BACKGROUND: The effect of ultraviolet-B (UV-B) light as a postharvest treatment to enhance the antioxidant content of carrots and fresh-cut carrot products was evaluated. Four levels of UV-B dose ranging from 1.3 to 12 kJ m⁻² were applied to whole, baby and various styles of cut carrots, and the changes in antioxidant capacity, total soluble phenolics and phenylalanine ammonia-lyase (PAL, EC 4.3.1.24) activity were measured after a 3 day incubation period at 15 °C and 45% relative humidity. RESULTS: Both cutting style and dose level were factors in determining carrot responses to UV-B treatment. Antioxidant capacity increased significantly (1.4-6.6-fold). Total soluble phenolic results correlated directly with those of antioxidant capacity (R² = 0.953), indicating that the enhancements achieved were due to an increase in phenolic content. High-performance liquid chromatography analysis revealed that 5-O-caffeoylquinic acid (5-CQA) was the primary phenolic responsible for this increase. Higher PAL activity was also observed in UV-B-treated samples, indicating that the increase in 5-CQA was a biological response to UV-B exposure. CONCLUSION: UV-B treatment has the potential to increase the nutritional value of carrots and offers an exciting opportunity to increase consumer accessibility to dietary choices that are rich in antioxidants. Published 2012 by John Wiley & Sons, Ltd.
BACKGROUND: The effect of ultraviolet-B (UV-B) light as a postharvest treatment to enhance the antioxidant content of carrots and fresh-cut carrot products was evaluated. Four levels of UV-B dose ranging from 1.3 to 12 kJ m⁻² were applied to whole, baby and various styles of cut carrots, and the changes in antioxidant capacity, total soluble phenolics and phenylalanine ammonia-lyase (PAL, EC 4.3.1.24) activity were measured after a 3 day incubation period at 15 °C and 45% relative humidity. RESULTS: Both cutting style and dose level were factors in determining carrot responses to UV-B treatment. Antioxidant capacity increased significantly (1.4-6.6-fold). Total soluble phenolic results correlated directly with those of antioxidant capacity (R² = 0.953), indicating that the enhancements achieved were due to an increase in phenolic content. High-performance liquid chromatography analysis revealed that 5-O-caffeoylquinic acid (5-CQA) was the primary phenolic responsible for this increase. Higher PAL activity was also observed in UV-B-treated samples, indicating that the increase in 5-CQA was a biological response to UV-B exposure. CONCLUSION: UV-B treatment has the potential to increase the nutritional value of carrots and offers an exciting opportunity to increase consumer accessibility to dietary choices that are rich in antioxidants. Published 2012 by John Wiley & Sons, Ltd.