Microgreens are young and tender leafy vegetables that have gained wider consumer acceptance. This is attributed to their low caloric composition and rich micronutrient and antioxidant composition. The present study investigated the bioactive composition and proximate analysis of fourteen microgreens belonging to Brassicaceae, Fabaceae, Pedaliaceae, Polygonaceae, Convolvulaceae, and Malvaceae. All the microgreens showed low calories (20.22 to 53.43 kcal 100 g⁻¹) and fat (0.15 to 0.66 g 100 g⁻¹), whilst mung bean and lentil microgreens showed considerable amounts of carbohydrate (7.16 g 100 g⁻¹) and protein (6.47 g 100 g⁻¹), respectively. Lentil microgreens had the highest total chlorophyll (112.62 mg 100 g⁻¹) and carotenoid (28.37 mg 100 g⁻¹) contents, whilst buckwheat microgreens showed the highest total phenolic content (268.99 mg GAE 100 g⁻¹) and DPPH• scavenging activity (90.83 mM TEAC g⁻¹). The lentil microgreens also presented high ascorbic acid content (128.70 mg 100 g⁻¹) along with broccoli, Chinese kale, purple radish, and red cabbage microgreens (79.11, 81.33, 82.58, and 89.49 mg 100 g⁻¹, respectively). Anthocyanin content was only detected in purple radish (0.148 mg CGE 100 g⁻¹) and red cabbage (0.246 mg CGE 100 g⁻¹). The results provide basic information and highlight the benefits of utilizing genetic biodiversity to obtain microgreens with the desired nutrients and antioxidants.

Microbial contamination commonly occurs in microgreens due to contaminated seeds. This study investigated the decontamination effects of water wash (control), 5% hydrogen peroxide (H₂O₂), UV-C (36 watts), advanced oxidation process (AOP; H₂O₂ + UV-C), and improved AOP by combination with microbubbles (MBs; H₂O₂ + MBs and H₂O₂ + UV-C + MBs) on microbial loads, seeds’ viability, and physio-biochemical properties of microgreens from corresponding roselle seeds. Results showed that H₂O₂ and AOP, with and without MBs, significantly reduced total aerobic bacteria, coliforms, Escherichia coli (E. coli), and molds and yeast log count in seeds as compared to the control. Improved AOP treatment of H₂O₂ + UV-C + MBs significantly augmented antimicrobial activity against total bacteria and E. coli (not detected,) as compared to control and other treatments due to the formation of the highest hydroxy radicals (5.25 × 10⁻¹³ M). Additionally, H₂O₂ and combined treatments promoted seed germination, improved microbiological quality, total phenolic, flavonoids, and 2,2-diphenyl-1-picrylhydrazyl radical (DPPH^•) activity of the grown microgreens. Ascorbic acid content was induced only in microgreens developed from H₂O₂-treated seeds. Single UV-C treatment was ineffective to inactivate the detected microorganism population in seeds. These findings demonstrated that improved AOP treatment (H₂O₂ + UV-C + MBs) could potentially be used as a new disinfection technology for seed treatment in microgreens production.