Phytochemical profiling of baby leafy greens from different Swiss chard (Beta vulgaris L.) varieties cultivated under indoor conditions

As consumer interest in functional foods increases, so does the demand for nutrient-dense and visually appealing vegetables. Swiss chard (Beta vulgaris subsp. cicla), recognized for its colorful petioles and nutritional richness, stands as a promising candidate. This study aimed to evaluate the phytochemical composition of baby leafy greens from four Swiss chard varieties (white, yellow, pink, and orange) cultivated using a soilless system under semi-controlled indoor conditions. Plants were grown in a walk-in growth chamber equipped with LED lighting. Seeds were sown in vermiculite-filled trays, kept in darkness for four days to induce germination, and irrigated with a 3:1:6 NPK nutrient solution. Seven days after sowing, uniform and healthy seedlings from each variety were transplanted into individual rockwool cubes and cultivated under a 14/10 h light/dark photoperiod, with temperatures ranging from 20 to 25 °C and relative humidity around 60%. After 27 days of growth post-transplantation, baby leafy greens were harvested for phytochemical analysis using high-performance liquid chromatography with diode array detection and electrospray ionization mass spectrometry. In total, up to 11 phenolic compounds, 4 betalains, and 10 saponins were identified among the different varieties. Pink Swiss chard baby greens exhibited the highest phenolic compound content (12.15 mg/g dw). The white variety was the only one in which betalains were detected (1.99 mg/g dw), comprising one betacyanin and three betaxanthins. The yellow variety presented the highest saponin concentrations (911.1 µg/g dw). These findings reveal distinct phytochemical profiles among Swiss chard baby leaf varieties, emphasizing their chemical diversity and supporting their potential as functional foods rich in bioactive compounds.