Impact of pre‐harvest light spectral properties on health‐ and sensory‐related compounds in broccoli florets

BACKGROUND Plants grown at different latitudes experience differences in light spectral composition. Broccoli ( Brassica oleracea L. var italica ) plants were grown in climate‐controlled chambers under supplemental wavelengths (red, far‐red, red + far‐red or blue) from light‐emitting diodes ( LEDs ). The light treatments were combined with two cold climate temperatures (12 and 15 °C) during broccoli head formation to investigate the effects on morphology and content of health‐ and sensory‐related compounds: glucosinolates, flavonols, ascorbic acid and soluble sugars. RESULTS Supplemental far‐red and red + far‐red light led to elongated plants and the lowest total glucosinolate content in broccoli florets. The content of quercetin was highest with supplemental red light. Vitamin C was not significantly affected by the light treatments, but 12 °C gave a higher content than 15 °C. CONCLUSION The effects of supplemental red and far‐red light suggest an involvement of phytochromes in the regulation of glucosinolates and flavonols. A shift in red:far‐red ratio could cause changes in their content besides altering the morphology. The sugar and vitamin C content appears to be unaffected by these light conditions. Supplemental blue light had little effect on plant morphology and content of the health‐ and sensory related compounds. © 2015 Society of Chemical Industry