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ARS Home » Northeast Area » Beltsville, Maryland (BARC) » Beltsville Agricultural Research Center » Food Quality Laboratory » Research » Publications at this Location » Publication #313245
Title: Assessment and speciation of chlorine demand in fresh-cut produce wash water

Author
item WANG, SHIHCHI - Johns Hopkins University
item Luo, Yaguang - Sunny
item LI, JIE - Huazhong Agricultural University
item ZHOU, BIN - University Of Maryland
item JACANGELO, JOSEPH - Johns Hopkins University
item SCHWAB, KELLOGG - Johns Hopkins University

Submitted to: Food Control
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/25/2015
Publication Date: 8/29/2015
Citation: Wang, S., Luo, Y., Li, J., Zhou, B., Jacangelo, J., Schwab, K.J. 2015. Assessment and speciation of chlorine demand in fresh-cut produce wash water. Food Control. 60:543-551.

Interpretive Summary: Chlorine is the most common sanitizer used by the produce industry, due to its effectiveness against a wide range of microorganisms and inexpensive availability. However, organic materials released from cut produce react with chlorine rapidly, resulting in depletion of chlorine, and the consequent survival and spread of pathogens. Scientists at USDA-ARS and Johns Hopkins University investigated the major factors that affect the interactions between organic materials and chlorine loss, as well as the chlorination kinetics of the wash water. This study provides critical information to the fresh-cut produce industry to develop improved strategies to maintain a stable chlorine concentration while conserve water usage during commercial produce wash operations.

Technical Abstract: Production of high quality, fresh-cut produce is a key driver for the produce industry. A critical area of concern is the chlorinated wash water used during post-harvest processing in large industrial processing facilities. Predominantly using a batch process, wash water is recycled over 8hr shifts in tanks continuously imputed with harvested leafy greens or other vegetables. Organic input from residual soil and vegetable material creates increasing chlorine demand within this wash water. Previous studies have focused on the correlation between water quality and the potential of microbial cross contamination, with little research focusing on the chemical properties of wash water. This study evaluated the organic input and chlorination kinetics of vegetable wash water. Using a model system, the vegetable juice released per kg of processed produce for shredded romaine lettuce, shredded iceberg lettuce, shredded carrot and baby spinach was 82.1 ml/kg, 94.5 ml/kg, 158 ml/kg, and 2.26 ml/kg respectively. Batch water analysis revealed fast reaction between constituents in wash water and chlorine where, for all four vegetable wash waters, over 50% of chlorine demand over 90 minutes was fulfilled within the first 5 minutes, underscoring the challenge for any water treatment process to reduce chlorine demand once the vegetables are deposited into chlorinated washing basins.