Hello everyone,I need the standards and Detection methods about the limited value of residual chlorine on fresh -cut or ready to eat vegetables which be disinfected with sodium hypochlorite or chlorine dioxide.Could someone help me?Thank you very much.
Eric,
Chlorination to be effective is usually at levels around 200ppm however if the produce is in poor condition this will have very little effect. Chlorine levels will also be quickly neutralised by high organic levels in you water. Onions are particularly bad at this.
At most you will only see a 99% reduction in micro counts, 99.9% reductions are bordering on miraculous.
One not well known effect of chlorination, is that it forms carcinogenic chlorinated byproducts like trihalomethanes.....in addition it will taint the produce.
Chlorine needs close control over pH to ensure best performance
In contast
Chlorine dioxide is effective at 5ppm and does not form chlorinated byproducts and is less pH dependent. Again 99.9% reduction in microbes is the limit and organics will neutralise it.
DPD test kits which give a pink colour can be used for both. From memory Chlorine Dioxide results must be multiplied by 2.
Best results will require a countercurrent wash followed by a final spray sanitiser rinse. The sanitser rinse treats the produce at the last step and the residual water returns to the flumeway to maintain a bacteriostasis.
Finally you may also wish to consider using Peroxitane (a blend of Hydrogen peroxide and Acetic acid) that contains peracetic acid. This product is not affected by organics and is used by the big salad companies.
hope this helps
Kevin
safe2eat.com.au
