Antioxidants have been proved to significantly reduce the risk of many diseases including cardiovascular disorders and cancer. This study investigated the effect of Light Emitting Diode (LEDs) wavelengths on the biosynthesis of antioxidants in an antioxidant-rich vegetable, red lettuce (Lactuca sativa L.). Different wavelengths of LED included blue (442 nm), green (517 nm), red (630 nm) and white as a control were used as an energy source to power photosynthesis of the lettuce grown in closed hydroponic systems. Harvested at 45 days of cultivation, mature leaves were determined for total phenolic content, antioxidant activity, and mass productivity. The results showed that white LED provided the highest mass yield (55.21 g m-2 day-1), followed by green, blue and red. Blue treatment although did not provide the best growth for the lettuce, it gave the highest antioxidant properties with IC50 of 7.07 mg mL-1 and total phenolic content of 14.02 mg GAE g-1 DW, which was 17% higher than that obtained from the control. This renders the blue light the best treatment in terms of giving the highest total phenolic productivity. These results suggest that the proper light source could enhance health-promoting compounds in red lettuce. Moreover, antioxidant identification is to be further conducted to define a possible antioxidant mechanism.

Comparison of light emitting diodes colors on antioxidant property of red lettuce grown in closed soilless system

2019 Spring National Meeting

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