The objective of the present study was to evaluate the periodical UV-B radiation hormesis during kale seeds germination in their main content of secondary metabolite compounds (phenols; glucosinolates; total antioxidant capacity –TAC–) and their changes during a refrigerated shelf-life. The total UV-B doses received were 0, 5, 10, and 15 kJ m−2 (CTRL, UVB5, UVB10, and UVB15) in where the 25% was applied on the 3rd, 5th, 7th, and 10th sprouting day. UV radiation did not affect the morphological development of the sprouts. UVB10 and UVB15 treatments increased their phenolic content (>30%). Likewise, TAC was increased by UV-B lighting ~10% (DPPH) and ~20% (FRAP). The hydroxycinnamic acid content in UVB15-treated sprouts increased by 52%, while UVB5 reported an increase of 34% in the kaempferol-3,7-di-O-glucoside concentration, compared to CTRL. After 10 d at 4 °C of shelf-life, content of gallic acid hexoside I and gallic acid increased by 55 and 78% compared to UV-untreated kale sprouts, respectively. Glucoraphanin was the main glucosinolate found in kale sprouts and seeds, followed by 4-hydroxy-glucobrassicin, whose biosynthesis was enhanced by UVB10 (~24 and ~27%) and UVB15 (~36 and ~30%), respectively, compared to CTRL. In conclusion, periodical low UV-B illumination represents a useful tool to stimulate phytochemicals biosynthesis in kale sprouts as an important source of bioactive compounds with potential health benefits.Noelia Castillejo was funded by a predoctoral grant (FPU16/04763) from the Spanish Ministry of Education. Lorena Martínez-Zamora's contract (21322/PDGI/19) is part of the Regional Programme for research talent and its employability of the Seneca Foundation, co-financed by the European Social Fund (ESF) through the Youth Employment Initiative (YEI). The technical assistance of Francisca Andreo is highly appreciated
