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Shelf life of plastic materials to come into direct contact with food

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Carolina S.

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Posted 25 February 2021 - 01:00 PM

Hello!! I would like to know your opinion regarding the shelf life of plastic materials to come into direct contact with food. From what I have seen in general suppliers have assigned a validity of 1 year from the date of production. However, I have other suppliers that for the same product (same characteristics) already assign 2 years of validity. I don't understand... I understand the validity for plastic films, for example with corona treatment, anti-fog effect. But for a simple PA/PE film/bag I don't understand. For example, in my company we have the cutting and rewinding process. We have to consider the validity of the supplier that supplies us with the reels. We don't work only by order but we also make stock. I have had some difficulty in making sure that the shelf life imposed by the supplier is met. Suppliers also impose minimum order quantities on us which makes this difficult to manage. I don't know how I will get around this in an audit. 
 


Scampi

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Posted 25 February 2021 - 01:48 PM

Have you had your packaging tested in a lab?  

 

If you have target characteristics  (tensile strength, vapour barrier, colour fade etc.) a lab should be able to mimic time/temp/light exposure and produce an actual date for you


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Evans X.

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Posted 25 February 2021 - 02:41 PM

The plastic if stored correctly will have a long shelf-life. As Scampi mentioned a lab can mimic your storage conditions and give you a result and since its gonna take long you can show the intermediate results in an audit (eg the results taken in 3-6-9-12-15-... months up to the date when it shows signs of deterioration or you feel satisfied if you set yourselves a time frame).

If your storage conditions are not stable, you should also consider conducting a shelf-life analysis in the highest and lowest observed temperature and humidity.

 

A simpler way and propably cost-effective would be for you to retain samples from a certain production lot and send periodically for testing. This way you will have your actual storage conditions through the whole testing period and the lab won't have to charge you for this, apart from the analysis cost.



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Carolina S.

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Posted 25 February 2021 - 02:56 PM

Thank you both very much for your answers.
 
We don't have the capacity to do that kind of analysis in our site. We would have to use an external lab.
But that would be very expensive, we have a wide variety of products with different specifications. 
Not to mention that I not only have to deal with the products that we produce and handle, but also with traded goods. I have suppliers giving a 6 month shelf life for PA/PE vacuum bags. 


Foodworker

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Posted 27 February 2021 - 01:21 PM

This is a subject that I tend to get annoyed about.

 

I also find that many suppliers put an unmanageable short life on a product which in most cases is not going to deteriorate for many years.There are products which require a defined shelf life, particularly the newer, biodegradeable types but many, many simpler products do not.

 

I have often gone back to the supplier and obtained a written assurance that the product will not lose its characteristics for several years. I have found also that the Technical Managers of some companies were unaware that the marketing literature even had a shelf life mentioned.

 

The cynic in me says that they do this to encourage repeat sales more frequently.

 

Challenge your suppliers to justify it.



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Charles.C

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Posted 01 March 2021 - 07:23 AM

 

Hello!! I would like to know your opinion regarding the shelf life of plastic materials to come into direct contact with food. From what I have seen in general suppliers have assigned a validity of 1 year from the date of production. However, I have other suppliers that for the same product (same characteristics) already assign 2 years of validity. I don't understand... I understand the validity for plastic films, for example with corona treatment, anti-fog effect. But for a simple PA/PE film/bag I don't understand. For example, in my company we have the cutting and rewinding process. We have to consider the validity of the supplier that supplies us with the reels. We don't work only by order but we also make stock. I have had some difficulty in making sure that the shelf life imposed by the supplier is met. Suppliers also impose minimum order quantities on us which makes this difficult to manage. I don't know how I will get around this in an audit. 

 

 

Hi Carolina S

 

A previous thread here requested info. on published shelf lives of plastics. I attempted a literature search on this topic and found some limited Book data for, IIRC, a few types of plastic which I posted here (somewhere). However, a major caveat, analogous to food, is that operational shelf lives may depend on specific conditions of usage.

 

For example, "standard" PE sheets used for pre-wrapping seafood worked ok for ambient use but, after a few weeks delay, failed to protect  frozen product. Result - freezerburn.


Kind Regards,

 

Charles.C


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Hoosiersmoker

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Posted 03 March 2021 - 08:37 PM

Our auditors have always marked shelf life as N/A on our audits but we manufacture paperboard packaging. Our specifications state that the product is safe as long as outer packaging remains in tact, other than that we give no "shelf life" or "expiry" information.



