Supplemental UV-B Exposure Influences the Biomass and the Content of Bioactive Compounds in Linum usitatissimum L. Sprouts and Microgreens

Abstract

The interest in the pre-harvest ultraviolet-B (UV-B) exposure of crops in indoor cultivation has grown consistently, though very little is known about its influence on the nutraceutical quality of microgreens. Flaxseeds constitute a valuable oilseed species, mostly appreciated for their nutritional properties and the presence of health-promoting compounds. Therefore, although scarcely studied, flaxseed sprouts and microgreens might constitute a high-quality food product to be included in a healthy diet. This study aims to unravel the effects of pre-harvest ultraviolet-B irradiation on the nutritional and nutraceutical quality of flaxseed sprouts and microgreens grown under artificial conditions. The UV-B irradiation decreased the biomass and stem length of microgreens. However, the content of total phenolics and flavonoids and the antioxidant capacity were strongly enhanced by the UV-B treatment in both sprouts and microgreens. Among photosynthetic pigments, chlorophyll a, violaxanthin, antheraxanthin, and lutein in sprouts were reduced by the treatment, while chlorophyll b increased in microgreens. In conclusion, our results showed that growing flaxseed sprouts and microgreens in controlled conditions with supplemental UV-B exposure might increase their nutritional and nutraceutical quality, as well as their antioxidant capacity, making them high-quality functional foods.

Do changes in Lactuca sativa metabolic performance, induced by mycorrhizal symbionts and leaf UV-B irradiation, play a role towards tolerance to a polyphagous insect pest?

“…Similar to Tsormpatsidis et al ( 2008 ), other studies reported a reduction in fresh and/or dry weight in UV-exposed lettuce (16–18 μmol m −2 s −2 ), although they used different lettuce cultivars (Diaz et al 2006 ). UV-B irradiation negatively affected plant growth also in other plants of food interest, such as basil (18.7 kJ m −2 h −1 ), potato (10 kJ m −2 d −1 ), flaxseed 1.33 (W m −2 ), radish 7.2 (kJ m −2 d −1 ), rice (15.7 kJ m −2 ), barley (0.60–2.30 W m −2 ), bean (0.60–2.30 W m −2 ), and others (Chen et al 2020 ; Dou et al 2019 ; Santin et al 2022 ; Singh et al 2011 ; Teramura et al 1991 ; Tevini et al 1981 ). UV-B-related reduction in plant growth might be due to impairments in the cell cycle caused by DNA photo dimers (Biever et al 2014 ; Yadav et al 2020 ), and the likely damages to the photosynthetic apparatus and the consequent photosynthetic processes (Cuzzuol et al 2020 ; Kosobryukhov et al 2020 ; Piccini et al 2020 ).…”

“…The potential of UV-B radiation and/or the use of AMF inocula to enhance the nutraceutical value of agricultural plants by increasing the content of health-promoting secondary metabolites has been investigated in several species, such as flaxseed (Santin et al 2022 ), basil (Mosadegh et al 2018 ; Nascimento et al 2020 , Battini et al 2016 ), broccoli (Mewis et al 2012 ; Moreira-Rodríguez et al 2017a , 2017b ), wheat (Chen et al 2020 ), rice (Faseela and Puthur 2018 ), lettuce (Baslam et al 2013 ; Avio et al 2017 ), and others (Santin et al 2021a , 2021b ; Avio et al 2018 ; Agnolucci et al 2020 ). However, many studies are conducted using UV-B lamps as a light source (Assumpção et al 2019 ; Aksakal et al 2017 ; Basahi et al 2014 ; Esringu et al 2016 ; Lee et al 2021 ; Park et al 2007 ; Rajabbeigi et al 2013 ; Rodriguez et al 2014 ; Zhang et al 2019 ), but research employing UV-B LEDs is scanty.…”

Microgreens—A Comprehensive Review of Bioactive Molecules and Health Benefits

“…Light is a substantial parameter that greatly affects microgreens production. Light is directly involved in the microgreen yield and nutritional composition, and its variations may affect the quality of microgreens at a greater level [ 63 ]. Brazaityte et al, in 2015, investigated the effect of solid-state LED light over carotenoid content in Brassicaceae species microgreens [ 64 ].…”

“…They found that the lowest irradiance level (110 μmol/m 2 /s) accumulated a lower amount of carotenoids, and the highest irradiance level (545 μmol/m 2 /s) also accumulated a lower amount of carotenoids in mustard and red pak choi by an approximate level of 24% [ 64 ]. Likewise, the spectral component of green color irradiation for the microgreens growth has a positive note in carotene content, whereas the orange spectral light had a negative effect on the carotene content of the microgreens [ 63 , 64 ]. Similarly, the effects of different dosages of blue light and their effects on the concentration of phytochemical compounds, such as carotenes, violaxanthin, zeaxanthin, lutein, chlorophyll, carotenoids, and tocopherols, were also evaluated [ 65 ].…”

Molecular Shield for Protection of Buckwheat Plants from UV-B Radiation

“…In plants, the growth is decreased with the intensity of UV irradiation. UV treatment effectively activates the expressions of secondary-metabolite biosynthetic genes, and also in Linum , canola, soybeans, and other plants, depending on the UV-irradiation intensity and time of impact [ 47 , 48 , 49 ]. UV-B exposure may increase the nutritional and nutraceutical quality of crop plants [ 47 ].…”