EFFECTS OF SELENIUM APPLICATION ON PHENOLIC COMPOUNDS AND ANTIOXIDANT CAPACITY IN BROCCOLI MICROGREENS

Broccoli microgreens have received considerable attention due to their high concentration of bioactive compounds, which contribute to their value as functional foods and ingredients for nutraceutical applications¹. One strategy to improve their nutritional value is agronomic biofortification with selenium (Se), which has been widely investigated for its ability to increase selenium concentration and influence bioactive compounds and antioxidant capacity². Therefore, this study aimed to evaluate the impact of various selenium doses on the total phenolic content and antioxidant capacity of broccoli microgreens. The experiment was conducted using a completely randomized design (n=3) with four treatments: 0 (control), 0.1, 1, and 10 mg Se L⁻¹, applied as sodium selenate to phenolic foam (Green-Up®) at the beginning of cultivation. After nine days, the microgreens were harvested, and total phenolic compounds were determined using the Folin-Ciocalteu method, while antioxidant capacity was evaluated using the ABTS, DPPH, and FRAP assays. Results were expressed on a fresh weight basis (FW). The data were subjected to analysis of variance (ANOVA), and means were compared using Tukey’s test at p < 0.05. Results are expressed as mean ± standard error (SE) Selenium application did not affect (p > 0.05) total phenolic compounds, which ranged from 122.56 ± 6.40 to 143.06 ± 10.90 mg GAE 100 g⁻¹ FW. Similarly, selenium application did not affect antioxidant capacity determined by the ABTS and FRAP assays. However, selenium application affected DPPH radical scavenging capacity. The control treatment exhibited the highest value (89.47 ± 3.39 mg Trolox 100g⁻¹ FW), while the 1 and 10 mg Se L⁻¹ treatments showed the lowest values (63.95 ± 4.60 and 62.34 ± 4.18 mg Trolox 100g⁻¹ FW, respectively). The 0.1 mg Se L⁻¹ treatment exhibited an intermediate response (79.03 ± 2.34 mg Trolox 100g⁻¹ FW), which did not differ from the control or the higher selenium doses. Under the conditions of this study, selenium application did not affect total phenolic compounds or antioxidant capacity measured by the ABTS and FRAP assays. However, higher selenium doses reduced DPPH radical scavenging capacity, suggesting that the response to selenium application varied according to the antioxidant assay used. Although selenium concentration in the harvested microgreens has not yet been determined, the results provide insights into the effects of selenium application on phenolic compounds and antioxidant capacity.

Acknowledgments: This study was financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brasil (CAPES) - Finance Code 001; ESALQ/USP