Profiles of Postharvest Agricultural Water in Western Massachusetts

Introduction: As produce has been linked with over 45 percent of all foodborne illnesses, it is important to develop methods to minimize the risk of these outbreaks.  Postharvest agricultural water has been shown as a potential vector for cross-contamination.  On farm use of sanitizer can reduce cross contamination, however, organic load strongly influences sanitizer effectiveness.  Organic load, and its interaction with sanitizer is difficult to quantify, and only limited analysis of field conditions exist.  

Purpose:  Previous research determined that physiochemical properties of postharvest wash water affect sanitizer depletion. This research analyzed postharvest agricultural water from 12 locations in field sites within New England to profile the organic load generated during the production of small to medium farms. This provides a platform to help evaluate commercial produce sanitizers.  

Methods: Samples were taken in triplicate from a variety of postharvest produce washing and cooling processes including hydrocoolers, tumble washers, and dunk tanks, processing with and without sanitizer. These samples were analyzed for physiochemical properties including turbidity and Chemical Oxygen Demand (COD), as well as coliform and E. coli loads using a Quanti-tray 2000.  

Results: Different operations resulted in significant variance in organic loads. Coliform counts varied from 34.4 to over 2419 MPN. The turbidity ranged from 2.7 to 708 NTU.  COD ranged from 8 to 112 mg/L.  The COD, turbidity, and coliform levels did not interact in a linear manner.  The highest measurements came from a tumble washer, and the lowest measurements came from a dunk tank in which water was changed often.  

Significance: Organic load significantly affects sanitizer efficiency.  It is imperative to understand the way postharvest processes generate organic load in order to apply sanitizer in a manner which minimizes chances of outbreaks.