilized vegetal tissue) found for chia. This outcome opens interesting perspectives for the use of oleaginous microgreens as additional sources of essential fatty acids, especially in vegetarian/vegan diets.

Sprouts and Microgreens-Novel Food Sources for Healthy Diets

With the growing interest of society in healthy eating, the interest in fresh, ready-to-eat, functional food, such as microscale vegetables (sprouted seeds and microgreens), has been on the rise in recent years globally. This review briefly describes the crops commonly used for microscale vegetable production, highlights Brassica vegetables because of their health-promoting secondary metabolites (polyphenols, glucosinolates), and looks at consumer acceptance of sprouts and microgreens. Apart from the main crops used for microscale vegetable production, landraces, wild food plants, and crops' wild relatives often have high phytonutrient density and exciting flavors and tastes, thus providing the scope to widen the range of crops and species used for this purpose. Moreover, the nutritional value and content of phytochemicals often vary with plant growth and development within the same crop. Sprouted seeds and microgreens are often more nutrient-dense than ungerminated seeds or mature vegetables. This review also describes the environmental and priming factors that may impact the nutritional value and content of phytochemicals of microscale vegetables. These factors include the growth environment, growing substrates, imposed environmental stresses, seed priming and biostimulants, biofortification, and the effect of light in controlled environments. This review also touches on microgreen market trends. Due to their short growth cycle, nutrient-dense sprouts and microgreens can be produced with minimal input; without pesticides, they can even be home-grown and harvested as needed, hence having low environmental impacts and a broad acceptance among health-conscious consumers.

The Nutritional Quality Potential of Microgreens, Baby Leaves, and Adult Lettuce: An Underexploited Nutraceutical Source

Interest in the cultivation of lettuce landraces is increasing because native varieties, as high-quality products, are particularly attractive to consumers. Lettuce is a popular leafy vegetable worldwide, and interest in the consumption of first leaves (microgreens) and seedlings (baby leaves) has grown due to the general belief that young plants offer higher nutritional value. The content of some bioactive compounds and antioxidants (chlorophylls, carotenoids, anthocyanins, ascorbic acid, phenols, antioxidant activity) was monitored in six lettuce landraces and five commercial varieties, and compared across three development stages: microgreen, baby, and adult. Ascorbic acid and phenolic contents were 42% and 79% higher, respectively, in the early stages than in adult lettuces, and red-leaf varieties (CL4 and L11) stood out. This finding agrees with lettuce’s marked antioxidant capacity and correlates with its pigment contents, especially anthocyanins. The nutritional value of adult lettuce is conditioned by its size, shape, and head structure as phytochemical concentrations are regulated by light. The low content of ascorbic acid, phenolics, and anthocyanins in crisphead lettuce (CL5) is a clear example (49, 67%, and 27% lower, respectively, than the adult mean). Our results indicate the wide variability of lettuces’ nutritional characteristics and emphasize that traditional varieties are a helpful source of agricultural biodiversity.

Short-Term Impact of Two Kinds of Vegetables to Exogenous Total Nitrate and Nitrite Intake: Is Antibacterial Mouthwash Influential?

Background:

Nitrate is a compound with adverse effects on human health that can exist also in vegetables. This study aimed to determine the intake of total nitrate/nitrite from lettuce and carrot as high and low nitrate content, respectively. Moreover, the effect of chlorhexidine mouthwash on the elimination of the nitrite level in saliva and urine was surveyed.

Methods:

This study was designed as a crossover based on the randomized selection method. Thirty-nine participants were divided into two groups; the lettuce and carrot juice consumers (control group). The case group was consumed these two vegetables, while they used antibacterial mouthwash. The background of nitrate/nitrite of the participants was determined before exposure. The intake of total nitrate and nitrite via lettuce and carrot juice consumption was investigated. The Griess colorimetric reaction was used for nitrate and nitrite determination in samples.

Results:

Total nitrate concentrations in case and control groups were detected 0.79 and 0.78 mM in saliva and 1.78 and 1.38 mM in urine after lettuce consumption, respectively. However, it was determined 1.55 and 2.43 mM in saliva and 2.92 and 3.04 mM in urine after carrot ingestion. Salivary nitrite concentration 0.53 mM was decreased to 0.45 mM after antibacterial mouthwash application (P-value <0.05).

Conclusions:

This study indicated that the intake of total nitrate/nitrite via leafy vegetables was higher than rooty ones. The chlorhexidine mouthwash is an appropriate recommendation to reduce the nitrite concentration in the human body for preventing the probable side effects of nitrate metabolites such as N-nitrosamines forming.

