Yield, Bioactive Compounds, and Antioxidant Potential of Twenty-Three Diverse Microgreen Species Grown Under Controlled Conditions

Abstract

Selecting suitable crop species is crucial for optimizing the productivity and nutritional content of microgreens. In this study, twenty-three diverse microgreen species, grown under controlled conditions, were analyzed for yield, bioactive compounds, and antioxidant activities. The microgreens were cultivated on a peat substrate in a controlled environment, with a growth period of 6 to 20 days from planting to harvest. Conditions were maintained at 25 ± 2 °C, a 16 h photoperiod, CO₂ concentration of 1000 ppm, relative humidity of 60 ± 2%, and the LED light was set at 330 μmol/m²/s PPFD. Results from the analysis revealed that the yield, bioactive compounds, and antioxidant potential differed significantly among the twenty-three microgreen species. Unfortunately, the superior microgreens exhibiting greater values for all studied traits could not be identified. However, the principal component analysis (PCA) clustered red radish, rat-tailed radish, and Chinese kale microgreens, which were high in both yield and bioactive compounds. In contrast, red holy basil and lemon basil microgreens had high levels of these compounds but low yields. Additionally, a high level of anti-tyrosinase activity was observed in garland chrysanthemum, Chinese mustard, and Chinese cabbage microgreens. Therefore, these microgreen species can be utilized individually or in varying ratios to produce bioactive compounds in different concentrations that are suitable for various applications. The information presented in this study provides valuable insights for health-conscious consumers and growers for selecting superior species with functional implications.

1. Introduction

The UN’s 2015 Sustainable Development Goals (SDGs) focus on global challenges. SDG 2: Zero Hunger is crucial for ending hunger and malnutrition, promoting sustainable agriculture, and boosting incomes for smallholder farmers, especially in developing countries. Addressing these challenges involves developing resilient food systems, adopting innovative agricultural technologies, and ensuring equitable growth. Overcoming obstacles such as climate change and urbanization is vital for achieving global food security and a sustainable future for everyone [1]. By 2023, the global population of undernourished individuals reached 735 million, marking a rise of 122 million compared to 2019. Approximately 45 million children under the age of five experience stunting or wasting [2,3]. Lack of nutritional awareness and limited access to fresh fruit and vegetables lead to poor diet quality, which causes disorders like scurvy and osteoporosis as well as many non-communicable diseases [4,5]. A healthy diet, typically composed of nutrient-dense foods, whole grains, and a variety of colorful fruits and vegetables, is considered an effective strategy for preventing cardiometabolic diseases and reducing premature mortality [5,6,7]. Microgreens have recently gained popularity across various cuisines due to their ability to meet consumers’ preferences for novelty and palatability while offering high nutritional value [5,7,8].

Microgreens, often called “vegetable confetti”, are immature edible greens initially used by Californian chefs to garnish dishes, adding a vibrant touch to culinary presentations [5,9,10]. The microgreen market has seen rapid growth and is projected to capture significant shares in the global market, with a compound annual growth rate expected to be up to 12–20% [11]. Microgreens are highly attractive products due to rising demand driven by emerging gastronomic trends [12]. Moreover, microgreens require low production inputs and have a short growth cycle, allowing them to produce multi-crops compared to the mature vegetable stage [13,14,15]. Depending on the species, they can be harvested just above the roots between 7 and 21 days after planting (DAP), when the cotyledons are fully formed or the first true leaves have emerged [10,14,15,16,17]. Despite their small size, these microgreens have intense sensory attributes, such as flavor, texture, aroma, appearance, and vivid colors [14]. Microgreens are not only rich in macro- and micro-elements such as Mn, Ca, and Zn [7,10] but they are also abundant in bioactive components such as ascorbic acid, phylloquinones, α-tocopherol, β-carotene, phenolic antioxidants, carotenoids, anthocyanins, and glucosinolates [15,16,18,19]. These nutritional constituents are recognized for their significant potential to enhance physiologically active and biological activities such as anticancer, antimicrobial, antiestrogenic, and antioxidant properties [20,21]. As a result, microgreens are well-suited for use as healthy functional foods or superfoods in the next generation [14,22].

The agronomic characteristics, sensory attributes, and phytochemicals of microgreens are primarily influenced by genetic material, growing conditions, and cultivation management practices are the main pre-harvest factors [20,23,24]. The choice of a particular species and varieties becomes important since each of them has these biometric characteristics [25,26,27]. Commonly exploited species belong to the families Brassicaceae, Asteraceae, Chenopodiaceae, Lamiaceae, Apiaceae, Amaryllidaceae, Amaranthaceae, and Cucurbitaceae [9,26,28]. Additionally, cereals, legumes, oil plants, and herbs are frequently grown as microgreens. Both local and commercial varieties, as well as wild relatives and ancient species, can be used for all these categories [20,22,29]. However, numerous microgreen species, which were collected in tropical zones, are still not assessed for their growth performance and health promoting constituents. Thailand, located in Southeast Asia, inherits rich biodiversity and traditional plant species. This biodiversity can be used to drive sustainable grassroots economic growth, supporting the country’s bioeconomy, according to the BCG agenda [30]. Therefore, the objective of this study was to evaluate yield, bioactive compounds, and antioxidant potential of twenty-three diverse microgreens species grown under controlled conditions. This is the first time that Thailand’s microgreens have been elucidated in terms of their growth and phytochemical profiles, particularly phenolic acids, flavonoids, and tyrosinase inhibitory activity, providing valuable information on superior genotypes for both growers and consumers.

2. Materials and Methods

2.1. Seed Materials and Microgreens Production Under Controlled Conditions

The seeds of all 23 species were obtained from a local agricultural store (Pathum Thani, Thailand), with more than 85% germination percentage and without any seed treatment (

Table 1. Details of the vegetables are used as microgreens.

