7 replies to this topic

[ilonar]

Hello,

 

I know that the topic of metal detection was over and over discussed in this forum, but my questions are hopefully in a way different than the ones that were already found in the previous posts. But also the approach to the subject can be different than 10 years ago.

 

We are a fresh fruit and vegetable packaging company and we didn't have any metal detectors. We did a risk assessment according to BRC and we validated the fact that we don't need to have a metal detector (we have a  metal control procedure that checks every day used scissors and knives. plus if we go through the metal detector decision tree we end up at no metal detector needed). But one of our clients is asking for metal detector for the products packed for him. So we have now 2 new metal detectors and we will also have a second hand one. So this means that on 3 packaging lines we are using metal detector, while on two lines we don't use it. So I still have the validation report that we don't need metal detector (to cover the 2 lines without the metal detector) and the validation report for the use of the metal detector as a requirement from that specific client. Do you think that this will be accepted by the auditors during an audit (besides that, there is no space where to put a metal detector on the other 2 lines).

 

I've seen that the presence of the metal detector is mostly considered as a CCP in discussions on this forum. One of the guidelines on metal detection that I've recently read was saying that depending on the situation it can be a CCP or CP. Also, a document that I've seen from a consultancy office is considering it as a CP. Our client is more concerned of contamination from primary production than at our packaging side. Also, although we packed the product and we passed it through a metal detector, it can still be later contaminated with metal by means of intentional contamination (punnets for soft fruit have small holes in them which are allowing for the fruit to breath, so anyone can still put a metal in the packaging after it leaves our company). So I would like to make a CP out of it (and of course it is not used on all packaging lines).

 

In order to test the metal detector, we have to use sample tests with ferrous/ non-ferrous/ stainless steel inside. In BRC, it is only specified that the sensitivity of the test samples (size of the metal used in the sample) should be determined based on risk. We checked with our client and 1,5 mm /2 mm/3 mm is enough for him. The metal detector has some premade samples of 1,2 mm/1,5 mm/2,25 mm to adjust the sensitivity of the equipment. The manufacturer will replace these samples for custom made ones. We would like to plan in advance and try to have the "correct" test samples. We can never know when a new client or the existing one will ask for a higher sensitivity. I was looking up information about sensitivity, and there are several documents with different values. It seems that the most frequent ones are the ones in  this table:

 

PRODUCT HEIGHT

DRY PRODUCT

INCLUDING NON-METALLISED FILM PACKED PRODUCTS

WET PRODUCTS

and METALLISED FILM PACKED PRODUCTS

ALUMINIUM FOIL PACKED PRODUCTS

Ferrous

Non-Ferrous/

Aluminium

Stainless Steel 316

Ferrous

Non-Ferrous/

Aluminium

Stainless Steel 316

Ferrous

Non-Ferrous/

Aluminium

Stainless Steel 316

Up to 50mm

1.0

1.2

1.5

1.8

2.5

3.5

1.0 – 4.0

-

-

50mm - 100mm

1.2

1.5

2.0

2.0

2.8

4.0

1.0 - 4.0

-

-

100mm – 150mm

1.5

2.0

2.5

2.5

3.5

4.5

1.0 – 6.0

-

-

150mm – 200mm

1.8

2.2

3.0

3.0

4.0

5.0

1.0 – 6.0

-

-

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

If the product height is the one of the final packaging and not the one of the individual product (blueberries have between 10-20 mm), then we are still in the entire area from "up to 50 mm" to "150-200 mm", because we can pack 125 g blueberries in a combination of punnet and cover with a height of 30 mm or 500 g strawberries  in a combination of punnet and cover with a height of 180 mm. They will be packed on the same packaging line on the same day. But then are  blueberries, grapes and strawberries dry or wet product? I received this answer from the manufacturer:

 

"Sensitivity is always product related, fresh products are more difficult to detect then dry products, as an example; in a fresh chicken filet a detector can detect less metal then in the same filet but then deep frozen. Also the aperture size of the detector will influence the sensitivity levels, the larger the aperture the less a detector can detect.

 

Products with a high product effect (this effect will limitate the sensitivity) can have different sensitivity levels if the volume of the packs are different. I am not aware of a standard in the “soft fruit industry”.

 

I can send you the samples 1.0/1.2/1.5 but I am not sure if you will detect this, because you have to change the % and this might give false rejects, due to product effect."

 

Does anyone have experience with sensitivity of metal detectors? We might also ever have to pack for Tesco and I would also like to know what is the sensitivity that they are requesting. 

