Monitoring and control of wash water sanitation
Washing is one of the most critical steps in fresh-cut processing that can affect product safety. Wash water must be treated with a sanitizer to prevent cross-contamination. Sanitizer concentration must be monitored and controlled throughout established operational limits, and the residual level must be frequently adjusted with the adequate test method for the correct safety management. When the concentration is not correctly maintained during the washing operation, a high risk of cross-contamination can occur. Different physicochemical parameters measured in the wash water, such as residual sanitizer concentration, pH, redox potential, organic matter content and absorbance at 254 nm have been proposed as tools to monitor and control sanitization. However, the concentration of residual sanitizer in the wash water is the most critical control factor to measure for the precise control of wash water sanitation and in the case of chlorine, also the pH. In our study, we compared different commercial sensors and test methods for measuring chlorine in water before and after washing cut lettuce, shredded cabbage, and diced onion. The concentration of PAA was measured in wash water from washing apples, tomatoes, peppers, and lemons and the possible interferences with the organic matter were examined. Free chlorine was measured with different commercial sensors and test methods, including reflectometric, chronoamperometric, photometric, spectrophotometric as well as amperometric titration and an in line amperometric probe. For PAA, reflectometric, chronoamperometric, drop titration and amperometric probe were compared with the HPLC-DAD analysis as a reference methodology. Results showed that organic matter affected the precise measurement of the sanitizers directly and made it difficult the control of the sanitation process. For chlorine, the amperometric probe did not measure correctly any of the wash water examined due to the interferences with the organic matter released from cutting. For PAA, the organic matter released from lemons interfered with the amperometric probe for measuring PAA.
Albolafio, S., Tudela, J.A., Hernández, N., Sosa, B.P., Allende, A. and Gil, M.I. (2021). Monitoring and control of wash water sanitation. Acta Hortic. 1319, 75-80
chlorine, peroxyacetic acid, water disinfection, sanitizers, sensors