No.	Common Name	Scientific Name	Family	Seeding Rate/Tray (g) 1/	Days After Planting (DAP)	Biomass-to-Seed Ratio
1	Red amaranth	Amaranthus viridis L.	Amaranthaceae	9	6	6.77
2	Leaf celery	Apium graveolens var. secalinum.	Apiaceae	9	16	4.51
3	Coriander	Coriandrum sativum L.	Apiaceae	25	13	1.47
4	Dill	Anethum graveolens L.	Apiaceae	8	13	2.69
5	Garland chrysanthemum	Chrysanthemum coronarium	Asteraceae	9	13	3.15
6	Sunflower	Helianthus annuus L.	Asteraceae	30	6	3.62
7	Indian mustard	Brassica juncea L. Czern.	Brassicaceae	8	6	13.29
8	Chinese mustard	B. juncea L var. rugosa	Brassicaceae	8	6	8.86
9	Chinese cabbage	B. rapa L. subsp. pekinensis	Brassicaceae	8	6	13.63
10	Daikon radish	Raphanus sativus L. var. longipinnatus	Brassicaceae	25	6	10.83
11	Red radish	R. sativus L. var. radicula	Brassicaceae	25	6	10.66
12	Rat-tailed radish	R. caudatus L. var. caudatus Alef	Brassicaceae	25	6	9.11
13	Cabbage	B. oleracea L. var. capitata	Brassicaceae	8	6	11.26
14	Cauliflower	B. oleracea var. botrytis	Brassicaceae	8	6	11.58
15	Broccoli	B. oleracea L. var. italica Plenck.	Brassicaceae	8	6	11.27
16	Chinese kale	B. oleracea L. var. alboglabra	Brassicaceae	15	8	9.73
17	Water convolvulus	Ipomoea aquatica Forssk.	Convolvulaceae	50	9	4.00
18	Thai water convolvulus	I. aquatica Forssk.	Convolvulaceae	60	8	2.53
19	Sugar pea	Pisum sativum L.	Fabaceae	100	9	1.08
20	Red holy basil	Ocimum tenuiflorum L.	Lamiaceae	8	20	2.68
21	Lemon basil	O. × africanum L.	Lamiaceae	10	16	4.15
22	Okra	Abelmoschus esculentus Moench.	Malvaceae	40	9	5.81
23	Roselle	Hibiscus sabdariffa L.	Malvaceae	40	6	2.06

^1/ Tray size: 50 × 35 × 8 cm³ (l × w × h).

). The seeds were first surface sterilized with 0.5% NaOCl (v/v) for 10 min and then thoroughly washed with distilled water [31]. Subsequently, the seeds were sown in seedling trays of cell size 50 × 35 × 8 cm³ with three replicates. According to Dubey et al. [32], the quantity of seed required per m² (seed density) directly depends upon the seed weight of each microgreen species (Table 1). The growing medium used was a sterilized peat substrate with a pH of 5.5–6 (Klasmann-TS3, Geeste, Germany) rich in essential plant nutrients and commonly used for microgreen production [32,33]. A 2.5 cm-thick layer of growing medium was consistently used across all crop species, and sterile water was applied to it before planting [33]. The soaked seeds were evenly distributed on the prepared bed of the growing medium and then covered with a similar mixture to a depth of approximately 1 cm. The trays containing the seeds were placed on stainless steel growing racks in a single vertical layer and irrigated with sterile water thrice or four times daily using a hand sprayer. No nutrients were supplied throughout the growing period due to the short growth cycle of microgreens [32]. Growing conditions were a constant temperature of 25 ± 2 °C, 16 h photoperiod, CO₂ concentration of 1000 ppm, relative air humidity (RHs) of 60 ± 2%, and LED light intensity at 330 ± 1 µmol/m²/s PPED (1154*15.8*1.0-LM-20S1B, Grows Laboratory, Bangkok, Thailand) [34]. Temperature and relative humidity were monitored using a data logger (HOBO, OnSet Data Logging Solutions, Bourne, MA, USA). Each type of microgreen was harvested individually at the first true leaf stage. The harvesting process involved carefully cutting the stems approximately 1.0 cm above the growing medium using clean scissors. Microgreens were weighed, and the biomass-to-seed ratio was calculated as the ratio of the weight of seeds used per m² to the weight of biomass produced per m² [33]. Subsequently, samples were immediately deep-frozen in liquid nitrogen to stop enzymatic activity, then lyophilized until dry. The dried samples were weighed, and the percentage of dry matter was calculated using the following equation [35].

$$\mathrm{P}\mathrm{e}\mathrm{r}\mathrm{c}\mathrm{e}\mathrm{n}\mathrm{t}\mathrm{a}\mathrm{g}\mathrm{e} \mathrm{o}\mathrm{f} \mathrm{d}\mathrm{r}\mathrm{y} \mathrm{m}\mathrm{a}\mathrm{t}\mathrm{t}\mathrm{e}\mathrm{r} (\mathrm{\%})={\displaystyle \frac{\mathrm{d}\mathrm{r}\mathrm{y} \mathrm{w}\mathrm{e}\mathrm{i}\mathrm{g}\mathrm{h}\mathrm{t}}{\mathrm{f}\mathrm{r}\mathrm{e}\mathrm{s}\mathrm{h} \mathrm{w}\mathrm{e}\mathrm{i}\mathrm{g}\mathrm{h}\mathrm{t}}}\times 100$$

Finally, the samples were finely ground in a sample mill (Pulverisette 14, Fritsch, Idar-Oberstein, Germany), sieved through a 60-mesh screen, thoroughly mixed, and stored at −20 °C for subsequent analysis.

2.2. Sample Extraction and Determination of Antioxidants and Their Activities

The dried samples were extracted as described by Jirakiattikul [36], using a 1:3 w/v ratio with 95% ethanol over a three-day period. Maceration was performed three times. The resulting extracts were combined, filtered, and evaporated to dryness using a rotary evaporator (Buchi Rotavapor^® R-300, Flawil, Switzerland) until a pellet was obtained. The crude extract was analyzed for total phenolic content (TPC) using the Folin–Ciocalteu colorimetric method described in Folin and Ciocalteu [37], whereas total flavonoid content (TFC) followed from Kubola et al. [38]. A microplate reader (Power Wave XS, Biotek, CA, USA) was used to analyze both antioxidants at 510 and 765 nm absorbances, respectively. TPC and TFC were expressed on a dry weight basis as mg gallic acid equivalent per gram of dry weight (mg GAE/g DW) and mg quercetin equivalent per g of dry weight (mg QE/g DW), respectively.

Antioxidant activity was analyzed using a 2,2′-azino bis-3-ethylbenzthiazoline-6-sulphonic acid (ABTS) radical scavenging activity assay followed from Re et al. [39], whereas 1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assay followed from Brand-Williams et al. [40]. Absorbance was also measured in a microplate reader at 520 and 734 nm for DPPH and ABTS radical scavenging activity assays, respectively. The inhibition of both free radicals was expressed as µmol of Trolox equivalents per gram of dry weight (µmol TE/g DW).

