Abstract:

The effects of light quality on nutritional quality and antioxidant properties of alfalfa (Medicago sativa) sprouts
were investigated in comparison with those of darkness. As compared with control and other light quality treatments, blue
light emitting diodes (LEDs) significantly promoted the contents of soluble protein, free amino acids, vitamin C (VC), total
phenolics and total flavonoids, and the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity of alfalfa sprouts.
Moreover, the content of nitrate was significantly decreased under blue LEDs. The yield of fresh sprouts was increased
observably under red LEDs, while white LEDs were suitable for dry matter accumulation in alfalfa sprouts. In addition,
white LEDs significantly promoted the accumulation of carotenoid and nitrate in sprouts. Yellow LEDs were suitable for
the accumulation of quercetin after 6, 8 and 12 days of culture, concomitantly with the highest PAL activity among all the
investigated treatments. The content of quercetin was positively correlated with phenylalanine ammonia-lyase (PAL) activity
under yellow LEDs. These results revealed that blue LEDs were suitable for promoting the nutrient quality of alfalfa sprouts.
Key words: alfalfa; sprouts; growth; nutritional quality; antioxidant