40 replies to this topic

[Simon]

I split this question from another topic for Max.

We are washing and disinfecting vegetables by using chlorine (eau de Javel) in powder form. Is there a regulation, law, etc. saying that these products have to be approved for food contact like there is for cleaning products (EC Regulation on biocides)? Which chlorine is it best to use (liquid or powder) in terms of activity against microorganisms?

[mrfoodlaw]

I split this question from another topic for Max.

We are washing and disinfecting vegetables by using chlorine (eau de Javel) in powder form. Is there a regulation, law, etc. saying that these products have to be approved for food contact like there is for cleaning products (EC Regulation on biocides)? Which chlorine is it best to use (liquid or powder) in terms of activity against microorganisms?

I know the situation in the UK at least.

The issue here is residues on the final vegetables

if there are chlorine residues on the veg which exert a preservative effect - not allowed (chlorine not a permitted miscellaneous additive)

If the veg is sufficiently rinsed in potable water and there are residues which exert no technological effect, then permitted, classed as processing aid

[Charles.C]

Dear Simon / Max,
The usual first chemical requirement is one of stated-validated food grade status as defined for example, by Codex. The details will depend on which active chemical is in the powder / liquid, (powder is typically calcium hypochlorite and liquid sodium hypochlorite but there are various possible exceptions- chlorine dioxide for example).
Regarding residues, I have no idea in this super- technical environment. I wonder how you quantify the 'no technological effect' in previous post, analytical test for ppm of residual chlorine perhaps ?
You asked which type is preferable, it depends on the actual chemical again. From a purely functional viewpoint typical calcium hypoclorite powder usually leaves residues of calcium carbonate everywhere whereas the sodium / liquid type is much cleaner but usually weaker in chlorine, eg 60% vs 10% .

Rgds / Charles.C

[Max]

Charles C, mrfoodlaw,

thanks for replying to my question!!

Dear Simon / Max,
The usual first chemical requirement is one of stated-validated food grade status as defined for example, by Codex. The details will depend on which active chemical is in the powder / liquid, (powder is typically calcium hypochlorite and liquid sodium hypochlorite but there are various possible exceptions- chlorine dioxide for example).
Regarding residues, I have no idea in this super- technical environment. I wonder how you quantify the 'no technological effect' in previous post, analytical test for ppm of residual chlorine perhaps ?
You asked which type is preferable, it depends on the actual chemical again. From a purely functional viewpoint typical calcium hypoclorite powder usually leaves residues of calcium carbonate everywhere whereas the sodium / liquid type is much cleaner but usually weaker in chlorine, eg 60% vs 10% .

Currently, we are using chlorine pellets containing sodium dichloroisocyanural (don't know if I translated correctly but should be something like this). Now, to me that name suggest the possibilty that CN as well as Cl residues could be present in the final product if it is not rinced correctly. Please correct me if I'm wrong.
This is why I asked whether there is a regulation on the chlorinating agents themselves...

These pellets are put into water at the beginning of the day in order to disolve them. Then they are used throughout the day. As chlorine is a very volatile product, I think that there can bequite a big difference between products washed early in the morning and those washed later on as there is a constant loss of active chlorine. Furthermore, there always remains a little rest of undisolved powder on the bottom of the "disolving container".

All these facts make me believe that the use of liquid chlorine (containing sodium hypochloride indeed) would be more efficient, yet more dangerous to handle than a powder and more diffcult to keep the right proportion (adding 5 pellets is easyier than adding x ml for example).

Concerning the chlorine concentration of the two products, this is a calculation that will have to be done in order to see which one would be cheaper, but first of all I would like to determine which one is easyier to use and provides a final product with the best quality.

I think that the antimicrobial effect only depends on the active chlorine concentration given by the producer and not on the type of chemical component.

So, my question are:

Is sodium hypochloride safer than sodium dichloroisocyanural for both the product an the person that manipulates it? Or, which one would you preferably use? Are there other products that you would recommend?

[just me]

These pellets are put into water at the beginning of the day in order to disolve them. Then they are used throughout the day. As chlorine is a very volatile product, I think that there can bequite a big difference between products washed early in the morning and those washed later on as there is a constant loss of active chlorine.

Dear Max,

IMO, it may be good to check the chlorine level before and after a batch to ensure that the concentration is still sufficient. I've seen many in the industry use "chlorine strips" to check concentration.

It is highly possible that by the 2nd or 3rd wash, the strength would be greatly diluted.