2.3. Determination of Phenolic Acids and Flavonoids

Phenolic acid and flavonoid compositions were analyzed following the protocol of Mizzi et al. [41] with modifications. Briefly, reversed phase HPLC analysis of both compositions were performed using a Shimadzu system (Shimadzu Co., Ltd., Tokyo, Japan) equipped with a binary pump (mod. LC-20AC pump) and a diode array detector (mod. SPD-M20A). The HPLC separation was performed by an Inert-Sustain^® C18 column (250 mm × 4.6 mm, 5 μm; GL Sciences Inc., Tokyo, Japan). Operating conditions were as follows: flow rate of 0.5 mL/min, column temperature of 5 °C, injection volume of 20 μL, and a detection wavelength of 350–600 nm. The mobile phase consisted of a combination of A (acetonitrile) and B (orthophosphoric, pH 2). The linear gradient was from 95% to 80% B (v/v) at 15 min, to 70% B at 20 min, to 65% B at 30 min, to 60% B at 35 min, to 50% B at 40 min, to 30% B at 52 min and to 95% B at 60 min, and was returned to the initial condition by 10 min. The detection wavelengths for hydroxybenzoic acids, hydroxycinnamic acids, and flavonoids were 280, 320, and 370 nm, respectively. These compounds in the extracted samples were identified based on the retention time and spectrum of their respective standards. The results for the phenolics and flavonoids were expressed as micrograms per g of dry weight (mg/g of DW).

2.4. Tyrosinase Inhibitory Assay

The tyrosinase inhibitory activity of the crude extract was assessed following the slightly modified protocol of Nurrochmad et al. [42]. Mushroom tyrosinase (E.C. 1.14.18.1) was used as the enzyme, L-1,4-dihydroxyphenylalanine (L-DOPA) as the substrate, and kojic acid as the standard inhibitor. Dopachrome formation was measured at 475 nm using a UV/Vis spectrophotometer (EZ Read-2000, Fisher Scientific Co., Loughborough, UK). The tyrosinase inhibitory activity was obtained using the following equation.

$$\mathrm{t}\mathrm{y}\mathrm{r}\mathrm{o}\mathrm{s}\mathrm{i}\mathrm{n}\mathrm{a}\mathrm{s}\mathrm{e} \mathrm{i}\mathrm{n}\mathrm{h}\mathrm{i}\mathrm{b}\mathrm{i}\mathrm{t}\mathrm{o}\mathrm{r}\mathrm{y} \mathrm{a}\mathrm{c}\mathrm{t}\mathrm{i}\mathrm{v}\mathrm{i}\mathrm{t}\mathrm{y} (\mathrm{\%})={\displaystyle \frac{{\mathrm{A}}_{475} \mathrm{c}\mathrm{o}\mathrm{n}\mathrm{t}\mathrm{r}\mathrm{o}\mathrm{l}-{\mathrm{A}}_{475} \mathrm{s}\mathrm{a}\mathrm{m}\mathrm{p}\mathrm{l}\mathrm{e}}{{\mathrm{A}}_{475} \mathrm{c}\mathrm{o}\mathrm{n}\mathrm{t}\mathrm{r}\mathrm{o}\mathrm{l}}}\times 100$$

where A₄₇₅ control is the absorbance of blank DMSO; A₄₇₅ sample is the absorbance of samples.

2.5. Experimental Design and Statistical Analysis

The experiment was arranged in a completely randomized design with three replications. Data were analyzed using one-way ANOVA, and mean comparisons were conducted using LSD at a 0.05 significance level, using the Statistix software (version 10.0, Analytical Software, Tallahassee, FL, USA). Scaled data were used to perform principal component analysis (PCA) and correlation analysis of yield, bioactive compounds, and antioxidant activities, and the results were visualized using GraphPad^® [43].

3. Results

3.1. Morphology, Yield, and Percentage of Dry Matter

The appearance of 23 microgreens, which were grown under controlled conditions, is shown in Figure 1. The color of almost all the microgreens was green, except for the celery microgreen, which was yellowish green. The duration from planting to harvesting mature microgreens at the first true leaf stage varied among the 23 species of microgreens examined (Table 1). Twelve crop species (red amaranth, sunflower, Indian mustard, Chinese mustard, Chinese cabbage, daikon radish, red radish, rat-tailed radish, cabbage, cauliflower, broccoli, and roselle) were harvested 6 DAP, two species (Chinese kale and Thai water convolvulus) at 8 DAP, three species (water convolvulus, sugar pea, and okra) at 9 DAP, three species (coriander, dill, and garland chrysanthemum) at 13 DAP, two species (celery and lemon basil) at 16 DAP, and red holy basil at 20 DAP. The biomass produced exceeded the weight of the seeds used for planting, resulting in a biomass-to-seed ratio greater than one (Table 1). The highest biomass-to-seed ratio was observed in Chinese cabbage microgreen, whereas sugar pea microgreen had the lowest. The harvested microgreens were weighed to determine the fresh yield (FW) per seedling tray (0.175 m²). The highest yield was observed in daikon radish microgreen and the lowest in red holy basil microgreen (

Table 2. Yield, bioactive compounds, and their activities of 23 microgreens species grown under controlled conditions.

