Characterization and mitigation of chemical oxygen demand and chlorine demand from fresh produce wash water

Authors: TENG, ZI - University Of Maryland; Luo, Yaguang - Sunny; Zhou, Bin; WANG, QI - University Of Maryland; Hapeman, Cathleen

Submitted to: Food Control
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/22/2021
Publication Date: 3/27/2021
Citation: Teng, Z., Luo, Y., Zhou, B., Wang, Q., Hapeman, C.J. 2021. Characterization and mitigation of chemical oxygen demand and chlorine demand from fresh produce wash water. Food Control. 127:1008112. https://doi.org/10.1016/j.foodcont.2021.108112.
DOI: https://doi.org/10.1016/j.foodcont.2021.108112

Interpretive Summary: Washing is essential for ensuring the quality and safety of fresh-cut produce. Water reuse and reconditioning during washing becomes increasingly important due to heavy water usage and water scarcity. This study investigated major classes of chemical compounds released from cut produce that negatively impact water reuse and reconditioning. Results highlight the important roles of sugars, proteins, acids, and phenolics to chemical oxygen demand and chlorine demand, two major properties determining the quality of produce wash water and efficacy of chlorine-based sanitization, respectively. Information is useful to the fresh-cut processors in developing strategies for food sanitization and effective approaches for reconditioning and reuse of produce wash water.

Technical Abstract: Chlorine-aided washing assures quality and safety of fresh-cut produce. Organic exudates from produce elevate chlorine demand (CLD) and chemical oxygen demand (COD) in wash water, thus compromising food sanitization and subsequent water treatment. We herein profile the organics in process water derived from four produce types: romaine lettuce, iceberg lettuce, onions, and carrots. COD contribution ranked as sugars (over 90%) > proteins/peptides > acids > phenolics. CLD from identified compounds depended highly on produce type. Predominant CLD contributor were proteins/peptides for lettuce (~55%) and onions (33%), versus sugars (36%) for carrots. CLD by phenolics and acids ranged from 7-17% and 20-33%, respectively. Finally, while MW-based separation led to greatest CLD reduction in romaine lettuce wash water, ion-exchange proved most effective for three other produce types. This study highlights the variation in water chemistry and quality occurring during produce washing, and it entails prudent, product-discriminative design for sanitization and water treatments.