There are also chlorine tablets for the food industry, 1 tablet to a certain amount of water. Not quite sure the active ingredient though.

Cheers,

[Max]

Dear Max,

IMO, it may be good to check the chlorine level before and after a batch to ensure that the concentration is still sufficient. I've seen many in the industry use "chlorine strips" to check concentration.

Dear just me,

can the concentration of hypochloride be considered as the same as the concentration of chlorine? As far as my knowledge in chemistry goes, hypochloride dissociates to give both, active chlorine and Cl- ions, depending on the pH of the medium (water in this case)...
The testing kit I have, mesures the concentration in Cl-. Now, this could be usefull for checking that there are no chlorine residues left on the final product but I think that this method will not provide information on the efficiency of the wash?!

It is highly possible that by the 2nd or 3rd wash, the strength would be greatly diluted.

There are also chlorine tablets for the food industry, 1 tablet to a certain amount of water. Not quite sure the active ingredient though.

I might not have been very clear on this point. Actually, we do not use the same bath several times but change the water at every wash and add new chlorine. The problem is that the pellets (or tablets might actually be the better word) must be disloved in a small amount of water before putting them in the container used for washing the vegetables, otherwise they will not disolve and stay on the bottom of the container.

But I think that we use these tablets you are talking about, even if they are not "certified for food contact" or for the food industry. Is there something like this written on the packing of the tablets you are talking about?

Regards,
Max

[Charles.C]

Dear Max,

The active ingredient is probably sodium dichloroisocyanurate which has become popular for chlorination in swimming pools over recent years (easy use and effective).
It seems to have also become popular for yr application, try -
http://www.medentech...t_info.cfm?ID=2
and
http://members.aol.c...bio999/food.htm
and
http://www.guest-med...ter_foodsaf.htm

If you want a look at some chemical details can try -
http://www.fao.org/a...ils.html?id=878
or
http://www.cfsan.fda...b/opa-envt.html

I remember evaluating it once as a water disinfectant but the cost was unacceptable for large scale use compared to sodium hypochlorite. This will depend on your options for sod.hypochlorite which if you use it by dilution from the 10% conc. form is extremely unpleasant to handle in my experience. If you have lower dilutions readily available maybe the conclusion is less unpleasant. It will depend how much quantity / strength you are using.
The same provisos will exist on Food Grade requirements in either case. Yr supplier shd have the answers to this.
As noted JustMe, can check level by paper (quick but only approximate) or something like DPD tablets which need a hand-held colorimeter and will require some initial sample dilution although the result is more accurate in my experience.
Rgds / Charles.C

[wayne]

Dear All

Sodium dichloroisocyanurate tablets can be purchased from BOOTs chemist shop; it is commonly used for disinfecting baby's milk bottles.

Calcium hypochloride, in powder form, is more stable than the liquid sodium hypochloride. Free available chlorine is the active species and it is pH dependent. It is sensitive to organic matter; therefore, the targeted object(s) needs to be clean /flashed with clean water prior to treatment. Sodium hypochloride has been used to treat minimally processed vegetable crops. Precaution must be taken as chlorine is very corrosive to metal.

Litmus paper type is a very crude test method; it is commonly used by amateur or we call it 'a swimming pool test kit'. I do agree with Charles C that DPD titration method is a better and more accurate test method with accuracy down to ppm, but the reagent is very toxic.

Kind Regards
Wayne

[Charles.C]

Hi Wayne,
I daresay you are correct about stability however, unless they have come up with an improved version, calcium hypochlorite was also a devil to work with for my storekeeper, everything had to be done in open air same as sodium hypochlorite conc. liquid. (I switched to the liquid for this reason, price and the calcium deposit problems).
I've never worked with the dichlorisocyanurate (don't have a swimming pool or baby) but it appears relatively user friendly?.
I have also tested a US product which was a shelf-stable powder composite of sodium hypochlorite and sodium hypobromite (from memory) which was also wonderful to use (low odour, no dust) but cost a fortune again.
To answer one of Max's original queries, he will note that the available chlorine content of these products varies a lot, this controls the usage amount to generate a certain desired active ppm in solution. Also relates to the cost.
I didn't know about toxicity of DPD, nothing on label I think. Useful knowledge.
Rgds / Charles.C

[wayne]

Dear Charles C

Dichlorisocyanurate is a user friendly compound and is also stable. However, it is expensive, at least with my memory.

With my own experience for on - the- farm situation, a FAC at 150ppm is the magic conc ( cidal conc) for use as a surface disinfectant for vegie crops; anything less will not be effective and it will exert toxicity to the crops at a higher conc. therefore, the sensitivity of a test method deployed in monitoring the conc is extremely important.

