About the residual chlorine on fresh cut or ready to eat vegetables

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.

Doesn't anybody know about this? I am waiting for the answers, thanks

Hi Eric, you need to have a bit of patience as most people in Europe are just coming into work and those in North America are still in bed. I'm sure you will get an answer in due course.

oh,sorry,I neglect the time difference.If you don't have the standards or Detection methods ,I think any information about residual chlorine on fresh -cut or ready to eat vegetables is usefull for me.

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

Dear bigkev,

Thanks for your comments, less sure regarding yr appended website.

Any absolute microbial count benefit will clearly depend on the starting bacteriological condition. I believe the typical best results quoted in the literature for “non-high-tech” “disinfection” treatments are a reduction of approx 2 log which from memory equates to 99% . As far as I can see from published data, the individual case-by-case results may well be almost anything up to that level depending on the situation.

There seems to be some tendency in EC to now ban such disinfection treatments altogether for reasons such as you mention.

There also seems to be a consensus that this concept / methodology is simply inadequate to cope with low-level pathogenic contamination although zero tolerance is admittedly not the easiest of compliance requirements.

Hopefully, increased usage of GAP-type schemes will continue to improve the safety prior to harvesting. This issue seems to have been regarded as a (the?) major factor in the (particularly US, documentation-wise) calamities over last 5-10 years.

Rgds / Charles.C