No. 1/	FW 2/	PDM	TPC	TFC	Antioxidant Activities (mg TE/g DW)		TIA
	(g/tray)	(%)	(mg GAE/g DW)	(mg QE/g DW)	ABTS	DPPH	(%)
1	60.93 ± 1.52 3/	1.70 ± 0.00 i	21.57 ± 0.25 j	30.29 ± 1.61 i	17.37 ± 0.88 kl	26.24 ± 0.89 g	10.00 ± 1.47 fg
2	40.58 ± 1.29 m	6.21 ± 0.64 c–g	48.89 ± 0.5 c	55.04 ± 0.08 e	21.82 ± 0.71 ij	41.28 ± 0.39 de	21.25 ± 1.68 d
3	36.7 ± 1.53 n	6.51 ± 0.49 c–f	33.19 ± 3.38 g	64.56 ± 0.56 d	10.97 ± 0.28 m	10.19 ± 2.05 jk	20.33 ± 1.18 d
4	21.52 ± 1.57 p	5.74 ± 0.26 d–h	13.94 ± 0.92 k	63.27 ± 0.08 d	8.25 ± 1.38 m	8.61 ± 0.89 k	10.16 ± 0.98 fg
5	28.33 ± 1.92 o	6.41 ± 0.74 c–g	42.56 ± 1.12 e	55.07 ± 0.18 e	28.44 ± 1.48 h	52.29 ± 0.40 c	47.56 ± 1.19 a
6	108.73 ± 1.64 h	12.30 ± 0.47 a	16.59 ± 1.25 k	20.93 ± 1.40 l	18.76 ± 1.94 jk	16.53 ± 0.95 i	6.09 ± 1.95 h
7	106.33 ± 1.95 h	4.56 ± 0.15 h	41.77 ± 0.35 ef	49.24 ± 2.01f	36.59 ± 0.66 d–f	32.80 ± 0.19 f	15.4 ± 0.10 e
8	70.87 ± 1.39 k	6.41 ± 0.12 c-g	28.43 ± 1.81 h	22.62 ± 1.04 kl	40.38 ± 4.87 bc	15.03 ± 4.68 i	36.08 ± 1.47 c
9	109.06 ± 2.66 h	4.95 ± 0.35 gh	33.24 ± 2.01 g	43.83 ± 2.25 g	22.31 ± 1.09 i	15.30 ± 0.06 i	41.24 ± 1.48 b
10	270.66 ± 1.66 a	6.34 ± 0.54 c–g	25.95 ± 0.30 hi	26.50 ± 2.82 j	37.46 ± 5.06 c–e	20.74 ± 3.88 h	15.71 ± 0.42 e
11	266.59 ± 1.50 b	6.64 ± 0.40 c–e	43.64 ± 0.40 de	64.16 ± 1.69 d	44.33 ± 1.09 a	41.88 ± 0.32 de	1.87 ± 0.47 j
12	227.75 ± 2.25 d	7.26 ± 0.38 c	49.74 ± 0.58 c	92.70 ± 0.16 a	32.97 ± 0.49 g	32.91 ± 0.93 f	3.74 ± 0.08 i
13	90.1 ± 1.79 i	5.32 ± 0.70 e–h	69.05 ± 7.22 a	42.38 ± 0.48 g	38.60 ± 2.53 cd	44.38 ± 4.27 d	9.40 ± 0.63 g
14	92.63 ± 2.53i	5.36 ± 0.62 e–h	38.69 ± 0.10 f	65.29 ± 2.41 d	35.11 ± 1.58 e–g	40.03 ± 1.51 e	9.17 ± 0.09 g
15	90.13 ± 1.71 i	10.50 ± 0.70 b	53.69 ± 2.17 b	85.93 ± 1.77 b	40.29 ± 0.14 bc	38.39 ± 2.23 e	20.83 ± 0.87 d
16	145.95 ± 4.02 g	6.67 ± 0.76 c–e	46.27 ± 1.21 cd	62.79 ± 2.50 d	32.22 ± 1.30 g	32.73 ± 0.39 f	8.06 ± 1.56 g
17	200.17 ± 1.57 e	5.05 ± 0.79 f–h	33.98 ± 0.68 g	52.22 ± 1.12 ef	14.94 ± 0.07 l	25.76 ± 1.51 g	16.05 ± 1.74 e
18	151.53 ± 2.29 f	6.26 ± 0.68 c–g	43.68 ± 1.98 de	75.77 ± 2.58 c	24.16 ± 1.40 i	68.52 ± 2.10 b	20.36 ± 1.50 d
19	108.01 ± 2.46 h	9.80 ± 1.15 b	21.32 ± 0.46 j	25.53 ± 2.50 jk	17.1 ± 2.01 kl	13.83 ± 0.80 ij	0.29 ± 0.17 j
20	21.47 ± 2.1 p	7.03 ± 0.54 cd	48.83 ± 1.01 c	78.75 ± 1.69 c	43.27 ± 0.95 ab	75.23 ± 0.39 a	11.78 ± 0.62 f
21	41.54 ± 3.32 m	6.53 ± 0.85 c–e	49.35 ± 1.46 c	83.75 ± 2.50 b	33.84 ± 1.02 fg	53.59 ± 3.35c	3.46 ± 1.08 i
22	232.45 ± 3.09 c	5.68 ± 0.83 d–h	27.78 ± 0.90 h	34.4 ± 3.95 h	9.23 ± 0.25 m	13.85 ± 0.19 ij	20.05 ± 1.88 d
23	82.53 ± 2.39 j	6.76 ± 0.71 c–e	22.81 ± 1.23 ij	26.47 ± 1.03 j	35.45 ± 1.10 d–g	22.80 ± 4.84 gh	3.32 ± 0.51 i
C.V. (%)	1.94	13.66	5.38	3.54	6.86	6.73	7.67

^1/ The entry numbers of microgreens match those in Table 1. ^2/ FW, fresh weight; PDM, percentage of dry matter; TPC, total phenolic content; TFC, total flavonoid content; ABTS, ABTS radical scavenging activity; DPPH, DPPH radical scavenging activity; TIA, tyrosinase inhibitory activity. ^3/ Means ± SD within each column sharing different letters are significantly different at p ≤ 0.05 by LSD.

). The percentage of dry matter (PDM) in microgreens ranged from 1.70 to 12.30% (Table 2). Among them, the sunflower microgreen had the highest PDM and the red amaranth microgreen possessed the lowest.

3.2. Bioactive Compounds, Antioxidant, and Tyrosinase Inhibitory Activities

In the study, total phenolic content (TPC), total flavonoid content (TFC), and antioxidant and tyrosinase inhibitory activities of 23 microgreens were determined and are shown in Table 2. Cabbage microgreen had the highest TPC, followed by broccoli, rat-tail radish, lemon basil, celery, and red holy basil microgreens. Dill microgreen had the lowest TPC but there was no discernible difference with the sunflower microgreen. The highest TFC was observed in the rat-tailed radish microgreen, whereas the sunflower microgreen was the lowest. Red radish and red holy basil microgreens showed the highest ABTS radical scavenging activity, whereas the coriander microgreen had the lowest. Moreover, red holy basil microgreen also showed the highest DPPH radical scavenging activity. Coriander microgreen showed the lowest antioxidant activity, while the okra microgreen showed no significant difference. In addition, garland chrysanthemum microgreen showed the highest tyrosinase inhibitory activity; the lowest was measured in red radish microgreen, but there was no significance with sugar pea microgreen.

Two sub-groups of phenolic acid (hydroxybenzoic and hydroxycinnamic acids) and flavonoid compositions of the 23 microgreens are shown in

Table 3. Contents of phenolic acids and flavonoids (µg/g DW) of 23 diverse microgreen species grown under controlled conditions.