Sorry, I have no experience with the US product.

Sodium hypochlorite is extremely unstable; apart from pH, it is also temperature and light sensitive. The neat drum from manufacture(s) is around 13% (from memory- could be 14%, can someone check on this! ). However, the actual concs at receiving point vary from 13% to as low as 9%. Therefore, it is highly essential to check the neat conc before making in-use solutions.

I have no problem with the DPD but the reagent used for titration is toxic (I cann't recall the name of this reagent from memory at this moment but will report back to you when my memory comes back).

Regards
Wayne

[Max]

Dear Charles C

Dichlorisocyanurate is a user friendly compound and is also stable. However, it is expensive, at least with my memory.

Dear Wayne, Charles C.

I think that dichlorisocyanurate is a very user friendly and stable compound as long as it is not disolved... Concerning the price it is also slightly more expensive than hypochloride but the difference is not that important (at least for the product I'm using).

So you would recommend the use dichlorisocyanurate rather than hypochloride? Is that right?

With my own experience for on - the- farm situation, a FAC at 150ppm is the magic conc ( cidal conc) for use as a surface disinfectant for vegie crops;

Indeed we do use a concentratioon of 150 ppm for our vegetables. I think that this is the highst amount you can/should use according to the codex and other documents I found.

The testing kit I am using is based on a complexometric titration using silver nitrate and 1,5 - Diphenylcarbazon. What do you think of that method in comparison to the DPD method?

Does anyone have experience with other cleaning/disinfecting agents (organic acids, ozone, etc.)?

Regards,
Max

[Charles.C]

Dear Max,

Didn't quite understand yr opening comment … 'as long as it's not dissolved' please clarify.
(Is it the deposit you initially mentioned - maybe the filler in the tablet which insoluble in water, or liquid odour or handling problem? - these are also typical dislikes to sodium hypochlorite solution at 150 ppm level).
Personally I am surprised at such a high ppm chlorine level, this level is what is typically used to disinfect process tables. I have not worked with vegetables but I never went over approx 10 ppm for seafood, normally much lower. Why is it so high ? (you say that the basis is referred in Codex ?)
Regarding the choice, the first requirement is to be assured that the product you are using is food safe. This will be product composition specific since there are multiple components in the tablets plus possible heavy metals etc. I guess that as a minimum the item will have been licensed / identified by local health officials as usable for food contact with any related provisos, eg subsequent rinsing whatever. This is firstly your supplier's responsibility. Not trying to be negative but there are so many reasons to be cautious regarding food chemicals.

Assuming the last paragraph is satisfiable and expense is not an issue, sounds like usage of dichloroiso...should be easier compared to sodium hypochlorite method (assuming yr supply of NaOCl is at 10% or more and on the comments at top). Wayne will probably have something to say on routine use of dichloroisocyanurate.
Regarding analysis, it depends what accuracy you need and the kind of variation you are now seeing. If you are referring to stock solution, I would have thought not so much change during 1/2 day for a ,say, 200L covered tank whatever ? I have used paper to monitor in the range 100 - 150 ppm for NaOCl disinfectant, colorimetric using DPD will need accurate dilution down to the range 1 - 5 ppm (not difficult) and then the result is quick / fairly accurate but will always be less accurate than direct titration at levels of 150 ppm. For NaOCl there are many titrations available, for dichloroiso.… no idea. No doubt Wayne knows this one also.

Rgds / Charles.C

[Max]

Dear Max,

Didn't quite understand yr opening comment … 'as long as it's not dissolved' please clarify.

Dear Charles C,

what I mean is that initially, the product we use is solid (tablet) and therefor easier to use, to handle and not as much likely to loose it's effectiveness (active chlorine concentration) as hypochloride which is liquid. Yet, before using these tablets, we have to disolve them in a small amount of water. Reason is that if we don't, the tablets will not disolve entirely in the bath or form a deposite. But the problem is that we do this in little transparent containers (200 ml cups). Now this is not a problem if this solution (water + tablet) is used quickly but if it is not, then there might be some variation in the active chlorine concentration.

This is another point why I would like to change the actual method or product we use to do this chlorination...

Personally I am surprised at such a high ppm chlorine level, this level is what is typically used to disinfect process tables. I have not worked with vegetables but I never went over approx 10 ppm for seafood, normally much lower. Why is it so high ? (you say that the basis is referred in Codex ?)