Continuous LED Lighting Enhances Yield and Nutritional Value of Four Genotypes of Brassicaceae Microgreens

The effect of continuous lighting (CL, 24 h) and light spectrum on growth and nutritional quality of arugula (Eruca sativa), broccoli (Brassica oleracea var. italic), mizuna (Brassica rapa. var. nipposinica), and radish (Raphanus sativus var. radicula) were investigated in growth chambers under light-emitting diode (LED) and fluorescent lighting. Microgreens were grown under four combinations of two photoperiods (16 h and 24 h) providing daily light integral (DLI) of 15.6 and 23.3 mol m^-2 day^-1, correspondingly) with two light spectra: LED lamps and fluorescent lamps (FLU). The results show that fresh and dry weights as well as leaf mass per area and robust index of harvested arugula, broccoli, mizuna, and radish seedlings were significantly higher under CL compared to 16 h photoperiod regardless of light quality. There were no visible signs of leaf photodamage. In all CL-treated plants higher chlorophyll a/b and carotenoid-to-chlorophyll ratios were observed in all plants except mizuna. CL treatment was beneficial for anthocyanin, flavonoid, and proline accumulation. Higher activities of antioxidant enzymes (catalase, superoxide dismutase, ascorbate peroxidase, and guaiacol peroxidase) were also observed in CL-treated plants. In most cases, the effects were more pronounced under LED lighting. These results indicate that plants under mild oxidative stress induced by CL accumulated more non-enzymatic antioxidants and increased the activities of antioxidant enzymes. This added nutritional value to microgreens that are used as functional foods providing health benefits. We suggest that for arugula, broccoli, mizuna, and radish, an LED CL production strategy is possible and can have economic and nutritional benefits.

Effect of end-of production continuous lighting on yield and nutritional value of Brassicaceae microgreens

The effect of continuous lighting applied in the end-of-production period on growth and nutritional quality of radish (Raphanus sativus var. radicula), broccoli (Brassica oleracea var. italic), mizuna (Brassica rapa. var. nipposinica) and arugula (Eruca sativa) was investigated in growth chambers under LED lighting. Microgreens were grown under 16 h photoperiod and 3 days before harvest half of plants were placed under continuous lighting conditions. Pre-harvest continuous lighting treatment increased yield, robustness index, and shorten time to harvest in radish, broccoli, mizuna and arugula microgreens. The end-of-production treatment has also led to higher content of compounds with antioxidative properties (flavonoids, proline) and increased the activity of antioxidant enzymes (CAT, APX, GPX) by inducing mild photooxidative stress. Increased antioxidative status added nutritional value to microgreens that can be used as functional foods providing health benefits. Pre-harvest treatment by continuous lighting is suggested as the practice than can allow producers to increase yield, aesthetic appeal, nutritional quality, and market value of Brassicacea microgreens.

Agronomic Biofortification of Cayenne Pepper Cultivars with Plant Growth-Promoting Rhizobacteria and Chili Residue in a Chinese Solar Greenhouse

Agronomic biofortification of horticultural crops using plant growth-promoting rhizobacteria (PGPR) under crop residue incorporation systems remains largely underexploited. Bacillus subtilis (B1), Bacillus laterosporus (B2), or Bacillus amyloliquefaciens (B3) was inoculated on soil containing chili residue, while chili residue without PGPR (NP) served as the control. Two hybrid long cayenne peppers, succeeding a leaf mustard crop were used in the intensive cultivation study. Net photosynthesis, leaf stomatal conductance, transpiration rate, photosynthetic water use efficiency, shoot and root biomass, and fruit yield were evaluated. Derivatives of folate, minerals, and nitrate contents in the pepper fruits were also assessed. B1 elicited higher net photosynthesis and photosynthetic water use efficiency, while B2 and B3 had higher transpiration rates than B1 and NP. B1 and B3 resulted in 27–36% increase in pepper fruit yield compared to other treatments, whereas B3 produced 24–27.5% and 21.9–27.2% higher 5-methyltetrahydrofolate and total folate contents, respectively, compared to B1 and NP. However, chili residue without PGPR inoculation improved fruit calcium, magnesium, and potassium contents than the inoculated treatments. ‘Xin Xian La 8 F1’ cultivar had higher yield and plant biomass, fruit potassium, total soluble solids, and total folate contents compared to ‘La Gao F1.’ Agronomic biofortification through the synergy of Bacillus amyloliquefaciens and chili residue produced better yield and folate contents with a trade-off in the mineral contents of the greenhouse-grown long cayenne pepper.