No. 1/	Hydroxybenzoic Acids					Hydroxycinnamic Acids				Flavonoids
	GA 2/	PCA	CGA	PHBA	VA	CFA	FA	p-CA	CA	RT	QE
1	n.d.	n.d.	0.11 ± 0.00 k	n.d.	n.d.	n.d.	0.11 ± 0.00 i	n.d.	n.d.	0.02 ± 0.00 l	n.d.
2	0.53 ± 0.00 kl 3/	0.36 ± 0.01 g	2.47 ± 0.23 fg	0.09 ± 0.00 f	0.05 ± 0.00 g–i	1.28 ± 0.08 d	2.77 ± 0.2 ef	0.09 ± 0.00 g	0.13 ± 0.00 e	0.82 ± 0.16 g	0.30 ± 0.01 i–k
3	0.24 ± 0.00 q	n.d.	0.73 ± 0.04 ij	n.d.	n.d.	0.35 ± 0.04 hi	0.35 ± 0.02 hi	n.d.	0.02 ± 0.00 jk	0.13 ± 0.02 kl	0.58 ± 0.05 h
4	0.24 ± 0.00 q	0.18 ± 0.01 lm	0.41 ± 0.02 jk	n.d.	0.06 ± 0.01 gh	0.12 ± 0.01 hi	0.54 ± 0.06 g–i	0.07 ± 0.01 gh	0.03 ± 0.00 j	0.39 ± 0.05 h–j	1.03 ± 0.08 g
5	0.51 ± 0.03 lm	0.26 ± 0.01 ij	2.51 ± 0.07 fg	0.05 ± 0.00 g	0.06 ± 0.00 gh	1.55 ± 0.05 d	2.36 ± 0.94 f	0.08 ± 0.00 g	0.09 ± 0.00 f	0.24 ± 0.01 h–l	0.51 ± 0.06 h
6	0.36 ± 0.00 o	0.27 ± 0.00 hi	0.69 ± 0.06 i–k	0.04 ± 0.01 g–i	0.08 ± 0.01 e	0.27 ± 0.04 hi	0.89 ± 0.10 g–i	0.11 ± 0.00 f	0.06 ± 0.00 hi	0.12 ± 0.00 kl	0.12 ± 0.00 j–m
7	0.54 ± 0.00 k	0.22 ± 0.00 i–k	2.81 ± 0.08 f	n.d.	0.06 ± 0.00 fg	1.52 ± 0.02 d	2.82 ± 0.25 ef	0.08 ± 0.00 gh	0.08 ± 0.00 fg	0.33 ± 0.05 h–k	0.32 ± 0.04 ij
8	0.62 ± 0.01 i	0.23 ± 0.00 ij	1.1 ± 0.16 hi	n.d.	0.07 ± 0.00 f	0.92 ± 0.14 ef	0.99 ± 0.03 g–i	0.08 ± 0.00 gh	0.05 ± 0.00 i	0.13 ± 0.00 kl	0.12 ± 0.00 k–m
9	0.13 ± 0.00 r	n.d.	0.38 ± 0.06 jk	n.d.	n.d.	0.26 ± 0.01 hi	0.21 ± 0.00 hi	n.d.	0.01 ± 0.00 jk	0.05 ± 0.00 l	0.06 ± 0.00 lm
10	0.70 ± 0.00 h	0.27 ± 0.00 hi	1.41 ± 0.09 h	n.d.	0.08 ± 0.00 e	0.75 ± 0.02 fg	1.06 ± 0.06 gh	0.09 ± 0.00 g	0.04 ± 0.00 i	0.23 ± 0.03 h–l	0.21 ± 0.02 j–l
11	2.09 ± 0.01 a	0.95 ± 0.07 a	10.08 ± 0.45 a	0.22 ± 0.03 b	0.22 ± 0.00 a	5.66 ± 0.19 a	5.88 ± 0.39 d	0.31 ± 0.00 a	0.41 ± 0.00 a	3.03 ± 0.36 b	2.86 ± 0.11 c
12	1.09 ± 0.01 d	0.77 ± 0.02 c	6.12 ± 0.67 c	0.19 ± 0.01 c	0.11 ± 0.00 bc	3.03 ± 0.27 b	6.13 ± 0.26 cd	0.23 ± 0.01 bc	0.31 ± 0.00 b	3.44 ± 0.24 a	4.1 ± 0.30 a
13	1.13 ± 0.03 c	0.95 ± 0.04 a	8.05 ± 0.46 b	0.27 ± 0.04 a	0.10 ± 0.00 d	2.78 ± 0.63 b	8.2 ± 0.56 a	0.21 ± 0.01 c	0.33 ± 0.02 b	0.21 ± 0.02 i–l	0.22 ± 0.01 j–l
14	0.50 ± 0.01 m	0.19 ± 0.00 k–m	2.11 ± 0.08 g	n.d.	0.05 ± 0.00 gh	1.22 ± 0.19 de	2.32 ± 0.55 f	0.06 ± 0.00 hi	0.07 ± 0.00 gh	1.43 ± 0.19 f	1.36 ± 0.13 f
15	1.18 ± 0.04 b	0.82 ± 0.04 b	5.97 ± 0.77 c	0.22 ± 0.00 b	0.11 ± 0.00 cd	2.93 ± 0.11 b	3.57 ± 1.11 e	0.23 ± 0.01 b	0.32 ± 0.00 b	2.49 ± 0.07 d	3.28 ± 0.13 b
16	0.34 ± 0.00 o	0.63 ± 0.03 d	5.15 ± 0.57 d	0.14 ± 0.00 d	0.11 ± 0.00 bc	2.90 ± 0.10 b	6.81 ± 1.08 bc	0.16 ± 0.01 d	0.26 ± 0.00 c	0.42 ± 0.02 hi	1.10 ± 0.15 g
17	0.58 ± 0.01 j	0.22 ± 0.00 j–l	2.16 ± 0.10 g	n.d.	0.06 ± 0.00 gh	1.50 ± 0.13 d	0.96 ± 0.05 gh i	0.07 ± 0.00 gh	0.06 ± 0.00 hi	0.45 ± 0.05 h	0.46 ± 0.03 hi
18	1.03 ± 0.01 e	0.57 ± 0.01 e	4.89 ± 0.57 d	0.15 ± 0.00 d	0.12 ± 0.00 b	2.86 ± 0.33 b	2.79 ± 0.96 ef	0.15 ± 0.00 d	0.25 ± 0.01 c	2.72 ± 0.20 c	2.8 ± 0.15 c
19	0.42 ± 0.01 n	0.30 ± 0.04 h	0.85 ± 0.05 h–j	n.d.	0.10 ± 0.01 d	0.40 ± 0.03 hi	0.83 ± 0.05 gh i	0.11 ± 0.01 f	0.05 ± 0.01 i	0.18 ± 0.00 j–l	0.16 ± 0.00 j–m
20	0.87 ± 0.00 f	0.50 ± 0.00 f	4.29 ± 0.53 e	0.11 ± 0.01 e	0.08 ± 0.00 e	2.23 ± 0.15 c	7.26 ± 0.23 b	0.13 ± 0.01 e	0.21 ± 0.00 d	1.75 ± 0.01 e	1.94 ± 0.12 e
21	0.82 ± 0.01 g	0.56 ± 0.01 e	0.76 ± 0.06 ij	0.13 ± 0.00 d	0.08 ± 0.00 e	2.14 ± 0.12 c	1.34 ± 0.13 g	0.15 ± 0.01 d	0.22 ± 0.00 d	1.66 ± 0.08 e	2.51 ± 0.04 d
22	0.40 ± 0.00 n	0.15 ± 0.00 m	0.76 ± 0.07 ij	n.d.	0.04 ± 0.00 i	0.45 ± 0.05 gh	0.61 ± 0.03 g–i	0.05 ± 0.00 j	0.02 ± 0.00 j	0.17 ± 0.01 kl	0.18 ± 0.00 j–m
23	0.28 ± 0.00 p	0.17 ± 0.00 m	0.71 ± 0.06 i–k	n.d.	0.05 ± 0.00 hi	0.41 ± 0.03 hi	0.61 ± 0.02 g–i	0.05 ± 0.00 ij	0.02 ± 0.00 j	0.11 ± 0.00 kl	0.11 ± 0.00 lm
C.V. (%)	0.49	8.25	11.91	3.87	12.56	12.05	8.53	8.65	7.25	13.18	9.04