Maybe you can have a look at this:

http://listproc.ucda.....disinfection"

Here you can see that typically levels of 50-200 ppm are used for fruits and vegetables.

Then you have this document, saying that 100 ppm can be used:
http://www.who.int/f...rface_decon.pdf

GHP guides from the french and luxemburgish government say that concentrations of max. 150 ppm are allowed (sorry no link).

Regarding the choice, the first requirement is to be assured that the product you are using is food safe. This will be product composition specific since there are multiple components in the tablets plus possible heavy metals etc. I guess that as a minimum the item will have been licensed / identified by local health officials as usable for food contact with any related provisos, eg subsequent rinsing whatever. This is firstly your supplier's responsibility. Not trying to be negative but there are so many reasons to be cautious regarding food chemicals.

Actually, this is why I wanted to know whether there is a european regulation or some official document where I can see what the requirements for "food safe " products are. Because if there are no legal requirements, how can a supplier justify that his product actually is food safe. For example, there is a list of biocides which have been tested and approved as being effective against the avian influenza virus:

http://favv.belbone....ppe-aviaire.pdf

So, this is a list with product & producer names as well as an offial agreement number. Does something like this exist for products that can be in contact with food? To my knowledge, such a list does not exist in Luxembourg...

Regards,
Max

[Charles.C]

Dear Max,
Thks yr links. I also had a quick browse regarding 'chlorine' application and I agree that there seems to be a routine acceptance to use hypochlorite based items in the range 50-150ppm. I failed to find any specific Codex guideline for vegetable processsing with numbers attached but I daresay it's there somewhere.
I noticed the summary of yr second link contained -
'Vigorously washing fruits and vegetables with safe water reduces the number of microorganisms by 10-100-fold and is often as effective as treatment with 200 ppm chlorine.' Interestingly, I have seen similar words used for seafood in the past.
.
One thing that surprised me was that that most of the refs seemed to depend on quite old data (pre 2000). People have become rather more sensitive with respect to residues these days. I found this link detailing the procedure whereby one of the other newer chemicals for this type of application was approved. May be interesting to you.

http://www.foodstand...les/A393_FA.pdf.

Regarding stability of your dicloroiso … product, this ref. has some info. under the sanitisers section (and also at the end) -
http://www.sardi.sa....news/pack54.htm

The usage data looks quite encouraging to me though it is for citrus application (and the brand included fillers may differ). Note the comment about checking that compound usage is accepted in country of destination (?). One simple way to satisfy yourself on strength variation is to test ppm Cl2 over time. My guess is that it is not too bad.

Yr last link is exactly what I was referring to with respect to the role of the local / national public health (usually anyway) but it can be done in various ways. Some countries (US / Canada I believe) have an encyclopaedia of all approved brands / chemicals / applications so that if it's not there, you have to question. Other countries maintain a list such that the distributor cannot legally sell the product if no number (particularly if it is imported (?)). Codex also maintains a so-called Food Codex volume but I'm not sure how comprehensive this is. This kind of check is fundamental to a HACCP system. As I said earlier, this should firstly be yr suppliers problem but I agree it is not always easy to extract the information, particularly if it's a sub-supplier. The point is that working with no info. includes the problem to you.

Rgds / Charles.C

[Max]

I noticed the summary of yr second link contained -
"Vigorously washing fruits and vegetables with safe water reduces the number of microorganisms by 10-100-fold and is often as effective as treatment with 200 ppm chlorine." Interestingly, I have seen similar words used for seafood in the past.

Dear Charles C,

I think that the use of chlorine is not necessary as long as your equiepement allows you to keep the washing water clean. Yet, our machine is quite old and the salad is being washed for about 15min in the same water without any fresh water coming in. So, if there is mo water sanitizing agent present, then will the salad not be recontaminated by the bacteria in the water? So I think that the use of chlorine actually helps preventing recontamination of the product by keeping the water clean and in that way, the washing time can be increased.

What we actually do, in order to improve the efficiency is that we add organic acids to lower the pH of the washing water. Now if I read the document of your first link, there is written that the pH value should be kept between 7,2 to 7,6 to keep a high active chlorine concentration. When I look at the following graph:

http://www.edstrom.c....cfm?doc_id=164

I would tend to say that our process is more effective (pH=4,0) as the active chlorine concentration at this pH value is higher than at pH=7,2.
So what would be the best pH value in your opinion?