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beautiophile

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Posted 04 March 2021 - 01:14 AM

This is a subject that I tend to get annoyed about.

 

I also find that many suppliers put an unmanageable short life on a product which in most cases is not going to deteriorate for many years.There are products which require a defined shelf life, particularly the newer, biodegradeable types but many, many simpler products do not.

 

I have often gone back to the supplier and obtained a written assurance that the product will not lose its characteristics for several years. I have found also that the Technical Managers of some companies were unaware that the marketing literature even had a shelf life mentioned.

 

The cynic in me says that they do this to encourage repeat sales more frequently.

 

Challenge your suppliers to justify it.

BRC has recognised the issue and add some more requirements for such new materials e.g. shelf-life, allergen, microbiological. The problem is they don't give clear guidelines so that you have to register (buy) their training programmes (razor and blades model). This leaves so many confusions in interpretation, even to auditors.



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po6ito23

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Posted 04 March 2021 - 08:11 AM

Hi! I'm also from packaging company,

1. Our "best before date" for our raw materials is based on our supplier's declared best before date

2. For our finished goods, laminated films (plain and printed) "best before date" is 24 months with storage condition of ambient temperature, dry and away from direct heat or sunlight. We're the one who set this best before date based on our studies and tests for its functional use.



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HaloQA

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Posted 05 March 2021 - 03:59 PM

This is a subject that I tend to get annoyed about.

 

I also find that many suppliers put an unmanageable short life on a product which in most cases is not going to deteriorate for many years.There are products which require a defined shelf life, particularly the newer, biodegradeable types but many, many simpler products do not.

 

I have often gone back to the supplier and obtained a written assurance that the product will not lose its characteristics for several years. I have found also that the Technical Managers of some companies were unaware that the marketing literature even had a shelf life mentioned.

 

The cynic in me says that they do this to encourage repeat sales more frequently.

 

Challenge your suppliers to justify it.

 I so agree with this comment. We had the same problem with our plastic films (short shelf-life and minimum quantity orders). And in fact, one day I found a film which was few years old but looked completely intact and good. We processed it (not for market, just as test) and it worked. Then we wondered why so short shelf-life. We sent the film to our supplier to test the properties and all the values were exact the same as the ones after manufacturing it (but supposedly, according to the specifications they provided, this was "expired"). Luckily we managed to get written confirmation that the product held its characteristics for longer period than the one established on their specifications.

 

I also think this is just a marketing tool, but which has a great impact on environment (up to now we were throwing quite some film per year because of "expiration"). Since then I also try to push suppliers to get longer assurance on shelf-life.



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Carolina S.

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Posted 05 March 2021 - 07:23 PM

This is a subject that I tend to get annoyed about.

 

I also find that many suppliers put an unmanageable short life on a product which in most cases is not going to deteriorate for many years.There are products which require a defined shelf life, particularly the newer, biodegradeable types but many, many simpler products do not.

 

I have often gone back to the supplier and obtained a written assurance that the product will not lose its characteristics for several years. I have found also that the Technical Managers of some companies were unaware that the marketing literature even had a shelf life mentioned.

 

The cynic in me says that they do this to encourage repeat sales more frequently.

 

Challenge your suppliers to justify it.

 

I have tried to talk to the suppliers but they are not cooperative. And they justify that the products may change if past the defined expiration date. I can't argue against this fact. 



Carolina S.

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Posted 05 March 2021 - 07:35 PM

Hi! I'm also from packaging company,

1. Our "best before date" for our raw materials is based on our supplier's declared best before date

2. For our finished goods, laminated films (plain and printed) "best before date" is 24 months with storage condition of ambient temperature, dry and away from direct heat or sunlight. We're the one who set this best before date based on our studies and tests for its functional use.

 

Hi,

 

So imagine that the raw material supplier sets a shelf life of 1 year. Then you use this raw material in the final product and you give it a 2-year shelf life?
 
There will come a point where your final products will be composed of expired raw materials. Do you see what I mean? 


Carolina S.

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Posted 05 March 2021 - 07:43 PM

We are implementing the BRC Pack. 
 
I have never been through a certification audit. From your experience, is this issue of validity always checked in an audit? 


Charles.C

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Posted 05 March 2021 - 09:09 PM

 

Hi,

 

So imagine that the raw material supplier sets a shelf life of 1 year. Then you use this raw material in the final product and you give it a 2-year shelf life?
 
