Phenolic content and antioxidant activity of einkorn and emmer sprouts and wheatgrass obtained under different radiation wavelengths

Sprouted seeds represent intriguing ready-to-eat micro-scale vegetables for the healthy food market, since they are tasty and rich in bioactive compounds. However, sprouts have been recently proposed as a source for the extraction and purification of several phytochemicals to be used in food supplementation or pharmaceutics. Recently, there has been an industrialization of sprout production, carried out indoor, often with use of artificial light, which have implications on biomass yield and composition, and on energetic and economic costs. This work investigates the effects of different radiation wavelengths from light emitting diodes (LED) on free and bound phenolics and antioxidant activity of sprouts and wheatgrass of einkorn (Triticum monococcum L. ssp. monococcum) and emmer ([(Triticum turgidum L. spp. dicoccum, (Schrank ex Schübler) Thell.)]). After 3 days of grain incubation in the dark, three light treatments were applied, labelled as BLUE (447 and 470 nm), RED (627 and 655 nm), and SUN (447, 470, 505, 530, 590, 627, 655 nm), for a same total photon flux density (PFD) of 200 μmol m⁻² s⁻¹. Sprouts were harvested at 5 days after sowing (DAS) and wheatgrass at 9 DAS. The effect of light was generally not significant for sprouts, much greater and species-specific for wheatgrass: BLUE in einkorn and RED in emmer generally increased free and total content of polyphenol (PC), tannins (TC), flavonoid (FC) and phenolic acids (PAs). The antioxidant activity was increased by BLUE in einkorn and decreased by RED in both species. BLUE and RED resulted energy saving compared to SUN.