Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 3/7/2009
Publication Date: 6/6/2009
Citation: Geveke, D., Torres, D.,2009. Pasteurization of Grapefruit Juice using a Centrifugal Ultraviolet Light Device [abstract].Institute of Food Technologists Annual Meeting. Anaheim, CA. p.1. Interpretive Summary:
Technical Abstract: The pharmaceutical industry uses UV devices to nonthermally inactivate viruses in liquids. To overcome the low penetration depth of UV in some liquids, such as serum plasma, thin films are formed by centrifugal force. Liquid foods also have low UV penetration depths. Studies are lacking on nonthermal pasteurization of juices using UV devices that centrifugally form thin films. The objective of this study was to determine the nonthermal inactivation of Escherichia coli in grapefruit juice using a UV device that centrifugally forms a thin film. Grapefruit juice was inoculated with E. coli K12 ATCC 23716 to 7.7 log cfu/ml. The juice was UV processed at the following conditions: UV intensity 1.5 to 7.5 mW/cm2; cylinder rotational speed 450 to 750 RPM, cylinder angle 15 to 45 degrees, temperature 25 C, and flow rate 300 ml/min. Appropriate dilutions of the samples were pour plated with TSA. Sublethal injury was determined using TSA + 3% NaCl. The effect of storing the UV treated cider for 35 d was investigated. Nonthermal UV processing at 6.0 mW/cm2, 450 RPM and 15 degrees reduced E coli in grapefruit juice by 5.1 log. Inactivation increased with increasing UV intensity. The inactivations at 600 and 750 RPM were similar, and were better than at 450 RPM. The results at 30 and 45 degrees were similar, and were better than at 15 degrees. The occurrence of sublethal injury was not detected. Storing UV processed grapefruit juice at 4 and 10 C reduced E coli from 2.6 log cfu/ml to below detectable levels in 14 d. These results suggest that grapefruit juice may be nonthermally pasteurized using a UV device that centrifugally forms a thin film. Such UV devices may be able to pasteurize other liquid foods, and have significance for ensuring food safety while maintaining quality.