A photoperiod including visible spectrum LEDs increased sulforaphane in fresh-cut broccoli

Abstract

The objective was to elucidate if a photoperiod including fluorescent light (14 h) and visible spectrum LEDs (10 h), during night periods, can increase the phytochemical content in fresh-cut broccoli while not affecting other quality attributes. Monochromatic LEDs used were Cool White -CW-, Blue -B-, Green -G-, Red -R-, and Far-Red -FR-, while darkness was used as control. Changes in weight losses, colour, epiphytic microorganisms, and main bioactive compounds (glucosinolates and isothiocyanates) were assessed during 16 days at 5 ºC. Illumination with G and R lights accelerated yellowing of florets after 14 days. Higher weight losses were registered for LEDs treatments regarding darkness while no changes were observed for microbial development among treatments. All studied photoperiods including LEDs enhanced the sulforaphane content regarding darkness, especially after 7 days, reporting CW, B, and FR treatments increases over 40%. However, the glucosinolate content and myrosinase activity were not stimulated by LEDs. In conclusion, a supplementation with CW, B, or FR LEDs during night periods at retail sale seems a strategy to enhance the sulforaphane accumulation in Brassicaceae. Probably, higher and / or other stresses can be applied to increase / activate the synthesis and accumulation of more secondary metabolites.