V, Tontang MT, Stobdan T, Sangwan S, Aski M, Singh A, Kumar RR, Tripathi K, Kumar S, Nair RM, Praveen S. Diversity in Phytochemical Composition, Antioxidant Capacities, and Nutrient Contents Among Mungbean and Lentil Microgreens When Grown at Plain-Altitude Region (Delhi) and High-Altitude Region (Leh-Ladakh), India

Mungbeans and lentils are relatively easily grown and cheaper sources of microgreens, but their phytonutrient diversity is not yet deeply explored. In this study, 20 diverse genotypes each of mungbean and lentil were grown as microgreens under plain-altitude (Delhi) and high-altitude (Leh) conditions, which showed significant genotypic variations for ascorbic acid, tocopherol, carotenoids, flavonoid, total phenolics, DPPH (1, 1-diphenyl-2-picrylhydrazyl), FRAP (ferric-reducing antioxidant power), peroxide activity, proteins, enzymes (peroxidase and catalase), micronutrients, and macronutrients contents. The lentil and mungbean genotypes L830 and MH810, respectively, were found superior for most of the studied parameters over other studied genotypes. Interestingly, for most of the studied parameters, Leh-grown microgreens were found superior to the Delhi-grown microgreens, which could be due to unique environmental conditions of Leh, especially wide temperature amplitude, photosynthetically active radiation (PAR), and UV-B content. In mungbean microgreens, total phenolics content (TPC) was found positively correlated with FRAP and DPPH, while in lentil microgreens, total flavonoid content (TFC) was found positively correlated with DPPH. The most abundant elements recorded were in the order of K, P, and Ca in mungbean microgreens; and K, Ca, and P in the lentil microgreens. In addition, these Fabaceae microgreens may help in the nutritional security of the population residing in the high-altitude regions of Ladakh, especially during winter months when this region remains landlocked due to heavy snowfall.

Exposure to Salinity and Light Spectra Regulates Glucosinolates, Phenolics, and Antioxidant Capacity of Brassica carinata L. Microgreens

The effect of salt treatment on Brassica carinata (BC) microgreens grown under different light wavelengths on glucosinolates (GLs) and phenolic compounds were evaluated. Quantifiable GLs were identified using ultra-high performance-quadrupole time of flight mass spectrometry. Extracts' ability to activate antioxidant enzymes (superoxide dismutase (SOD) and catalase (CAT)) was evaluated on human colorectal carcinoma cells (HCT116). Furthermore, BC compounds' ability to activate expression of nuclear transcription factor-erythroid 2 related factor (Nrf2) and heme-oxygenase-1 (HO-1) proteins was examined using specific antibodies on HCT116 cells. Sinigrin (SIN) was the abundant GLs of the six compounds identified and its content together with total aliphatic GLs increased in saline conditions. Fluorescent (FL) and blue plus red (B1R1) lights were identified as stable cultivation conditions for microgreens, promoting biomass and glucobrassicin contents, whereas other identified individual and total indole GLs behaved differently in saline and non-saline environments. Blue light-emitting diodes and FL light in saline treatments mostly enhanced SIN, phenolics and antioxidant activities. The increased SOD and CAT activities render the BC microgreens suitable for lowering oxidative stress. Additionally, activation of Nrf2, and HO-1 protein expression by the GLs rich extracts, demonstrate their potential to treat and prevent oxidative stress and inflammatory disorders. Therefore, effective salt treatments and light exposure to BC microgreens present an opportunity for targeted regulation of growth and accumulation of bioactive metabolites.

The role of emerging micro-scale vegetables in human diet and health benefits-an updated review based on microgreens

Increasing public concern about health has prompted humans to find new sources of food. Microgreens are young and immature plants that have been recently introduced as a new category of vegetables, adapting their production at the micro-scale. In this paper, the chemical compositions including micro-nutrients and some typical phytochemicals of microgreens are summarized. Their edible safety and potential health benefits are also reviewed. Microgreens play an increasingly vital role in health-promoting diets. They are considered good sources of nutritional and bioactive compounds, and show potential in the prevention of malnutrition and chronic diseases. Some strategies in the pre- or post-harvest stages of microgreens can be further applied to obtain better nutritional, functional, and sensorial quality with freshness and extended shelf life. This review provides valuable nutrient data and health information for microgreens, laying a theoretical foundation for people to consume microgreens more wisely, and providing great value for the development of functional products with microgreens.

