Red Light-Dose or Wavelength-Dependent Photoresponse of Antioxidants in Herb Microgreens

Abstract

The purpose of this study was to evaluate the role of 638-nm and 665-nm LEDs on changes of antioxidants of basil (Ocimum basilicum) and parsley (Petroselinum crispum), and to assess the effect of light quality on antioxidative status. Plants were grown in peat substrate for 19 days (21/17 ±2°C, 16 h). Experiments were performed in (I) a controlled-environment: B455,R638,R665,FR731(control); B455,R*638,R665,FR731; B455,R638,R*665,FR731; R638; R665 (B–blue, R- red, FR–far-red light). PPFD was set from 231 during growth, upto 300 μmol m-2 s-1 during 3-day treatment changing R638 or R665 PPFD level; in (II) greenhouse (November): high-pressure sodium lamps (HPS) (control—300 μmol m−2s−1); and HPS + 638 (HPS generated 90 and red LEDs—210 μmol m−2s−1). In general, under supplemental or increased red 638 nm light, amounts of tested antioxidants were greater in basil, whereas sole 665 nm or sole 638 nm is more favourable for parsley. Increased or supplemental red light significantly increased contents of phenolics, α-tocopherol, ascorbic acid and DPPH• but suppressed accumulation of lutein and β-carotene in basil, whereas an increase of β-carotene and DPPH• was observed in parsley. Hereby, the photoresponse of antioxidant compounds suggests that photoprotective mechanism is stimulated by both light-dose-dependent and wavelength-dependent reactions.

Nutritional characterization and shelf-life of packaged microgreens

“…The microgreens belonging to the Asteraceae family, particularly chicory microgreens, showed the highest contents. These levels were comparable to those reported by other authors, 12,36,53,57 including commercial microgreens, 5 though tenfold higher amounts were reported in a recent paper by Brazaitytė et al 54 The observed levels of lipophilic compounds were compared to those of the corresponding mature vegetables. 38 The microgreens showed higher contents of α-tocopherol compared to mature vegetables.…”

“…The reported data, expressed on a fresh weight basis, are prevalently included in the range of 0.3-0.6 mg gallic acid per g in several microgreen species (amaranth, basil, kale, broccoli, mustard, tatsoi, orach, borage, beet, parsley, pea, red pak choi, kohlrabi, Swiss chard and rocket). 36,37,52,53 In some cases higher phenolic contents were reported, even exceeding 1 mg gallic acid per g FW, for the same microgreen species (basil, beet, pack choi, mustard, tatsoi and parsley). 15,53,54 It is interesting to observe that such high phenolic contents were recorded in experiments dealing with artificial lighting systems, pointing out the importance of lighting conditions for the accumulation of photoprotective phenolics since the early stages of plant development.…”

“…36,37,52,53 In some cases higher phenolic contents were reported, even exceeding 1 mg gallic acid per g FW, for the same microgreen species (basil, beet, pack choi, mustard, tatsoi and parsley). 15,53,54 It is interesting to observe that such high phenolic contents were recorded in experiments dealing with artificial lighting systems, pointing out the importance of lighting conditions for the accumulation of photoprotective phenolics since the early stages of plant development. 55,56 Among the phenolic antioxidants, anthocyanins resulted a significant fraction only in broccoli (BN) microgreens (Fig.…”

“…Fewer data are available on the α-tocopherol content in microgreens. Samuolienė et al 12,53 reported values ranging from 0.5 (in beet) to 852 (in parsley) μg per g FW. Xiao et al 5 reported very high values in commercial microgreens, in the range of 4.9-87.4 g per 100 g FW in 25 different species.…”

The effect of covering material on the yield, quality and chemical composition of greenhouse‐grown tomato fruit

“…29 Similar results to our study regarding tocopherol composition of tomato fruit have been reported by Pék et al 30 who detected significant amounts of -and -tocopherols, without however detecting -tocopherol, as was the case in our study. The effect of light conditions on tocopherol content of vegetables grown in protected environments has been suggested in several reports, especially regarding leafy vegetables such as lettuce 31,32 and greens, 33 since tocopherol biosynthesis is indirectly affected by light stimulus. 34 Therefore, cover materials with different optical properties are expected to affect tocopherol content and composition in tomato fruit, especially for the early harvested clusters.…”