Flume and single-pass washing systems for fresh-cut produce processing: Disinfection by-products evaluation

Authors: ZHANG, TIANQL - Georgia Institute Of Technology; LEE, WAN-NING - Georgia Institute Of Technology; Luo, Yaguang - Sunny; HUNAG, CHING-HUA - Georgia Institute Of Technology

Submitted to: Food Control
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/25/2021
Publication Date: 9/27/2021
Citation: Zhang, T., Lee, W., Luo, Y., Hunag, C. 2021. Flume and single-pass washing systems for fresh-cut produce processing: Disinfection by-products evaluation. Food Control. 133:108578. https://doi.org/10.1016/j.foodcont.2021.108578.
DOI: https://doi.org/10.1016/j.foodcont.2021.108578

Interpretive Summary: Free chlorine is widely used during fresh-cut produce washing process for improving food safety. However, its disinfection byproducts (DBPs) also has negative health effect. Research scientists at Georgia Institute of Technology, the produce industry, and USDA-ARS collaboratively evaluated the effect of produce wash system configuration and operation on the formation of DBPs in wash water and washed produce. While large difference in DBPs in the wash water was found between the two wash systems, final DBPs on washed products were comparable and both were below the daily allowable exposure for drinking water standard established by USEPA. Most importantly, consistent application of final portable wash rinse was effective at minimizing the presence of DBPs on washed produce. Findings benefit the fresh-cut produce industry by presenting opportunities for reducing the presence of DBPs in washed produce, and the consumers with safe and nutritious fresh-cut leafy green vegetables.

Technical Abstract: Free chlorine is widely used in fresh-cut produce washing to minimize microbial cross-contamination, but its application can also lead to the formation of harmful disinfection byproducts (DBPs). This study compared DBPs in process water and washed produce during commercial operation. Samples of shredded lettuce and diced cabbages washed in chlorinated water in the traditional double-flume wash and novel immersion-free single-pass wash systems were collected at multiple time points and locations from the processing lines. A comprehensive suite of 33 conventional and emerging DBPs, including 4 trihalomethanes (THMs), 9 haloacetic acids (HAAs), 9 nitrogenous DBPs (N-DBPs), and 11 carbonaceous DBPs (C-DBPs), were investigated. Overall, N-DBPs and HAAs dominated the detected DBPs. Wash water in the flumes contained 7-111 folds higher DBPs compared to that in the single-pass system, with the abundance of DBPs following the order of N-DBPs > HAAs > C-DBPs > THMs. DBPs were detected on washed produce, presenting primarily in the forms of N-DBPs and HAAs followed by C-DBPs and THMs. While higher levels of DBPs were detected in flume-washed produce, the final potable water rinse helped reduce DBPs in these products. The levels of THMs and HAAs detected on washed produce within this study were used to estimate potential exposure via consumption of fresh-cut produce, which were below the daily allowable exposure for drinking water standard established by USEPA. This study is among the first in evaluating the formation of multiple DBP groups in fresh-cut produce wash water and washed produce as impacted by wash system configuration and operations. Results advance the understanding of the formation and removal of DBPs during wash process, and identify additional research needs and opportunities for further reduction in DBPs and food safety improvement.