 

[Chella2700]

Hi,

 

I had the similar issue whilst my time with added value poultry product manufacturing. To make it as a CP or CCP it all depends upon whether the product is ready to eat or wash before use. If it is wash before use, then you can have your metal detector as CP.

 

For regarding the sensitivity, it changes product to product and all other factors as you mentioned plays a role. The possible way to determine the sensitivity is by doing trials with all the products and fix the lowest test piece size which didn't have false rejects (or less false rejects). You can do it in conjunction with your manufacturer and get a letter after the exercise with the outcome, this will serve as your validation document for the individual metal detector.

[Robert Rogers]

as mentioned there are several factors that can affect the metal detector detection capability.

First is physical size of detector opening i.e. larger the opening the less the detection capability

Secondly they work on a conductive principle meaning any conductive material passing through will have an effect on the detector. This is also why you will see different detection capability between the metal types, Ferrous  is typically easier to detect than SS, Fe is conductive and magnetic, SS is non conductive and non magnetic making it more difficult to identify in metal detection.

Products that have conductive natures to them (high moisture, iron, salt, acidity and temperature) like fresh fish produce a higher product signal to the detector that must be compensated for by reducing sensitivity. Dry non-conductive products like rice, grains, and powders typically do not generate any product signal and therefore are able to be inspected at higher sensitivities improving detection capability.

 

If the product has variable conductive nature i.e. temperature variations, moisture variations etc. the settings will need to allow a broader range of product again by reducing sensitivity affecting detection capability.

 

Mettler Does offer free product testing in our application center where companies can send product in for testing and they will perform product tests on various system sizes and types and report back the capability.

 

X-ray is less susceptible to the conductive nature of the product and typically in conductive product applications can out perform a metal detector.

 

Product testing will reveal what is possible.

 

If product conditions or detector size are not areas available for change or modification then the limitations will be due to product conditions not necessarily detector performance

[Simon]

Oh hello Robert.

 

I trust Robert won't mind me saying he is probably the worlds leading authority on metal detection and x-ray inspection.

Robert has conducted several webinars with IFSQN over the years.

 

Here are a few recordings I'm sure you will find useful.

 

https://www.ifsqn.co...e-products-r174

https://www.ifsqn.co...r-now-what-r128

https://www.ifsqn.co...ght-choice-r111

https://www.ifsqn.co...ion-program-r82

 

Regards,

Simon

[Charles.C]

Hi ilonar,

 

I deduce you make no use of metal-linked conveyors.

 

I also deduce you will be simultaneously implementing 2 different haccp/CCP plans for the same process. Interrresting.

 

I cheerfully predict that you may anticipate an interesting BRC auditorial discussion after you add any metal detector as a CP. (or a CCP for that matter).

 

However if, for BRC, you have been able to run 2 fresh product (RTE?) lines without a MD, I guess anything is possible.

 

PS - actually you can find some examples where the MD is one of PRP, CP, OPRP, CCP.  However, if BRC stick rigidly to Codex-haccp, I think this excludes the 2nd and 3rd options.

[ilonar]

Thank you for your answers.

 

I talked with other companies involved in fresh fruit and vegetables and everybody was "shocked" that we will have metal detectors. Nobody is using metal detectors for packing fresh (not cut or processed) fruit and vegetables. The only time that someone used one was when they had to cut a fuit (because it was passing through a machine with a knife). it also seems that the sizes we received from our client to be used to set up the metal detectors (1,5 mm Fe/2,0 mm N-Fe/ 3,0 mm RVS) are the commonly used ones for soft fruit, so I will go for theset when ordering the sample sizes. 

 

As I wrote before, we never had a metal detector. We had a risk assessment with validation that we don't need one. BRC has a decision tree for determining if we need a metal detector and also when applied it, the answer was no (just like in case of the other companies). it is also difficult to say exactly if the product is RTE.  According to Regulation 2073/2205, "ready-to-eat" means food intended by the producer or the manufacturer for direct human consumption without the need for cooking or other processing effective to eliminate or reduce to an acceptable level micro-organisms of concern. Fresh blueberries and strawberries are normally not intended to be cooked before consumption, but it is expected to  wash them. This way, dust and part of the microorganisms on the surface will be eliminated. And with them, probably, but not necessarily, small parts of metal can also be removed (although nobody would like to find a metal piece while washing blueberries). 