Preharvest Nutrient Deprivation Reconfigures Nitrate, Mineral, and Phytochemical Content of Microgreens

While imparting gastronomic novelty and sensory delight, microgreens also constitute rudimentary leafy greens packed with nutrients and phytochemicals. As such, they comprise an upcoming class of functional foods. However, apart from bioactive secondary metabolites, microgreens also accumulate antinutritive agents such as nitrate, especially under conducive protected cultivation conditions. The current work examined nutrient deprivation before harvest (DBH), applied by replacing nutrient solution with osmotic water for six and twelve days, as a strategy for reducing microgreen nitrate levels in different species (lettuce, mustard, and rocket). The three species were sown on a peat-based substrate, cultivated in a controlled climate chamber, and harvested 18 days after sowing, when the first two true leaves emerged. DBH impact on major constituents of the secondary metabolome, mineral content, colorimetric, and yield traits was appraised. Nitrate and mineral content were determined through ion chromatography, phenolic composition through UHPLC-Q-Orbitrap HRMS, and carotenoid composition through HPLC-DAD. Nutrient deprivation was effective in reducing nitrate content; however, effective treatment duration differed between species and decline was more precipitous in nitrate hyperaccumulating species such as rocket. Quercetin and kaempferol glycosides were the flavonol glycosides most abundant in brassicaceous microgreens, whereas lettuce microgreens were steeped in caffeoyl quinic acid. DBH interacted with species as it increased the total phenolic content of lettuce, decreased that of rocket, but did not affect mustard. Further research to link changes in phenolic composition to the sensory and in vivo bioactive profile of microgreens is warranted. Notably, brief (≤6 days) DBH can be applied across species with moderate or no impact on the phenolic, carotenoid, and mineral composition of microgreens. Brief DBH applications also have limited impact on microgreens' yield and colorimetric traits hence on the commercial value of the product. They can therefore be applied for reducing microgreen nitrate levels without significantly impacting key secondary metabolic constituents and their potential bioactive role.

Shoot Production and Mineral Nutrients of Five Microgreens as Affected by Hydroponic Substrate Type and Post-Emergent Fertilization

As a new specialty crop with high market value, microgreens are vegetable or herb seedlings consumed at a young age, 7–21 days after germination. They are known as functional food with high concentrations of mineral nutrients and health beneficial phytochemicals. Microgreen industry lacks standardized recommendations on cultural practices including species/variety selection, substrate choice, and fertilization management. This study evaluated shoot growth and mineral nutrient concentrations in five microgreens including four Brassica and one Raphanus microgreens as affected by four hydroponic pad types and post-emergent fertilization in two experiments in January and February 2020. The five microgreens varied in their shoot height, fresh, dry shoot weights, and mineral nutrient concentrations with radish producing the highest fresh and dry shoot weights. Radish had the highest nitrogen (N) concentration and mustard had the highest phosphorus (P) concentrations when grown with three hydroponic pads except for hemp mat. Hydroponic pad type altered fresh, dry shoot weights, and mineral nutrients in tested microgreens. Microgreens in hemp mat showed the highest shoot height, fresh, dry shoot weights, and potassium (K) concentration, but the lowest N concentration in one or two experiments. One time post-emergent fertilization generally increased shoot height, fresh, dry shoot weights, and macronutrient concentrations in microgreens.

LED Enhances Plant Performance and Both Carotenoids and Nitrates Profiles in Lettuce

Recent studies show that vegetables at early stage of development contain higher amounts of phytonutrients and minerals, and lower amounts of nitrates than at fully developed stage. Nevertheless, the effects of some spectrum light on the carotenoid content of lettuce microgreens are unknown. Three different LED lamps were checked: (i) artificial white light (T0); (ii) continuous light-emitting diodes with longer blue-wavelength (T1), and (iii) continuous light-emitting diodes with longer red-wavelength (T2). Different lettuce cvs. were grown under the above described lamps. Plants were collected after 10, 15, 35 and 50 days from planting to produce sprouts, microgreens, initial baby leaf, and baby leaf, respectively. Response to different continuous spectrum lights related to productivity and nitrate content was variable for the different plants. Accumulation of nitrates at initial stages in plant tissues was clearly lower than at final stages of crop development, ranging from 50.2 to 73.4 mg 100 g1 fresh weight for T2. Lettuce consumption is preferable at microgreen stage in comparison with baby leaf stage. Nitrate amounts at microgreen stage were lower than in baby leaf stage, and this content was inversely correlated with carotenoid content, which in tissues was higher at microgreens stage influenced by LED.

