A COMPARATIVE STUDY ON THE ANTIOXIDANT PROPERTIES AND PHENOLIC COMPOUNDS OF GERMINATED WHITE MUSTARD (Sinapis alba L.) SEEDS AND MICROGREENS TREATED WITH NANOPARTICLES

Germinated seeds and microgreens represent two distinct stages of the germination process and have been gaining prominence in the food sector due to their high nutritional value and notable bioactive properties. Carbon quantum dots (CQDs) are spherical nanoparticles smaller than 10 nm, characterized by crystalline networks and fluorescence emission. Several studies suggest that the application of CQDs can enhance plant yield, growth, and productivity. This study aimed to evaluate the effect of nanoparticle application on the antioxidant properties and total phenolic content of white germinated mustard (Sinapis alba L.) seeds and microgreens. The CQDs were synthesized using the hydrothermal method (200°C/2 hours). Seeds of white mustard were pre-treated with CQDs (1 μg/mL), with an elemental composition of 69.37% C1s, 23.07% O1s, and 5.29% N1s, during the imbibition stage (12 hours). Sprouts were germinated for 72 hours at 25°C in darkness inside a germination chamber. Microgreens were cultivated on coconut fiber mat substrate in polystyrene trays for 7 days under controlled conditions: initially at 25°C in the dark, followed by exposure to light (23°C). Non-germinated seeds subjected to treatment (soaking with CQDs) were used as control. Antioxidant activities was evaluated using the ABTS, DPPH, and FRAP methods. Total phenolic content (TPC) was quantified and expressed as mg of gallic acid equivalents per gram of sample (mg GAE/g). Germinated mustard seeds and pre-treated with CQDs showed increases of 38% and 12% in antioxidant activity measured by the FRAP (49.12 µmol TE/g) and DPPH (78.21 µmol TE/g), respectively, while those evaluated by ABTS assay (233.64 µmol TE/g) showed no significant difference (p > 0.05) compared to control. Microgreens showed increases of 110% (74.65 µmol TE/g) and 56% (109.61 µmol TE/g) in FRAP and DPPH assays, respectively, and as observed in germinated seeds, the ABTS assay for microgreens (230.32 µmol TE/g) did not showed a significant difference (p > 0.05) compared to treated non-germinated samples. The total phenolic content was 78% higher in sprouts (25.98 mg GAE/g) and 74% higher in microgreens (25.29 mg GAE/g) compared to the control samples. It is also noted that mustard microgreens exhibited higher antioxidant properties in two (FRAP and DPPH) of the three assays evaluated, when compared to germinated seeds. Based on the results obtained, it can be concluded that pre-treatment with carbon quantum dots and the germination process, whether combined or applied separately, have positive effects on the antioxidant properties of white germinated mustard seeds and microgreens.