Nutrient Supplementation Configures the Bioactive Profile and Production Characteristics of Three Brassica L. Microgreens Species Grown in Peat-Based Media

Abstract

Brassica microgreens are a fresh microscale vegetable crop of high antioxidant value and naturally dense in nutrients without the intervention of biofortification or genetic engineering. A climate chamber experiment on peat-based substrate was set up to test microgreens growth and accumulation of secondary metabolites in response to nutrient supplementation. Microgreens mineral content was analyzed through ion chromatography and total ascorbic acid through UV-Vis spectrophotometry, while carotenoids and phenolic acids were quantified by HPLC-DAD and UHPLC-HRMS, respectively. Brussels sprouts and cabbage yield was only reduced by 10%, while nitrate was reduced by 99% in the absence of nutrient supplementation. Rocket yield was prominently reduced by 47%, with a corresponding nitrate reduction of 118%. Brussels sprouts secondary metabolites were not improved by the absence of nutrient supplementation, whereas cabbage microgreens demonstrated a 30% increase in total ascorbic acid and a 12% increase in total anthocyanins. As for rocket, the absence of nutrient supplementation elicited an extensive increase in secondary metabolites, such as lutein (110%), β-carotene (30%), total ascorbic acid (58%) and total anthocyanins (20%), but caused a decrease in total phenolic acids. It is hereby demonstrated that growing microgreens on a commercial peat-based substrate without nutrient supplementation can be feasible for certain species. Moreover, it might elicit a species-dependent spike in bioactive secondary metabolites.

Sprouts and Microgreens—Novel Food Sources for Healthy Diets

“…gemmifera) and cabbage (B. oleracea var. capitata) microgreens without nutrient supplementation led to a 99% decrease in the nitrate content while maintaining steady calorimetric qualities and total phenolic acid contents with only minor yield reduction [110]. Under nutrient deprivation, cabbage microgreens even showed a 30% increase in total ascorbic acid and a 12% increase in total anthocyanins.…”

“…Nutrient deprivation in wild rocket (Diplotaxis tenuifolia) microgreen production elicited a substantial increase in secondary metabolites, such as lutein (110%), β-carotene (30%), total ascorbic acid (58%), and total anthocyanins (20%); however, with a concomitant significant yield reduction of 47% [110]. On the other hand, moderate nutrient stress (half-strength nutrient solution-NS) applied to red Salanova butterhead lettuce (Lactuca sativa var.…”

“…For the above reasons, mild salinity, unbalanced mineral nutrition, or complete nutrient deprivation in the growth solution of soil-less culture systems for microscale vegetable production may prove helpful to naturally modulate the levels of functional compounds, such as ascorbate, carotenoids, and phenols. Moreover, it may also curtail anti-nutrients such as nitrate [110].…”

Pearl Grey Shading Net Boosts the Accumulation of Total Carotenoids and Phenolic Compounds That Accentuate the Antioxidant Activity of Processing Tomato

“…Polyphenols profile detection and quantification were performed according to the protocol described in detail by El-Nakhel et al [ 32 ]. Briefly, 5 μL of the extracted samples according to the procedure described by Vallverdú-Queralt et al [ 33 ], were analyzed using a Dionex Ultimate 3000 ultra-high-pressure liquid chromatography (UHPLC) system (Thermo Fisher Scientific TM , Waltham, MA, USA) coupled to an Orbitrap high resolution mass spectrometry (HRMS) (Thermo Fisher Scientific TM , Waltham, MA, USA).…”

Sprouts, Microgreens and Edible Flowers as Novel Functional Foods

“…Concerning the implications of mineral nutrition on the productive characteristics and bioactive profile of microgreens El Nakhel et al [12] and Keutgen et al [13] shed light on the importance of this preharvest factor (i.e., mineral nutrition) on novel microgreens species from the Brassicaceae botanical family. El Nakhel et al [12] demonstrated that growing microgreens species such as Brussels sprouts and cabbage without fertilization application (only osmotic water was used during the whole cultivation cycle) can be feasible (10% of yield reduction accompanied with an 99% reduction of nitrate compared to nutrient supplementation treatment). In the same study, the absence of nutrient supplementation in microgreens rocket exhibited a significant increase in a wide range of metabolites such as β-carotene, lutein, and ascorbic acid but manifested a major 47% decrease in fresh yield.…”