The effect of supplemental LED lighting in the range of UV, blue, and red wavelengths at different ratios on the accumulation of phenolic compounds in pak choi and swiss chard
C.-F. Wesslera,b, M. Weilandb,c, S. Einfeldtd, M. Wiesner-Reinholdb, M. Schreinerb, S. Neugarte
Published in:
Food Res. Int., vol. 200, art. 115438, doi:10.1016/j.foodres.2024.115438 (2025).
Abstract:
Phenolic compounds are known for their health-promoting effects on humans. Pak choi (Brassica rapa ssp. chinensis) and Swiss chard (Beta vulgaris subsp. vulgaris) are used here as model plants, as they are eaten raw as baby leaf lettuce and differ in their phenolic compound profile while showing similar morphology. In a greenhouse an artificial light source with UV-B (215 mW m-2), blue (104 μmol m-2 s-1) and red (245 μmol m-2 s-1) LEDs was implemented to increase phenolic compounds during the last days before harvest. Pak choi shows an increase or trend towards an increase in the monoacylated triglycosides of kaempferol and quercetin after 4 days of irradiation for 4 h each. For example kaempferol-3-caffeoyl-sophoroside-7-glucoside was increased at low PAR values in the third run and red-dominated light treatment by up to 120 %. In addition, it was observed that the red variety ‘Amur’ has higher concentrations of quercetin glycosides which were increased often. In swiss chard, on the other hand, there was only a sporadic increase in vitexin glycosides. Despite very different concentrations in some samples, 2″-glucosyl-vitexin and 2″-glucosyl-6″-malonyl-vitexin showed significant increases of up to 350 % in the two chard varieties Lukullus and Rhubarb chard. The results suggest that the exposure time or intensity of UV-B radiation needs to be optimized for each species and has not yet consistently led to an increase but trends in phenolic compounds and in antioxidant activity in this study.
a Institute of Horticultural Production Systems, Leibniz Universität Hannover, Herrenhäuser Straße 2, 30419 Hannover, Germany
b Leibniz Institute of Vegetable and Ornamental Crops e.V., Plant Quality and Food Security, Theodor-Echtermeyer-Weg 1, 14979 Großbeeren, Germany
c Institute for Biology, Experimental Biophysics, Humboldt-Universität zu Berlin, Invalidenstr. 42, 10115 Berlin, Germany
d Ferdinand-Braun-Institut (FBH), Gustav-Kirchhoff-Str. 4, 12489 Berlin, Germany
e Division Quality and Sensory of Plant Products, Georg-August-Universität Göttingen, Carl-Sprengel-Weg 1, 37075 Göttingen, Germany
Keywords:
Ultraviolet-B radiation; Photosynthetically active radiation; Anthocyanins; Betalains; Flavonoid glycosides; Hydroxycinnamic acid esters; Light emitting diodes
© 2024 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
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