 

The product is not our property, we are just a service provider for packing and storage (we don't have suppliers of raw material, only clients who purchase their product from their suppliers and let it delivered to our address). This also means that our HAACP study doesn't identify any risks present in the product as raw material, just during the process steps for handling. When we assess the risk of contamination with metal pieces from breakage from knives (used to open boxes/pallets), we have probability small and severity high. As we use the risk matrix table with 3x3  (small, medium, high), the risk factor is 3 and we don't need to apply the decision tree (from BRC and Codex) to determine if we have or not a CP/CCP. So I decided that I will call the metal detector  an "in-line process control". To comply with BRC I set up a procedure to test the metal detector (start-up, every hour, after break, changeover, finish), set-up sensitivity for different product in different packaging, procedure for how to handle rejected product, failure of machine; train employees; validate use of metal detector. And hope that during the next audit everything will be in order.  

[Charles.C]

Thank you for your answers.

 

I talked with other companies involved in fresh fruit and vegetables and everybody was "shocked" that we will have metal detectors. Nobody is using metal detectors for packing fresh (not cut or processed) fruit and vegetables. The only time that someone used one was when they had to cut a fuit (because it was passing through a machine with a knife). it also seems that the sizes we received from our client to be used to set up the metal detectors (1,5 mm Fe/2,0 mm N-Fe/ 3,0 mm RVS) are the commonly used ones for soft fruit, so I will go for theset when ordering the sample sizes. 

IMEX 200g - 2kg frozen packs,(not vegetables/fruit) the 1.5 and 3.0 may be problematic. You might consider giving the MD manufacturer some of your samples.

 

As I wrote before, we never had a metal detector. We had a risk assessment with validation that we don't need one. BRC has a decision tree for determining if we need a metal detector and also when applied it, the answer was no (just like in case of the other companies). it is also difficult to say exactly if the product is RTE.  According to Regulation 2073/2205, "ready-to-eat" means food intended by the producer or the manufacturer for direct human consumption without the need for cooking or other processing effective to eliminate or reduce to an acceptable level micro-organisms of concern. Fresh blueberries and strawberries are normally not intended to be cooked before consumption, but it is expected to  wash them. This way, dust and part of the microorganisms on the surface will be eliminated. And with them, probably, but not necessarily, small parts of metal can also be removed (although nobody would like to find a metal piece while washing blueberries). 

By "expected" do you mean labelled ? IIRC there is some "history" over the washing aspect for vegetables, fruit I am less sure. TBH, IMO, RTE is RTE but i appreciate yr spin.

 

The product is not our property, we are just a service provider for packing and storage (we don't have suppliers of raw material, only clients who purchase their product from their suppliers and let it delivered to our address). This also means that our HAACP study doesn't identify any risks present in the product as raw material, just during the process steps for handling. When we assess the risk of contamination with metal pieces from breakage from knives (used to open boxes/pallets), we have probability small and severity high. As we use the risk matrix table with 3x3  (small, medium, high), the risk factor is 3 and we don't need to apply the decision tree (from BRC and Codex) to determine if we have or not a CP/CCP. So I decided that I will call the metal detector  an "in-line process control". To comply with BRC I set up a procedure to test the metal detector (start-up, every hour, after break, changeover, finish), set-up sensitivity for different product in different packaging, procedure for how to handle rejected product, failure of machine; train employees; validate use of metal detector. And hope that during the next audit everything will be in order.  

I suggest to justify (eg references) yr risk assessment/SOP/frequency in advance of the audit. The designation is atypical as you are probably aware, but since it is not a CCP .........

 

Hi ilonar,

 

I assume that the other Producers which you reference above have attained BRC Certification. Should be a good indicator assuming equivalent processes.

 

Here are a few BRC Guideline comments  for Fresh Produce which may be of interest  -

 

 Metal Detection-Fresh Produce.pdf   100.93KB   103 downloads

Edited by Charles.C, 27 November 2019 - 02:59 PM.
added

[jess.g]

 

 Fresh blueberries and strawberries are normally not intended to be cooked before consumption, but it is expected to  wash them. This way, dust and part of the microorganisms on the surface will be eliminated. And with them, probably, but not necessarily, small parts of metal can also be removed (although nobody would like to find a metal piece while washing blueberries). 

 

Off topic, slightly.

Last September, in Australia, we had an incident where a disgruntled employee was inserting needles into strawberries. It wasn't caught until the strawberries reached the public and there was a huge recall initiated. 

 

It's also not common (in my experience) for people to wash blueberries, strawberries or raspberries before eating. 

 

I do recall that a cookie dough manufacturer was sued (not sure of outcome) because they *knew* that the product was being eaten prior to cooking (not as intended) and didn't take steps to make the raw cookie dough safe.