^1/ The entry numbers of microgreens match those in Table 1. ^2/ GA, gallic acid; PCA, protocatechuic acid; CGA, chlorogenic acid; PHBA, p-hydroxybenzoic acid; VA, vanillic acid; CFA, caffeic acid; FA, ferulic acid; p-CA, p-coumaric acid; CA, cinnamic acid; RT, rutin; QE, quercetin; n.d.; not detect. ^3/ Means ± SD within each column sharing different letters are significantly different at p ≤ 0.05 by LSD.

. Red radish microgreen had the highest contents of gallic, protocatechuic, chlorogenic, vanillic, caffeic, p-coumaric, and cinnamic acids, whereas the highest contents of protocatechuic, p-hydroxybenzoic, and ferulic acids were also found in cabbage microgreen. The highest contents of flavonoids, including rutin and quercetin, were found in rat-tailed radish microgreen. Moreover, broccoli microgreen exhibited a high content of gallic, protocatechuic, p-hydroxybenzoic, caffeic, p-coumaric, and cinnamic acids, as well as quercetin. On the other hand, red amaranth microgreen contains only chlorogenic acid, ferulic acid, and rutin.

3.3. Principal Component Analysis (PCA) and Correlation

A comprehensive analysis of the yield, bioactive compounds, and their antioxidant properties of 23 microgreens was conducted through PCA of the mean values of all replicate variables discussed above. In total, 18 studied variables were included in PCA, of which four principal components with eigenvalues greater than 1 were retained for further analysis. The first four PCs were explained with 85.72% of the total variance, with PC1 accounting for 61.91%, PC2 for 10.57%, PC3 for 7.34%, and PC4 for 5.90% (Table S1). The biplot revealed a positive correlation between PC1 and all studied characteristics, except for tyrosinase inhibitory activity, which exhibited a negative correlation with this principal component. Moreover, PC2 was positively correlated with TPC, TFC, and DPPH radical scavenging activity, while it was negatively correlated with both fresh and dry yield (Figure 2a). Eight microgreens, included red radish, rat-tailed radish, cabbage, broccoli, Chinese kale, Thai water convolvulus, red holy basil, and lemon basil, were positioned on the positive side of PC1 in the upper and lower right quadrants of the PCA score plot. These microgreens were characterized by higher levels of all bioactive compounds and their antioxidant potential compared to other microgreens (Figure 2b). Moreover, red radish, rat-tailed radish, and Chinese kale also had high yields, both in fresh and dry forms. The upper left quadrant included red amaranth, celery, coriander, garland chrysanthemum, Indian mustard, Chinese mustard, Chinese cabbage, and cauliflower microgreens, which all exhibited good tyrosinase inhibitory activity. Finally, the lower left quadrant comprised microgreens such as dill, sunflower, daikon radish, water convolvulus, sugar pea, okra, and roselle, which were characterized by low levels of all the studied traits.

It is worth noting that the DPPH radical scavenging activity showed a positive correlation with both the TPC and TFC, whereas the ABTS radical scavenging activity positively correlated only with TPC (Figure 3). However, significant correlations with antioxidant activity were obtained for specific phenolic compounds and flavonoids. For example, all the phenolics and flavonoids, except for vanillic acid and quercetin, showed a positive correlation with both antioxidant activities. Vanillic acid showed a positive correlation with the ABTS radical scavenging activity but not with the DPPH radical scavenging activity, whereas the quercetin exhibited the opposite pattern. However, there was no significant correlation between tyrosinase inhibitory activity and the other studied traits across microgreen species.

4. Discussion

The global production of high-quality microgreens is exhibiting a sustained upward trend, driven by their health and nutritional benefits, as well as the rapid adoption of indoor farming practices across both small- and commercial-scale production systems [32]. In controlled-environment cultivation systems, the growth of microgreens and their content of bioactive compounds are influenced by several pre-harvest factors, including species, growing conditions (e.g., temperature, CO₂ concentrations, relative humidity, and nutrient solution), and light spectral quality and intensity [27,44,45]. According to previous studies, the optimal conditions for achieving high growth and quality in microgreen cultivation within temperate regions include a light intensity of 100 to 300 µmol/m²/s PPFD, a night/day temperature range of 17–20 °C, CO₂ concentrations between ambient levels (approximately 400 ppm) and 1000 ppm, and a relative humidity range of 50–70% [13,32,45]. However, the light quantity and temperature, which differ from those used in this study, were treated as fixed variables and were selected based on our previous research and other relevant studies to meet the specific requirements of tropical crop microgreens [34,46]. Therefore, this study focused on crop species as a variable influencing the growth, nutritional values, and phytochemical composition of microgreens.

