title: Ultraviolet-B light treatment increases antioxidant capacity of carrot products.
abstract: 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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Biological and Agricultural Engineering, University of California, Davis, Davis, CA 95616, USA.
authors.forename: Roberto J
authors.initials: RJ
authors.lastname: Avena-Bustillos
authors.forename: Wen-Xian
authors.initials: WX
authors.lastname: Du
authors.forename: Rachelle
authors.initials: R
authors.lastname: Woods
authors.forename: Donald
authors.initials: D
authors.lastname: Olson
authors.forename: Andrew P
authors.initials: AP
authors.lastname: Breksa
authors.forename: Tara H
authors.initials: TH
authors.lastname: McHugh
mesh_terms: D000975:Antioxidants / Q000032:analysis* / Q000737:chemistry; D002726:Chlorogenic Acid / Q000031:analogs & derivatives / Q000032:analysis / Q000737:chemistry; D002851:Chromatography, High Pressure Liquid; D018552:Daucus carota / Q000737:chemistry* / Q000201:enzymology / Q000528:radiation effects*; D004307:Dose-Response Relationship, Radiation; D005511:Food Handling; D005514:Food Irradiation; D018857:Food Packaging; D010636:Phenols / Q000032:analysis / Q000737:chemistry; D010650:Phenylalanine Ammonia-Lyase / Q000378:metabolism; D010940:Plant Proteins / Q000378:metabolism; D018517:Plant Roots / Q000737:chemistry* / Q000201:enzymology / Q000528:radiation effects*; D011801:Quinic Acid / Q000031:analogs & derivatives / Q000032:analysis / Q000737:chemistry; D012995:Solubility; D013997:Time Factors; D014466:Ultraviolet Rays
chemical_list: D000975:Antioxidants; D002726:Chlorogenic Acid; D010636:Phenols; D010650:Phenylalanine Ammonia-Lyase; D010940:Plant Proteins; D011801:Quinic Acid; C473200:5-caffeoylquinic acid