Digestion of organosulfur compounds of two radish microgreen cultivars grown under different light treatments

Abstract

Radishes are rich in health-promoting organosulfur compounds. This study investigated the effects of gastrointestinal digestion (GID) on glucosinolates (GSLs) and isothiocyanates (ITCs) of two radish microgreens cultivars (Raphanus sativus; cv. Daikon, and cv. Red Rambo) grown in a closed vertical system under either White (W) or Red+Blue (R + B) LEDs, combined with varying applications of UV-C radiation (0, 1, or 3 pulses). The individual and combined effects of LEDs and UV-C on GSLs and ITCs were evaluated before and after GID (INFOGEST static in vitro GID model). Relationships between compounds before/after digestion were explored through Structural Equation Modelling (SEM). Both cultivars are good sources of aliphatic GSLs (Daikon: 513.4 +/- 23.1-681.5 +/- 31.9, Red Rambo: 447.5 +/- 38.5-532.0 +/- 20.2 mg 100 g-1) and ITCs (Daikon: 0.9 +/- 0.1-1.8 +/- 0.3, Red Rambo: 1.3 +/- 0.2-5.2 +/- 1.0 mg 100 g-1). LED type was more impactful than UV-C radiation. Generally, R + B LEDs enhanced GSLs due to increasing dehydroerucin in Daikon, while improving ITCs in Red Rambo. Post-digestion, Red Rambo showed markedly higher sulforaphene levels compared to Daikon. Red Rambo's SEM significantly confirmed the conversion of glucoraphenin into sulforaphene and sulforaphane during GID. In Daikon, no significant relationships between compounds before/after GID were found. These findings suggest cultivar-specific metabolic pathways and responses to light, which can be optimized to enhance the accumulation of health-related compounds. The innovative use of SEM provided deeper insights into the metabolic conversions occurring during GID. The abundant sulforaphene levels from Red Rambo highlight this cultivar as an excellent source of this metabolite and its potential health benefits.