Appearance quality is often an important factor governing the growers’ concerns and consumer acceptance [16,47]. Of all the aspects of appearance quality, the color of microgreens is a significant attribute that enhances sensory quality [48], boosts popularity [49], and can increase consumption [50,51]. The color of microgreens can vary widely, allowing for the distinguish of species that are green, yellow, red, crimson, or multicolored [52]. The colors of microgreens can vary based on the crop species; green-leafed species are the most common in the present study (Figure 1). According to Ying et al. [53], larger leaves with a darker green color are generally more attractive for green-leaf microgreen species, although this may differ based on personal preferences. In addition, we observed that red-leafed species, including red amaranth, red radish, and red holy basil microgreens, exhibit a dark green color in their hypocotyl and leaf parts. These microgreens were grown under high light intensity (330 ± 1 µmol/m²/s PPED), which reduced their red-purple color value. According to Flores et al. [54], they found that the red color of red kale microgreen decreased under medium and high light intensities, indicating a lack of red-purple pigments. Oppositely, a reduced red color value indicates increased proportions of anthocyanins in reddish-purple crops [55]. Moreover, the effect of light intensity on vegetable color can interact with other factors, such as light spectrum, species [56], and photoperiod [57].

Microgreens, due to their short production cycle and specialized growth under controlled conditions, have attracted greenhouse growers and small-scale farmers, thereby generating income for them [32]. Consequently, they are able to produce microgreens in multiple crop cycles, unlike mature vegetables [13]. This study found that the duration from planting to harvesting mature microgreens at the first true leaf stage varied significantly across the crop species evaluated (Table 1). Among all the microgreens, those from the Brassicaceae microgreen had their true leaves fully developed in 6–8 days. According to previous suggestions, microgreens from the Brassicaceae family should be harvested on day 7th [9]. On the other hand, microgreens from the Apiaceae and Lamiaceae microgreens showed comparatively slower growth, with true leaves emerging in 13–20 days. However, the growth period for these microgreens was generally shorter than the 22-day period reported for Brassicaceae microgreens, such as jute, kohlrabi, radish, and Swiss chard, which are usually harvested later at the cotyledon or second true leaf stages [20].

Fresh yield is regarded as one of the most crucial factors in microgreen growing business because biomass production is a major limitation in microgreen plant factories [58]. Among different crop species, the fresh yield of microgreens was significantly different, consistent with previous studies [9,13,20,33,35]. In this study, three out of five higher yield microgreens were obtained in the Brassicaceae family, but these yields were lower than previously reported for microgreens grown under controlled conditions (Table 2). For instance, the fresh yield of daikon radish microgreens examined in the present study averaged 270.66 ± 1.66 g/tray or 1.55 ± 0.01 kg/m², compared to 5.97 ± 1.27 kg/m² reported for radish microgreens by Kyriacou et al. [20]. This difference likely reflects variations in genotype and growing conditions, despite similar planting densities (140 vs. 158 g/m²). On the other hand, the Apiaceae, Asteraceae, and Lamiaceae microgreens had lower yields compared to other families, as reported in previous studies [20]. Microgreens with both long hypocotyls and larger leaves, which have a high fresh weight content, exhibited a higher PDM than species with short hypocotyls and narrow leaves.

The findings of this study demonstrated that all microgreen species exhibited a biomass-to-seed ratio greater than one, indicating that the biomass produced exceeded the weight of the seeds used for planting (Table 1). This rate is crop-specific and crucial for determining the optimal seeding density. According to previous research that has reported consistently high biomass-to-seed conversion efficiencies in microgreens [33]. Brassicaceae microgreens exhibited the highest biomass-to-seed ratios, ranging from 9.11 to 13.29, whereas substantially lower ratios were observed in microgreens from other botanical families. Especially, sugar pea microgreen had the lowest biomass-to-seed ratio (1.08). This study confirmed that large-seeded species, due to their greater seed weight, require a higher seeding rate per tray. Additionally, a comprehensive evaluation of microgreen yield should consider seed cost, as seeds are required in substantial quantities and represent a major component of total production expenses [35]. The high biomass-to-seed ratio, particularly in Brassicaceae microgreens, contributes to the low production cost, as it indicates efficient seed utilization. This becomes particularly important given the rapid growth of microgreen industry and the rising diversity of species and varieties cultivated as microgreens [28,35].

Most microgreens with a high TPC were from the Brassicaceae (cabbage, broccoli, and rat-tailed radish) and Apiaceae (red holy basil and lemon basil) microgreens (Table 2), consistent with findings from other studies [58,59]. In contrast, Agarwal et al. [60] also reported a higher TPC of Malvaceae than Brassicaceae microgreens. Various intrinsic and extrinsic factors can account for variations in the TPC among different microgreens. These factors include species, growth conditions, maturity at harvest, and postharvest storage conditions [59,61]. Moreover, the TPC of rat-tailed radish, water convolvulus, dill, and lemon microgreens was found to be 1.50 to 11.33 times higher than in our previous studies under similar growing conditions [34]. This significant difference can be attributed to the use of different seed lots and varieties within the same species in those studies. The typical daily intake of phenolic acids recommended for humans is approximately 200 mg, though this can vary based on individual dietary habits and preferences [62]. Based on our findings and the variations in phenolic compound levels among different microgreens, consuming approximately 10 to 70 g (considering 80% moisture content) of these microgreens daily could satisfy the average person’s daily phenolic needs. Moreover, TPC values can serve as a predictor for evaluating the overall eating quality and flavor-related sensory attributes of microgreens [16]. Thus, microgreen species with high levels of TPC should be promising in terms of eating quality, a hypothesis that will be confirmed in future studies. The TFC levels followed a similar pattern to the TPC levels, ranging from 20.93 to 92.70 mg QE/g DW. Higher TFC levels were observed in the Brassicaceae (rat-tailed radish and broccoli) and Apiaceae (lemon basil) microgreens compared to previously studied microgreens (ca 0.10 mg QE/g DW) [59,60,62,63], reporting that roselle and sunflower microgreens had a higher TFC than other species. In this study, significant differences in ABTS and DPPH radical scavenging activities were also observed among different species of microgreens, indicating that these variations are species dependent. Red holy basil microgreens exhibited the highest antioxidant activities in both ABTS and DPPH radical scavenging activities, whereas radish microgreen showed the highest activity only in the DPPH radical scavenging activity. According to our previous study, red holy basil microgreen exhibited the highest antioxidant activities in both ABTS and DPPH radical scavenging activities compared to other species under the same conditions [34]. It should be highlighted that red holy basil microgreen recorded the highest TPC and antioxidant activities in both ABTS and DPPH radical scavenging activities. In addition, Ghoora et al. [62] reported that roselle microgreen exhibited the highest DPPH radical scavenging assay and TPC levels, but our study found them to be low to medium in this species. The best TIA was noted garland chrysanthemum microgreen, followed by Chinese mustard and Chinese cabbage microgreens. Our findings are also supported by Tomas et al. [64], who reported that kale and red cabbage microgreens exhibited notable TIA compared to kohlrabi and purple radish microgreens. These microgreens, with high TIA, could be selected as a new source of novel whitening phytochemical compounds from natural products, a trend that has recently gained increasing attention.