One thing that surprised me was that that most of the refs seemed to depend on quite old data (pre 2000). People have become rather more sensitive with respect to residues these days. I found this link detailing the procedure whereby one of the other newer chemicals for this type of application was approved. May be interesting to you.

http://www.foodstand...les/A393_FA.pdf.

The link is indeed very interesting and it is strange that there is no newer data available (at least I didn't find any).
What I do not understand is that the disinfecting process of raw vegetables is mentioned in the GHP for caterers issued here in Luxembourg, but there is actually no list of approved products.

The problem could be that we are a small country with not many experts in the food sector and so I can understand that there can not be as many regulations, recommandations as in the US, Canada or Australia where you have a lot more people to discuss these issues and work on them...
But alas this does not solve my problem so I guess that I will have to refer to the publications of these countries...

So, first of all I'll ask our supplier whether our product is approved for food contact somewhere...

Thanks a lot for taking the time to answer!!!

Regards,
Max

[Charles.C]

Dear Max,

I agree with yr interpretation of the chlorine function. I presume you have monitored the available chlorine variation with washing time already. It will probably drop significantly depending on the input material quantity /cleanliness ?

Regarding pH, I think the choice relates to some safety compromises regarding chlorine gas - eg see the link -

http://dspace.cns.ks...zRivera2005.pdf.

"The effects of pH on chlorine dissociation indicate that at pH 7.5 or greater the quantity of chlorine available as active hypochlorous acid (HOCL) is limited, rather, chlorine exists mainly as inactive hypochlorites (OCl-). If the pH of the wash water decreases below 4.0, then chlorine gas may be formed which is a health hazard for employees (IFPA, 2001). Therefore, the pH of the water should be maintained between 6.0 and 7.5 to ensure adequate and safe chlorine activity. The percentages of chlorine as HOCl at pH 6.0 and 8.0 are about 97% and 23%, respectively (WHO, 1998)."
Other refs (eg http://www.davisfres...s_washwater.pdf ) specify 6.0 directly as a limit to avoid chlorine gas production
The link which I added previously is being even more cautious I guess (official proposal maybe).

One other ref. I noticed also has some HACCP related evaluations-comments, eg a possible CCP as - . "Example: Hydro-cooler water must have a chlorine level of 100 to 150 μL L-1 total chlorine and a pH of 6.0 to 7.5" http://usna.usda.gov...4foodsafety.pdf.




Rgds / Charles.C

Edited by Simon Timperley, 22 August 2006 - 09:12 PM.

[Max]

Dear Charles,

thanks a lot for all of the information you gave me. I think that this will be very helpfull in for the risk assement we will have to carry out on these products!



Regards,
Max

[Charles.C]

Dear Max,

Happy to assist. I might be eating some of your product sometime.

Rgds Charles.C

[Max]

Dear Max,

Happy to assist. I might be eating some of your product sometime.

Rgds Charles.C

Well if you come to Luxembourg one day or if you jsut drive trough (we also supply some gas stations with sandwiches...) then you might. In that case, I'm always available for some hits for visiting...

Regards,
Max

[Julia]

Anyone here use Ozone in the water to disinfect?

We use it at several of our facilities and it's been working really well.

[Jean]

Hi!

Can anyone provide any other alternatives for vegetable sanitization other than chlorine?

Thanks in advance.

J

[Simon]

Hi!

Can anyone provide any other alternatives for vegetable sanitization other than chlorine?

Thanks in advance.

J

Anyone got experience of vegetable sanitization to share with Jean?

[Charles.C]

Dear Jean,

What kind of other alternatives/objectives are you interested in ? -

1 "chlorine" covers straight chlorine gas, or things like hypochlorites plus the swimming pool thing above (Cl-thiocyanate or something, plus ClO2 (very low/no smell/odour) used to be favoured by the japanese IMEX.
2 There are also hypobromites / hypoiodites commercially used (low smell / odour) plus products of mixing hypoCl/Br to produce a stable solid compound (US) again low smell/odour
3 peracids maybe but tricky to handle.

Somewhere there is another thread here regarding a request for "natural" sanitisers which also contains some more offbeat answers but cannot currently find it.

Rgds / Charles.C

[Jean]

Hi Charles,

I have heard of peroxide compounds being used for sanitizing vegetables and fruits in food service sectors, please correct me if I am wrong.

[cazyncymru]

Hi Charles,

I have heard of peroxide compounds being used for sanitizing vegetables and fruits in food service sectors, please correct me if I am wrong.

Jean, i've used a peroxide compound when packing UHT products in cartons (tetra or combiblock) to sanitise the carton before the product is dispensed and sealed