Ontogenetic Variation in the Mineral, Phytochemical and Yield Attributes of Brassicaceous Microgreens

Microgreens constitute novel gastronomic ingredients that combine visual, kinesthetic and bioactive qualities. The definition of the optimal developmental stage for harvesting microgreens remains fluid. Their superior phytochemical content against mature leaves underpins the current hypothesis of significant changes in compositional profile during the brief interval of ontogeny from the appearance of the first (S1) to the second true leaf (S2). Microgreens of four brassicaceous genotypes (Komatsuna, Mibuna, Mizuna and Pak Choi) grown under controlled conditions and harvested at S1 and S2 were appraised for fresh and dry yield traits. They were further analyzed for macro- and micromineral content using inductively coupled plasma optical emission spectrometry (ICP-OES), carotenoid content using high-performance liquid chromatography with a diode-array detector (HPLC-DAD), volatile organic compounds using solid-phase microextraction followed by gas chromatography-mass spectrometry (SPME-GC/MS), anthocyanins and polyphenols using liquid chromatography-high resolution-tandem mass spectrometry (LC-MS/MS) with Orbitrap technology and for chlorophyll and ascorbate concentrations, well as antioxidant capacity by spectrophotometry. Analysis of compositional profiles revealed genotype as the principal source of variation for all constituents. The response of mineral and phytochemical composition and of antioxidant capacity to the growth stage was limited and largely genotype-dependent. It is, therefore, questionable whether delaying harvest from S1 to S2 would significantly improve the bioactive value of microgreens while the cost-benefit analysis for this decision must be genotype-specific. Finally, the lower-yielding genotypes (Mizuna and Pak Choi) registered higher relative increase in fresh yield between S1 and S2, compared to the faster-growing and higher-yielding genotypes. Although the optimal harvest stage for specific genotypes must be determined considering the increase in yield against reduction in crop turnover, harvesting at S2 seems advisable for the lower-yielding genotypes.

Quality Evaluation of Indoor-Grown Microgreens Cultivated on Three Different Substrates

The microgreens are innovative products in the horticultural sector. They are appreciated by consumers thanks to their novelty and health-related benefits, having a high antioxidant concentration. This produce can be adopted for indoor production using hydroponic systems. The aim of the present work was to investigate the influence of three growing media (vermiculite, coconut fiber, and jute fabric) on yield and quality parameters of two basil varieties (Green basil—Ocimum basilicum L., Red basil—Ocimum basilicum var. Purpurecsens) and rocket (Eruca sativa Mill.) as microgreens. Microgreens were grown in floating, in a Micro Experimental Growing (MEG®) system equipped with LED lamps, with modulation of both energy and spectra of the light supplied to plants. Results showed high yield, comprised from 2 to 3 kg m−2. Nutritional quality varied among species and higher antioxidant compounds were found in red basil on vermiculite and jute. Coconut fiber allowed the differentiation of crop performance in terms of sucrose and above all nitrate. In particular, our results point out that the choice of the substrate significantly affected the yield, the dry matter percentage and the nitrate concentration of microgreens, while the other qualitative parameters were most influenced by the species.

Small Functional Foods: Comparative Phytochemical and Nutritional Analyses of Five Microgreens of the Brassicaceae Family

Microgreens are the seedlings of herbs and vegetables which are harvested at the development stage of their two cotyledonary leaves, or sometimes at the emergence of their rudimentary first pair of true leaves. They are functional foods, the consumption of which is steadily increasing due to their high nutritional value. The species of the Brassicaceae family are good sources of bioactive compounds, with a favorable nutritional profile. The present study analyzed some phytochemical compounds with nutritional values, such as chlorophylls, polyphenols, carotenoids, anthocyanins, ascorbic acid, total and reducing sugars, and the antioxidant activity of five Brassicaceae species: broccoli (Brassica oleracea L.), daikon (Raphanus raphanistrum subsp. sativus (L.) Domin), mustard (Brassica juncea (L.) Czern.), rocket salad (Eruca vesicaria (L.) Cav.), and watercress (Nasturtium officinale R.Br.). Broccoli had the highest polyphenol, carotenoid and chlorophyll contents, as well as a good antioxidant ability. Mustard was characterized by high ascorbic acid and total sugar contents. By contrast, rocket salad exhibited the lowest antioxidant content and activity. The essential oil (EO) composition of all of these species was determined in order to identify their profile and isothiocyanates content, which are compounds with many reported health benefits. Isothiocyanates were the most abundant group in broccoli (4-pentenyl isothiocyanate), mustard (allyl isothiocyanate), and watercress (benzyl isothiocyanate) EOs, while rocket salad and daikon exhibited higher contents of monoterpene hydrocarbons (myrcene) and oxygenated diterpenes (phytol), respectively. Broccoli microgreens exhibited the overall best nutritional profile, appearing as the most promising species to be consumed as a functional food among those analyzed.