In this study, Brassicaceae microgreens were good sources of phenolic acids (Table 3), consistent with previous studies [21,64,65]. On the other hand, red amaranth microgreen contained only chlorogenic and ferulic acids, which are the dominant presence of both phenolic compound groups. Flavonoids, one of the most diverse and widespread groups of natural phenolics, include 58 flavonoids and their derivatives identified in vegetables [66]. Significant variations were noted in the primary flavonoid compositions among different species and varieties of microgreens [20,23,65]. From the results of this study, flavonoids including rutin and quercetin were measured in these microgreens, with quercetin being present in higher contents than rutin. Many studies have reported that quercetin has stronger anti-inflammatory and antioxidant activities than rutin, which may be attributed to the presence of glycoside moieties [67]. The Brassicaceae microgreens exhibited higher levels of flavonoids compared to other families. Especially, rat-tailed radish microgreen had the highest content of both rutin and quercetin. Huang et al. [68] reported that Brassicaceae microgreens are a rich source of various flavonoids, with kaempferol, apigenin, quercetin, puerarin, and catechin being the predominant ones. Our results indicate that Brassicaceae microgreens are excellent sources of bioactive compounds, making them a valuable addition to a healthy diet.

Many studies have recommended that principal component analysis (PCA) is an effective approach for collectively representing variations in microgreens across multiple productivity and quality traits, influenced by various cultivation factors [20,24,69]. In this study, the PCA was performed to obtain a summarized view of the relationships between the diverse 23 microgreen species evaluated in terms of their yield, bioactive compounds, and antioxidant potential (Figure 2). As a result, the clustering pattern among microgreen species and the studied characteristics was better visualized, and the quality of the PCA loading and score plots improved, as indicated by the high percentage of total variance (72.48%) accounted for by the first two PCs. The main conclusive evidence provided with respect to the eight species included red radish, rat-tailed radish, cabbage, broccoli, Chinese kale, Thai water convolvulus, red holy basil, and lemon basil, which were superior species over other species in terms of yield and antioxidant properties, except for anti-tyrosinase activity. Conversely, the implications of low-yield but high-bioactive microgreens, including red holy basil and lemon basil, suggest a trade-off between quantity and nutritional value. While these microgreens may not produce high yields compared to Brassicaceae crops, their elevated bioactive compound content could make them valuable for specialized applications, such as functional foods, nutraceuticals, or dietary supplements. Additionally, the anti-tyrosinase activity varied among the microgreen species found in the upper left quadrant. For instance, garland chrysanthemum, Chinese mustard, and Chinese radish microgreen had high levels of activity, whereas red amaranth, coriander, Indian mustard, and cauliflower microgreen processed medium levels. Therefore, the PCA representations support the main conclusion from the tabulated results (Table 2 and Table 3) that, although superior microgreen species possess several productive and nutritional traits, further research is warranted. Specifically, the study should clarify the interactive effects of different microgreen varieties, seed lots, and various pre-harvest management strategies—such as cold plasma treatment and the use of plant biostimulants—on the sensory characteristics and quality traits of selected high-performing species.

Both DPPH and ABTS radical scavenging activities showed a positive correlation with TPC and TFC, but ABTS radical scavenging activity was not correlated with TFC (Figure 3). According to this result, antioxidant activity was contributed mainly by TPC and was highly influenced by the number and position of the hydrogen-donating hydroxyl groups [20]. Additionally, all phenolic compounds, except vanillic acid, exhibited a positive correlation with both antioxidant activities, suggesting their potential as indicators of the antioxidant potency in microgreens. However, it is crucial to support these in vitro findings with clinical studies that consider factors such as bioavailability and metabolism of phenolic compounds to better assess the overall antioxidant impact of microgreens on human health [62]. However, some studies have reported that flavonoids generally have more antioxidant activity than phenolics [70]. On the other hand, the lack of correlation between TFC and ABTS radical scavenging activity is not unexpected, as similar findings have been reported in previous studies on microgreens, particularly those encompassing a wide range of botanical families [71]. In contrast, TFC demonstrated a significant correlation with DPPH radical scavenging activity but not with ABTS, which may be attributed to the variability in specific flavonoid compounds present within different microgreen species. Notably, quercetin exhibited a moderate correlation with ABTS radical scavenging activity, likely due to its relatively higher concentration compared to that of rutin. Moreover, no relationship was observed between the TIA with the other studied traits. However, Tomas et al. [64] reported that tyrosol and their derivatives, quercetin, rutin, and naringenin, exhibited remarkable TIA with both in vivo and in vitro assays. Additionally, the inhibitory effect of the tyrosinase enzyme is likely due to the presence of secondary metabolites, such as phenolics and flavonoids [72]. Overall, the contradictory findings regarding the in vitro antioxidant and TIA may be attributed to the potential synergistic and antagonistic interactions among the various phytochemical compounds present in the microgreens studied. Moreover, other bioactive compounds contributing to the health properties of the microgreens studied cannot be excluded. Confirmatory analysis of these compounds deserves advanced equipment with mass spectrometry in future research.

5. Conclusions

In general, growth performance and bioactive compounds varied significantly between 23 diverse microgreen species. It highlighted the potential diversity in candidate microgreen species with high-yield and bioactive-rich microgreens, including red radish, rat-tailed radish, and Chinese kale. These microgreens are excellent dietary sources of bioactive compounds, and their consumption may have functional implications and promote health benefits. Since microgreens are consumed as fresh produce, factors such as consumer acceptability, perception, and microbiological safety are essential considerations. These aspects will be further investigated in future studies focusing on selected superior species.