Purpose: This study aimed to determine ClO2 and its by-products left on fresh produces after being treated with ClO2gas generated by different systems.
Methods: Cherry tomatoes and fresh-cut Romaine lettuce were exposed to different concentration of ClO2, i.e., 3, 6 and 10 mg ClO2/l, for 15-60 min and 1, 3 and 6 mg ClO2/l for 5-30 min, respectively. The gas was generated by 3 different methods: sachet with dry precursors (z-series, ICA TriNova, Newnan, GA), ClO2 solution (precursor ICA TriNova, Newnan, GA) and gas generator machine (Minidox-M,Clordisys, Lebanon, NJ ). Chlorine dioxide and chlorite (ClO2-) residues were determined by Amperometric titration (4500-ClO2.C), using an automatic titrator (T50 – Mettler Toledo, Columbus, OH).
Results: Residue on fresh cut lettuces increased with increasing treatment concentration and time independent of the delivery systems, but when treated with the gas generated by the machine more residues were found, e.g., at 6mg/l for 15 min; 23.00 ± 2.69 mg ClO2/kg and 14.12 ± 3.74 mg ClO2/kg of ClO2 and ClO2- were recovered, when treated with gas from continuous ClO2 generation machine and sachet respectively. Tomatoes residues were low when treated with the machine or sachets, 0.27 ± 0.22 mg ClO2/kg, but no residue was found when treated gas generated from the solution.
Significance: Each delivery system has a specific delivery profile that will determine the residue on the fresh produce. The difference in residue found on different fresh produce from each delivery system is significantly different. It is important to identify the ClO2 delivery system when considering ClO2 absorption and levels of residues.