Fertilization and Pre-Sowing Seed Soaking Affect Yield and Mineral Nutrients of Ten Microgreen Species

Microgreens, vegetable or herb seedlings consumed at a young growth stage, are considered to be a functional food with high concentrations of mineral nutrients and healthy beneficial bioactive compounds. The production of microgreens has been increasing in recent years. Vegetable growers are interested in growing microgreens as a new specialty crop due to their high market value, popularity, and short production cycles. However, there is a lack of research-based crop-specific recommendations for cultural practices including fertilization, pre-sowing seed treatments, and their effects on nutritional facts of microgreens. Ten microgreen species were evaluated for their shoot growth and mineral nutrient concentrations as affected by one-time post-emergence fertilization and pre-sowing seed soaking in two repeated experiments, from November 2018 to January 2019, in a greenhouse. The microgreen species varied in fresh and dry shoot weights, shoot height, visual rating, as well as macro- and micro-nutrient concentrations. Fertilization with a general-purpose soluble fertilizer (20-20-20 with micronutrients) at a rate of 100 mg·L−1 nitrogen (N) increased fresh shoot weight, and macro- and micro-nutrient concentrations in one or both experiments, with the exception of decreasing concentrations of calcium (Ca), magnesium (Mg), and manganese (Mn). Seed soaking consistently decreased fresh or dry shoot weight and nutrient concentrations when there was a significant effect.

Plant growth promotion effect of plasma activated water on Lactuca sativa L. cultivated in two different volumes of substrate

Plasma activated water (PAW) can represent an alternative to chemical fertilizers in agriculture. The effects of PAW treatment applied in two concentrations (1.5 or 3.0 mg L-1 NO3-) on some morphological, physiological, biochemical parameters and yield of Lactuca sativa L. grown in two different pot volumes (400 or 3200 cm3) were investigated in this study. The results showed that both PAW concentrations did not influence the germination, once the process was initiated. Positive effects of the treatments were registered on the length of radicle and hypocotyls of lettuce at a concentration of 1.5 mg L-1 NO3- (PAW I), the chlorophyll content was significantly increased at a concentration of 3.0 mg L-1 NO3- (PAW II) and bigger pot volume, also the foliar weight and area. No significant differences between the treated and untreated plants were recorded for the root weight, leaf length and width. The dry weight was significantly higher for the lettuce treated with PAW I and II grown in big volume pots at 57 days after transplanting (DAT) and small volume pots at 64 DAT. The nitrites content of the lettuce grown in big pots was lower than of the lettuce grown in small pots, regardless of the PAW treatment. Contrary, the nitrates content was higher in the lettuce grown in big pots (up to 36.4 mg KNO3/g DW), compared to small pots (under 0.3 mg KNO3/g DW).

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).

Do nitrogen sources and molybdenum affect the nutritional quality and nitrate concentrations of hydroponic baby leaf lettuce?

Lettuce is one of the most popular vegetables, and the market niche of the baby leaf variety is expanding. The manner in which nitrogen (N) is supplied and the available concentration of the micronutrient molybdenum (Mo) affect N metabolism, with reflects on the nutritional quality of that vegetable. Here, two Mo concentrations (0.06 and 0.12 mg/L) and four proportions (%) of nitrate (NO3 - )/ammonium (NH4 + )(100/0, 75/25, 50/50, and 25/75) were supplied to hydroponic baby leaf lettuce floating type to evaluate their effects on plant growth and leaf mineral and NO3 - compositions. Shoot dry mass did not differ among the different treatments, although fresh mass was lower in treatments with larger proportions of NH4 + . Higher leaf concentrations of NO3 - were observed in plants treated with 100% N-NO3 - , but they were still below tolerable limits for human health. The enzyme nitrate reductase was not found to be sensitive to the nitrogen sources or to Mo concentrations. N proportions and Mo concentrations differently affected macro- (C, N, P, K, Ca, Mg, and S) and micronutrients (Cu, Fe, Mn, Mo, and Zn) leaf concentrations. Although treatment with 100% N-NO3 - favored higher mineral concentrations in lettuce leaves, the addition of 25% N-NH4 + allowed fresh mass production with the lowest NO3 - concentrations. As such, and considering the healthy reduction of NO3 - consumption by humans and the maintenance of plant productivity, the 75/25 NO3 - /NH4 + proportion is recommended for the hydroponic cultivation of baby leaf var. Mimosa lettuce. PRACTICAL APPLICATION: We demonstrate a direct link between the constitution of nutrient solution with nitrate accumulation by hydroponic lettuce and indicate the best source of N as well as the concentration of Mn to healthy reduction of NO3 - consumption by humans and the maintenance of plant productivity.

