The 2011 ASHS Annual Conference

Chlorine is widely used as a sanitizer during fresh-cut wash operations. However, the large amount of organic materials in the exudates released by cutting depletes free chlorine rapidly, resulting in the potential for pathogen survival and cross-contamination. In this study, a rinsing step installed between cutting and washing, without incurring additional water usage, was tested for its effect on organic load reduction, retention of water quality and sanitizer efficacy in the fresh-cut produce wash system. Batches of 2-lb lettuce shreds were placed on a perforated conveyor belt and rinsed with chlorine water. The samples were collected and the volume of water used for rinsing was determined. The collected lettuce samples after rinse were further de-watered, and washed for 30 seconds in 40 L of chlorinated water containing 35 ppm free chlorine. The changes in water quality after each wash were evaluated in terms of turbidity, chemical oxygen demand, and free chlorine. This process was repeated until the wash water free chlorine level declined to near 0.5 ppm. The same volume of Clorox (6%) that initially brought the chlorine level to 35 ppm was added into the wash water again. The same procedure was repeated two more times. For the control, the lettuce shreds were washed directly in 40 L of chlorinated water without the rinse step; however a volume of chlorine water equal to that used for rinsing was added to the wash basin prior to each wash so that an equal total volume of water was used for each treatment. The results showed that the treatment with rinsing between cutting and washing significantly reduced water quality deterioration as shown in much slower increase in COD and turbidity, and decrease in free chlorine in comparison to the control. This outcome is important for the fresh-cut produce industry, as it demonstrates that a rinse step between cutting and washing can cost-effectively reduce water quality decline and stabilize sanitizer concentration during fresh-cut wash operations.