title: Impact of shortwave ultraviolet (UV-C) radiation on the antioxidant activity of thyme (Thymus vulgaris L.).
abstract: Thyme is a good source of antioxidant compounds but it can be contaminated by microorganisms. An experimental fluid bed ultraviolet (UV) reactor was designed for microbial decontamination of thyme samples and the effect of shortwave ultraviolet light (UV-C) radiation on antioxidant properties of thyme was studied. Samples were exposed to UV-C radiation for 16 or 64 min. UV-C treatment led to 1.04 and 1.38 log CFU/g reduction of total aerobic mesophilic bacteria (TAMB) counts. Hunter a(∗) value was the most sensitive colour parameter during UV-C treatment. 2,2-Diphenyl-1-picrylhydrazyl (DPPH) scavenging activity of extracts was not significantly affected by UV-C. Addition of thyme extracts at 0.15 and 0.3 μmol GAE/ml emulsion delayed the formation of lipid hydroperoxides and headspace hexanal in the 5.0%(wt) corn oil-in-water emulsion from 4 to 9 and 14 days, respectively. No significant changes in oxidation rates were observed between UV-C treated and untreated samples at same concentrations.
authors.affiliation: Department of Food Engineering, Faculty of Chemical and Metallurgical Engineering, Istanbul Technical University, Ayazaga Campus, Maslak, 34469 Istanbul, Turkey; Department of Food Science, University of Massachusetts, Amherst, MA 01003, United States.
authors.forename: Esra
authors.initials: E
authors.lastname: Dogu-Baykut
authors.affiliation: Department of Food Engineering, Faculty of Chemical and Metallurgical Engineering, Istanbul Technical University, Ayazaga Campus, Maslak, 34469 Istanbul, Turkey.
authors.forename: Gurbuz
authors.initials: G
authors.lastname: Gunes
authors.affiliation: Department of Food Science, University of Massachusetts, Amherst, MA 01003, United States. Electronic address: edecker@foodsci.umass.edu.
authors.forename: Eric Andrew
authors.initials: EA
authors.lastname: Decker
mesh_terms: D000975:Antioxidants; D010084:Oxidation-Reduction; D000078702:Radiofrequency Therapy; D046930:Thymus Plant / Q000737:chemistry*; D014466:Ultraviolet Rays
chemical_list: D000975:Antioxidants
keywords: Antioxidant activity; Corn oil-in-water emulsion; Oxidation; Shortwave ultraviolet; Thyme