In Vitro Bioaccessibility and Bioavailability of Iron from Mature and Microgreen Fenugreek, Rocket and Broccoli

Iron deficiency is a global epidemic affecting a third of the world's population. Current efforts are focused on investigating sustainable ways to improve the bioavailability of iron in plant-based diets. Incorporating microgreens into the diet of at-risk groups in populations could be a useful tool in the management and prevention of iron deficiency. This study analysed and compared the mineral content and bioavailability of iron from microgreen and mature vegetables. The mineral content of rocket, broccoli and fenugreek microgreens and their mature counterparts was determined using microwave digestion and ICP-OES. Iron solubility and bioavailability from the vegetables were determined by a simulated gastrointestinal in vitro digestion and subsequent measurement of ferritin in Caco-2 cells as a surrogate marker of iron uptake. Iron contents of mature fenugreek and rocket were significantly higher than those of the microgreens. Mature fenugreek and broccoli showed significantly (p < 0.001) higher bioaccessibility and low-molecular-weight iron than found in the microgreens. Moreover, iron uptake by Caco-2 cells was significantly higher only from fenugreek microgreens than the mature vegetable. While all vegetables except broccoli enhanced FeSO₄ uptake, the response to ferric ammonium citrate (FAC) was inhibitory apart from the mature rocket. Ascorbic acid significantly enhanced iron uptake from mature fenugreek and rocket. Microgreen fenugreek may be bred for a higher content of enhancers of iron availability as a strategy to improve iron nutrition in the populace.

Variation in Macronutrient Content, Phytochemical Constitution and In Vitro Antioxidant Capacity of Green and Red Butterhead Lettuce Dictated by Different Developmental Stages of Harvest Maturity

Rising life expectancy and the demanding modern lifestyle drive the growing appeal of healthy and balanced diets centered on vegetable and fruit consumption. Functional, phytonutrient-packed and principally raw food is in high demand. Microgreens constitute such a novel functional food that combines a high sensory and bioactive value, which invites comparison to their mature-leaf counterparts. For this purpose, a controlled environment chamber experiment was carried out to compare the mineral, phytochemical and antioxidant capacity attributes of two-pigmented Lactuca sativa L. var. capitata cultivars (green and red Salanova^®) harvested at the microgreens and the mature-leaf stage. Macronutrients were assessed through ion chromatography, while carotenoids and polyphenols were assessed and quantified through HPLC-DAD and UHPLC-Q-Orbitrap HRMS, respectively. Calcium and magnesium were higher in microgreens irrespective of the cultivar; conversely, phosphorous, potassium and nitrate where higher in mature leaves. All pigments including chlorophyll, lutein and β-carotene augmented at advanced maturity stage and were more concentrated in the red pigmented cultivar at both stages. Total polyphenols accumulated more densely in red Salanova, particularly in the microgreens stage; whereas, in green Salanova, the accumulation was significant but less pronounced in the mcirogreens stage. Chlorogenic acid, quercetin malonyl glucoside, rutin and coumaroyl quinic acid were the most concentrated phenolic acids in microgreens, while feruloyl tartaric acid was predominant in mature leaves. Finally, when a high carotenoids content is sought, mature lettuce leaves should be the prime culinary choice, whereas high polyphenolic content is dictated by both the cultivar and the harvest stage, with red Salanova microgreens being the most nutrient-packed choice.

Selenium Biofortification Impacts the Nutritive Value, Polyphenolic Content, and Bioactive Constitution of Variable Microgreens Genotypes

Selenium (Se) is considered essential for human nutrition as it is involved in the metabolic pathway of selenoproteins and relevant biological functions. Microgreens, defined as tender immature greens, constitute an emerging functional food characterized by overall higher levels of phytonutrients than their mature counterparts. The nutraceutical value of microgreens can be further improved through Se biofortification, delivering Se-enriched foods and potentially an enhanced content of bioactive compounds. The current study defined the effect of sodium selenate applications at three concentrations (0, 8, and 16 μM Se) on the bioactive compounds and mineral content of coriander, green basil, purple basil, and tatsoi microgreens grown in soilless cultivation. Analytical emphasis was dedicated to the identification and quantification of polyphenols by UHPLC-Q-Orbitrap-HRMS, major carotenoids by HPLC-DAD, and macro micro-minerals by ICP-OES. Twenty-seven phenolic compounds were quantified, of which the most abundant were: Chlorogenic acid and rutin in coriander, caffeic acid hexoside and kaempferol-3-O(caffeoyl) sophoroside-7-O-glucoside in tatsoi, and cichoric acid and rosmarinic acid in both green and purple basil. In coriander and tatsoi microgreens, the application of 16 μM Se increased the total phenols content by 21% and 95%, respectively; moreover, it improved the yield by 44% and 18%, respectively. At the same Se dose, the bioactive value of coriander and tatsoi was enhanced by a significant increase in rutin (33%) and kaempferol-3-O(feruloyl)sophoroside-7-O-glucoside (157%), respectively, compared to the control. In green and purple basil microgreens, the 8 μM Se application enhanced the lutein concentration by 7% and 19%, respectively. The same application rate also increased the overall macroelements content by 35% and total polyphenols concentration by 32% but only in the green cultivar. The latter actually had a tripled chicoric acid content compared to the untreated control. All microgreen genotypes exhibited an increase in the Se content in response to the biofortification treatments, thereby satisfying the recommended daily allowance for Se (RDA-Se) from 20% to 133%. The optimal Se dose that guarantees the effectiveness of Se biofortification and improves the content of bioactive compounds was 16 μM in coriander and tatsoi, and 8 μM in green and purple basil.

