Abstract
Baby-leaf vegetables are a trade name for leafy vegetables sold as leaves with petioles at the seedling stage. Amaranth (Amaranthus tricolor L.) is a nutritious baby-leaf vegetable containing many bioactive compounds. The effects of short-term ultraviolet B (UV-B) treatments on the growth and quality of baby leaf amaranth were studied, including the conditions of a 24-h recovery period after irradiation, and different irradiation intensities (3.0-9.0 W m(-2)), irradiation periods (4-16 h), and cumulative energies (130-170 kJ m(-2)). A recovery period experiment was conducted to observe the changes in the growth and quality of leaves at 0 and 24 h after UV-B irradiation. The results showed that the concentrations of phenolic compounds, flavonoids, anthocyanin, and ascorbic acid in the leaves, as well as the leaf antioxidant capacity increased 24 h after UV-B irradiation. Increases in target compound concentrations and antioxidant capacity without negative growth and appearance effects were observed in leaves irradiated with UV-B at 3, 6, and 9 W m(-2) for irradiation periods of 12 and 16, 8 and 12, and 4 h, respectively. The highest bioactive compound concentration was found in leaves irradiated with UV-B at 6 W m(-2) for 7 h (cumulative energy: 150 kJ m(-2)). It was concluded that UV-B irradiation at 6 W m(-2) with a cumulative energy of 150 kJ m(-2) and a 24 h post-irradiation recovery period could be an appropriate treatment to increase bioactive compounds in baby leaf amaranth without causing appearance abnormalities.
