Table 3 LED employed for enhancement of secondary metabolites and biological activity in fruits and vegetables
LED Light used | Light Intensity | Crops | Secondary metabolites/ biological activity | References |
|---|---|---|---|---|
Blue: 470 nm | Fluence rate 40 Wm− 2 | Immature strawberries | Total phenolic content increased by 13.0% | Kim et al. (2011) |
Blue: 525 nm | At a fluence rate of 20 Wm− 2 | Immature broccoli | Total phenolic content increased by 1.80% | |
Red: 635 nm, Blue: 460 nm Yellow: 585 nm |  | Pea sprouts | Total phenolic content and total flavonoid contents of pea sprouts under blue, red and white fluorescent light were 1.46, 1.25, 1.45 times and 24.55, 21.01, 24.29 times, respectively | Liu et al. (2016) |
Red | 50 μmol m−2 s−1 | Malus domestica Borkh | Anthocyanin production | Lekkham et al. (2016) |
Blue: 460 nm | 133 ± 5 μmol m− 2 s− 1 | Green oak leaf (Lactuca sativa var. crispa) | Chlorophyll content was highest(1.31 mg/g) with red LED plus florescent light | Chen et al. (2014) |
UV-A: 365 nm, UV-B: 311 nm | 300 μW∙cm− 2 | Ziyan leaves (Camellia sinensis L.) | The anthocyanin content was the highest under UV-A treatment (66.0% (107.98 mg/100 g FW) and delphinidin, cyanidin, and pelargonidin contents increased by 64.57, 80.12, and 49.34%, respectively, compared with control | Li et al. (2020) |
Red: 638 and 665 nm | 300 μmol m− 2 s-1 for 16 h | Mustard | Total β- carotene content increased from 0.028–0.073 mg/g. | Brazaityte et al. (2016) |
Blue and white | 20 μmol s− 1 m− 2 | Chinese kale sprouts | Total phenolic content of sprouts increased by 34.55 and 69.09%, respectively under blue and white LEDs | Qian et al. (2016) |
Blue and red | 80 μ mol m− 2 s− 1 | Chinese cabbage and lettuce | Total phenolic content production | |
Red and blue |  | Strawberry Fragaria× ananassa | Highest contents of total anthocyanin was 136 μg·g− 1 and Pelargonidin 3-glucoside 122.18 μg·g− 1 when treated with blue LED. Increased fucoxanthin content (25.5 mg/g) | Zhang et al. (2018) |
Blue:450 nm–470 nm) | – | Panax ginseng | Total ginsenosides increased from 2.0 to 74.0% | Park et al. (2012) |
370 and 385 nm (UV-A LEDs) | 30 W/m− 2 for 5 days | Kale | Total phenolic content at UV-A 370 nm increased by 14.0% | Lee et al. (2019) |
Purple: 380 nm, Blue: 440 nm, Red: 660 nm | 50–80 μmol m− 2 s− 1 | Vitis vinifera | Trans-resveratrol and cis-piceid accumulation were increased with concentrations of 18.2 and 55.7 μg g− 1 FW, respectively in blue and red LED treated leaves | Ahn et al. (2015) |
Blue + Red | 168 μmol m− 2 s− 1 | Carrot (Daucus carota L.) | Phenolic acids and rutin increased by 45.0 and 65.0%,respectively compared to darkness | Castillejo et al. (2021) |
|  | 50–80 μmol m− 2 s− 1 | B. rapa, B. oleracea var. capitata | Vitamin C and polyphenolic content production | Lee et al. (2014) |
Blue:440–450 nm Red:(650–660 nm | 85–150 μmol m− 2 s− 1 | Solanum lycopersicum L., (Mature green tomatoes) | γ - aminobutyric acid (GABA) increased to 797 μg·g − 1 dw treated with blue LED | Dhakal et al. (2014a) |
Green | ~ 200 μmol m− 2 s− 1 | Lactuca sativa, Lens culinaris, Triticum aestivum L., | Phenolic content, vitamin C, tocopherol and anthocyanin production | Bantis et al. (2016) |
Yellow | ~ 100 μmol m− 2 s− 1 | Raphanus sativus, Malus sp., S. lycopersicum, C. annuum | Vitamin C, α and β-tocopherol and lutein production | |
Red and Blue | Red, 45; Blue, 86; RB, 52 μmol/m2 s | Chinese Cabbage (CR Ha Gwang) and Kale | The total polyphenols in ‘CR Ha Gwang’ were increased by red + blue LED by (3.889), Red (3.817), Blue LED (3.776 μg/mL), and in ‘Kale TBC’ by RB (3.738), Red (3.772), Blue (3.772) | Lee et al. (2016) |
(Blue: 430 nm + Red: 660) (Blue+Red+Far-Red: 730 nm) | 173 and 197 μmol m− 2 s− 1 for B + R and B + R + FR, respectively | Carrot (Daucus carota L.) | Both LEDs treatments (B + R and (B + R + FR) increased the phenolic content (phenolic acids and rutin) by 45 and 65%, respectively compared to darkness. | Martinez et al. (2021) |
UVC Radiation | 1.0, 3.0, and 12.2 kJ m− 2 for 1, 3, or 12 h | Light red tomatoes | The lycopene content was found to increased by 14.0% | Hu et al. (2019) |
Blue and Red | 167 lx for 12 h | Radish Sprouts (Raphanus sativus) | Sprouts grown under blue LED light had about 11.0% higher content of phenolic compounds than sprouts grown under red LED light | AbdElgader et al. (2015) |