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Keywords:

  • Chemical reactions (organic);
  • fruits/vegetables;
  • GC/MS;
  • phenols;
  • proteins

Summary

This study examined the effect of pH of chlorine-based sanitisers on the reaction of free chlorine with compounds present in a variety of food environments. A model food system was first used to determine chlorine reactions with individual organic compounds. Different classes of organic compounds were added to chlorinated water at three different pHs (2.5, 6.0 and 9.3). Free and total chlorine concentrations were recorded in each sample by titrimetric assay. The results show that the level of free chlorine loss is both organic species dependent and pH dependent. Wash water from six different food sources was added to chlorinated water at three different pHs. The peptone plus catechol model appeared to be the best general predictor of free chlorine loss across all the treatments. GC-MS analysis of samples with resorcinol added indicated that chloroform is produced as a primary trihalomethane product at higher pH values. The findings of this study indicate that solution pH, along with types of organic compound, plays a significant role on free chlorine loss, and chlorine loss can be predicted by the protein and phenolic content of the wash solution.