In situ quantification of chlorine dioxide gas consumption by fresh produce using UV-visible spectroscopy

The objective of this research was to quantify the chlorine dioxide (ClO₂) gas, a potent sanitizing agent, absorbed by fresh produce in real time during treatment. The information generated allows for understanding how critical variables such as quantity of absorbed ClO₂ gas and rate of ClO₂ gas consumption relate to other performance metrics without requiring post-processing of the produce. Therefore, a new in situ approach to measure the total absorption of ClO₂ gas by fresh produce requiring minimal sample preparation was developed using a system equipped with a UV-vis spectrophotometer. The system can simulate ClO₂ gas treatment at constant and varying concentrations within a package and/or chamber. Strawberries were selected as model fresh produce to assess the system and to evaluate the impact of concentration and time of exposure on total ClO ₂ gas consumption. It was found that strawberries consume ClO ₂ gas rapidly and that longer exposure times (17 and 84 min) for continuous exposure resulted in around 45% ClO₂ absorption whereas shorter exposure times (7 min) consumed less than 20% of the injected ClO ₂ because the latter did not reach steady state ClO₂ consumption prior to completion.