Phenolic Constitution, Phytochemical and Macronutrient Content in Three Species of Microgreens as Modulated by Natural Fiber and Synthetic Substrates

The present study examined the modulatory effects of natural fiber substrates (agave fiber, coconut fiber and peat moss) and synthetic alternatives (capillary mat and cellulose sponge) on the nutritive and phytochemical composition of select microgreens species (coriander, kohlrabi and pak choi) grown in a controlled environment. Polyphenols were analyzed by UHPLC-Q-Orbitrap-HRMS, major carotenoids by HPLC-DAD, and macro-minerals by ion chromatography. Microgreens grown on peat moss had outstanding fresh and dry yield but low dry matter content. Natural fiber substrates increased nitrate and overall macro-mineral concentrations in microgreens compared to synthetic substrates. The concentrations of chlorophylls, carotenoids and ascorbate were influenced primarily by species. On the contrary, variability in polyphenols content was wider between substrates than species. Out of twenty phenolic compounds identified, chlorogenic acid and quercetin-3-O-rutinoside were most abundant. Hydroxycinnamic acids and their derivatives accounted for 49.8% of mean phenolic content across species, flavonol glycosides for 48.4% and flavone glycosides for 1.8%. Peat moss provided optimal physicochemical conditions that enhanced microgreens growth rate and biomass production at the expense of phenolic content. In this respect, the application of controlled stress (eustress) on microgreens growing on peat moss warrants investigation as a means of enhancing phytochemical composition without substantial compromise in crop performance and production turnover. Finally, nitrate deprivation practices should be considered for microgreens grown on natural fiber substrates in order to minimize consumer exposure to nitrate.

Microgreens: Consumer sensory perception and acceptance of an emerging functional food crop

Microgreens are an emerging functional food crop with promise for sustainably diversifying global food systems, facilitating adaptations to urbanization and global climate change, and promoting human health. Previous work suggests microgreens have high nutritional quality, low environmental impacts, and broad consumer acceptance. For better reception into the global food system and increased per capita consumption, research is needed to elucidate consumer acceptance of various microgreens species, including factors contributing to their acceptance or lack thereof. Using a consumer panel (n = 99), this study evaluated consumer sensory perception and acceptability of six microgreens species (arugula, broccoli, bull's blood beet, red cabbage, red garnet amaranth, and tendril pea), and potential drivers and barriers to consumer acceptance. All microgreens species received high mean liking scores for acceptability by consumers (means ranged from highly acceptable to slightly acceptable), with more distinct differences across microgreens species for flavor and overall acceptability, which appeared to be driven by specific sensory properties. Data from principal component analysis demonstrated that high acceptability scores were associated with higher intent to purchase microgreens and negatively associated with food neophobia. Participants indicated that factors such as knowledge and familiarity of microgreens, cost, access/availability, freshness/shelf life, among other factors, influence their intention to purchase microgreens. These findings suggest that further integration of microgreens into the global food system will be met with high consumer acceptability, but needs to be aligned with enhanced consumer education regarding microgreens, as well as considerations of cost, availability/access, and freshness/shelf life. PRACTICAL APPLICATION: Researchers investigated consumer sensory perception and acceptability of six microgreens species (arugula, broccoli, bull's blood beet, red cabbage, red garnet amaranth, and tendril pea), and potential drivers and barriers to consumer acceptance. All microgreens tested had high consumer acceptability, but certain factors such as sensory perception and food neophobia impacted their acceptability. Additionally, participants indicated that factors such as knowledge, access and availability, cost, freshness, and shelf life may impact the purchasing of microgreens and thus are important factors to consider for further integration of this emerging functional food crop into the global food system.