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 ClO2 gas consumption. It was found that strawberries consume ClO2 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 ClO2 because the latter did not reach steady state ClO2 consumption prior to completion. (C) 2014 Elsevier Ltd. All rights reserved.