title: Impact of ultraviolet radiation treatments on the physicochemical properties, antioxidants, enzyme activity and microbial load in freshly prepared hand pressed strawberry juice.
abstract: Freshly prepared, hand-pressed strawberry fruit juice was exposed to ultraviolet radiation (254 nm) at room temperature (25 ℃ ± 1 ℃) for 15, 30 and 60 min with 0 min serving as control. Results revealed decrease in pH, total soluble solids and titratable acidity, while colour parameters (L*, a* and b* values) and clarity of juice (% transmittance) increased significantly. All the results corresponded to exposure time to ultraviolet radiation. Bioactive compounds (total phenolics, ascorbic acid and anthocyanins) decreased along with a recorded reduction in polyphenol oxidase enzyme and 1,1-diphenyl-2-picryl hydrazyl radical scavenging activities, which were again dependent on exposure time. Results on the microbial studies showed significant reduction by 2-log cycles in aerobic plate count as well as in total yeast and mould counts. Though negative results were observed for certain parameters, this is the first time it was endeavoured to demonstrate the impact of ultraviolet radiation radiation on freshly prepared, hand-pressed strawberries juice.
authors.affiliation: Food Technology Division, School of Industrial Technology, Universiti Sains Malaysia, Penang, Malaysia rajeevbhat@usm.my rajeevbhat1304@gmail.com.
authors.forename: Rajeev
authors.initials: R
authors.lastname: Bhat
authors.affiliation: Institut für Landtechnik, Universität Bonn, Sektion Haushaltstechnik, Bonn, Germany.
authors.forename: Rainer
authors.initials: R
authors.lastname: Stamminger
mesh_terms: D000872:Anthocyanins / Q000737:chemistry; D000975:Antioxidants / Q000737:chemistry / Q000528:radiation effects*; D001205:Ascorbic Acid / Q000737:chemistry; D001628:Beverages / Q000032:analysis* / Q000382:microbiology / Q000528:radiation effects; D001713:Biphenyl Compounds; D004156:Catechol Oxidase / Q000737:chemistry / Q000378:metabolism; D005504:Food Analysis; D005516:Food Microbiology; D005519:Food Preservation; D031985:Fragaria / Q000737:chemistry* / Q000201:enzymology / Q000382:microbiology; D010636:Phenols / Q000737:chemistry; D010851:Picrates; D014466:Ultraviolet Rays
chemical_list: D000872:Anthocyanins; D000975:Antioxidants; D001713:Biphenyl Compounds; D010636:Phenols; D010851:Picrates; C004931:1,1-diphenyl-2-picrylhydrazyl; D004156:Catechol Oxidase; D001205:Ascorbic Acid
keywords: Ultraviolet radiation; bioactive compounds; microorganisms; non-thermal processing; strawberry fruit juice