There will come a point where your final products will be composed of expired raw materials. Do you see what I mean? 

 

Hi Carolina,

 

Not a Packaging person but I speculate that any "declared" shelf life of food packaging would be based on some specific (critical?)  characteristic(s), eg permeability, being maintained within a specific limit for a given time under standardised conditions.

 

But I also speculate that such a declaration would not necessarily, accurately, correspond to user-implemented (unknown?)  product/packaging storage conditions for a paired combination so yr imagined interpretation may not reflect reality ?

 

During food audits, cannot recall any auditor ever asking about such a packaging datum. Shelf-life queries invariably focus on paired, product testing data being satisfactory.

 

I have just done a quick browse around the internet seeking any quantitative, meaningful, shelf-life data for food packaging. Result - Nada.

 

PS - Here is a collection of analogous threads on this forum. You will see there is a fairly consistent "theme" - difficulty in interpretation,  lack of data. :smile:

 

https://www.ifsqn.co...ging-materials/

https://www.ifsqn.co...lastic-bottles/

https://www.ifsqn.co...ging-materials/

https://www.ifsqn.co...aging-material/

https://www.ifsqn.co...food-packaging/

 

Here is a, maybe typical, shelf life specification (evasion?) taken from post8 in last link above -

 

Attached File  shelf life corrugated container.PNG   97.35KB   1 downloads

 

I also noticed this "comment" in a Packaging article -

 

Predicting the Right Package

Numerous models exist to predict what package is required to achieve a desired shelf life. However, the models only serve as a guide to define the range of acceptable barrier properties while their algorithms highlight concerns. Because oxygen, water, and carbon dioxide affect shelf life, permeabilities need to be assessed for the environment to which the food will be exposed; this often does not align with standard information. For example, standard data parameters for oxygen transmission rate (OTR) is 0%–100% at low humidity and high temperature. However, gradients for packaged food usually range from 0% to 21% of oxygen at relative humidities of 20% to 90% and at temperatures of -5°F to 110°F. Predictive OTR values for different oxygen, humidity, and temperature conditions are inherently flawed for polymer and paperboard structures that alter significantly as a function of different parameters. Likewise, predictions of water vapor transmission based on different gradients at different temperatures are problematic.

Attached File  Packaging that meets shelf life goals.pdf   1.41MB   17 downloads

 

This link may also be of some interest -

 

https://packaginggur...food-packaging/


Kind Regards,

 

Charles.C


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Foodworker

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Posted 06 March 2021 - 10:54 AM

It is rare to have it audited as a specific topic but when I was auditing I often found materials - plastics, glues, inks, lubricants and even paper) on the shelves beyond their shelf lives during the site inspection. It may have been that there were technological reasons for this so I used to raise it as a minor and their corrective action was normally to check with the supplier and in every case the supplier gave a written extension.

 

In one case the root cause was stated as the supplier provided incorrect information, and they changed supplier.

 

Clearly this is not possible in all instances, but if it is a simple material, with no technological evidence for deterioration, there is no need for a shelf life.



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beautiophile

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Posted 08 March 2021 - 01:37 AM

 

Hi,

 

So imagine that the raw material supplier sets a shelf life of 1 year. Then you use this raw material in the final product and you give it a 2-year shelf life?
 
There will come a point where your final products will be composed of expired raw materials. Do you see what I mean? 

 

I see your concern. The packaging industry has lasted nearly 2 centuries and has become so practical that such things are rarely asked or examined outside professional R&Ds or labs.

 

AFAIK, the shelf-life of packed food hardly extends longer than 1 year. A life cycle of a packaging material must be longer because of post-production dispatch, storing, shipment, etc. Then that 2-year shelf-life makes sense.

 

Nevertheless, either packaging manufactures or food packers or both sides have to retain a proper evidence of such 2-year shelf-life claim. And it seems people with materials science knowledge can't get involved by some reasons, hence others keep hitting the wall.

 

There's a kind of real-time examination of material performance. The point is to evaluate the degradation throughout the life time. Let's say you receive a batch of packaging material from a supplier and extract 10 samples for archiving & later checking. Every 3 months, you take 1 sample to test for quality & safety (e.g.  migrations as EU 10/2011). The 10th sample can give the property information of 2-year-old packaging although your archiving condition doesn't simulate the actual usage like displaying in supermarkets.


Edited by beautiophile, 08 March 2021 - 01:41 AM.





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