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Development of a Continuous Water Recycling Unit for Application in Postharvest Washing of Leafy Greens

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Title: Development of a Continuous Water Recycling Unit for Application in Postharvest Washing of Leafy Greens
Author: Liang, Chen
Department: Department of Food Science
Program: Food Science
Advisor: Warriner, Keith
Abstract: The post-harvest wash process in vegetable processing remains a key intervention step whereby field-acquired contamination can be reduced. In the following thesis, the dynamics of wash water quality within commercial processing lines were assessed for turbidity, conductivity, TSS (total suspended solid), TS (total solid)/VS (volatile solid), pH, ORP and temperature over a typical 6-8 h processing activity. It was found that the organic content of the water progressively increased over the processing period and resulted in the sequestration of sanitizer leading to high microbial levels. In an attempt to reduce the accumulation of organics within the wash tanks, a water recycling system was developed based on an initial coagulation step followed by filtration and final UV disinfection tertiary treatment. Each step in the recycling process was optimized within the laboratory, while the pilot-scale unit was evaluated within a commercial processing facility. From a comparative study it was found that coagulating agents based on chitosan supported a 79% turbidity removal that was comparable to sodium aluminate (86% removal turbidity). Chitosan has the advantage of being non-toxic. In commercial practice the recycling unit could reduce the organic loading of wash tanks and support a two log cfu reduction in microbial loading. The technology holds promise for cost effective continuous water treatment systems within the fresh produce sector.
URI: http://hdl.handle.net/10214/7618
Date: 2013-11
Rights: Attribution-NonCommercial-NoDerivs 2.5 Canada


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Attribution-NonCommercial-NoDerivs 2.5 Canada Except where otherwise noted, this item's license is described as Attribution-NonCommercial-NoDerivs 2.5 Canada