Validation of UV coiled tube reactor for fresh juices

• Published in: Journal of environmental engineering and science Vol. 6; no. 3; pp. 319 - 328
• Main Authors: Koutchma, Tatiana, Parisi, Brian, Patazca, Eduardo
• Format: Journal Article
• Language: English
• Published: Ottawa, Canada NRC Research Press 01.05.2007
• Subjects: Chemical properties; Dosimeters; Environmental engineering; Escherichia coli; Evaluation; Fruit juices; Methods; Ultraviolet radiation; United States
• ISSN: 1496-256X; 1496-2551; 1496-256X
• DOI: 10.1139/s06-058

The objective of this study was to validate the performance of a coiled ultraviolet (UV) module with 24 lamps for fresh juice pasteurization. Escherichia coli K12 at an inoculation level of 10 6 cfu mL -1 was chosen as a target microorganism for biodosimetry. All tested fruit juices highly absorbed UV light, with absorption coefficients ranging from 11 cm -1 to 78 cm -1 for lillikoi and pineapple juice, respectively. Of the juices examined, pineapple juice appeared to be the worst case scenario in terms of UV absorptivity and high viscosity. A caramel model solution was developed to mimic juice absorption properties and was used for inoculation studies. The 5-log 10 reduction standard under turbulent flow required by the FDA was achievable in Newtonian liquids with absorption coefficient less than 15 cm -1 after one pass. Turbulent flow was not developed in more viscous orange and pineapple juices at the flow rates tested. A biodosimetry technique that utilizes E. coli as a tracer showed no distribution of UV dose in liquids with absorption coefficient lower than 26 cm -1 . The proposed technique may assist in validating the performance of UV reactors and improve efficiency of UV pasteurization. Key words: coiled ultraviolet module, fruit juices, caramel model, E. coli K12, biodosimetry.