Transitioning from hot fill to cold fill for Low acid refrigerated dairy product

Hi All,

I am working on a sustainability project involving the transition from a non-recyclable packaging material (High Impact Polystyrene) to a more recyclable material, most likely PET however other materials are being considered. 

One of the challenges I am facing is the temperature limits that PET and other recyclable materials have. The product is a low acid dairy dessert product, the pH of the final product is between 6.4-6.7 with a high water activity. The proposed solution that I have been tasked with is to transition the filling process from a hot filling process to a cold fill process in order to use this new material, there are issues surrounding the viscosity of the product that come with this but that is not why I am writing today. The main issue I want your guys thoughts on is the food safety risks that come with this. 

The product is heat treated at 95^oC for 5 minutes and is filled into its packaging at a minimum of 65^oC. The product is non-shelf stable and is kept refrigerated during storage and throughout the supply chain. The proposed fill temperature to enable the new packaging is cold, so around 4^oC. I have been informed by an outside advisor that psychrotrophic B.cereus spores may potentially be present on the packaging and without that final hot filling process this may be an issue. I have also been informed that yeasts and moulds could potentially be present on the packaging and this could potentially be another failure point. If there are other pathogenic or spoilage microbiological concerns you think I need to be aware of please let me know.

Antimicrobial additives are in scope for this project and based on the limited literature I have read Potassium sorbate and Nisin are potential contenders for inhibiting B.cereus, Nisin however is particularly expensive and does not handle the heat treatment process particularly well. I wanted your thoughts on any other mitigations that could be used for this project. 

Another route that could potentially be investigated is going about the process through the packaging, there are potential additives that could be used to increase the temperature that PET can endure during the hot filling process. This then introduces concerns about the chemical leaching that could occur at elevated temperatures.

If there are any processing changes you think may work I would love to hear them.

Thanks for your time if you've made it this far,

If you've got any further questions please sing out,

Kind regards

Hi Matt,

:welcome:

Welcome to the IFSQN forums.

This is a significant process change and the main issue is you are going from a product that is more or less pasteurised in the pot to one that is going to be susceptible to post process (95 C heat treatment) contamination from plant/equipment/filler and the packaging. I would be conducting a full HACCP review prior to proceeding.

The level and type of contamination will depend on your plant hygiene post heat treatment and could potentially include pathogens you haven't mentioned such as pathogenic E. coli, Salmonella and Listeria. Your current process may have masked levels of post 95 C heat treatment contamination because of the hot fill process. Also as you have identified there may be packaging issues to deal with but these tend to be Y&M related so may be more of a concern if the product is particularly susceptible to Y&Ms.

One easy solution would be to change to aseptic filling but that usually requires quite some capital investment.

Be interesting to know the current shelf life and expected new shelf life.

Kind regards,

Tony

what is a low acid dairy desert product?  maybe an example.  pudding, custard?

non shelf stable fluid milk products are routinely packaged cold in PET or HDPE bottles with no controls to address organisms that may be inside the packaging.  While packaging at 65C you are killing many organisms, however there are still spoilage organisms that will survive this temperature.

Maybe I'm not visualizing the product and process correctly.   If would seem to me that there would be a far greater risk of introduction of microorganisms after the product is cooled and transferred to packaging than the package itself.

There are hot fill pet and other plastic resins available.  As well as other materials.   Is PET really recycled more than HIPS.  honest question.  

I seem to be on a HPP kick.  is that an option?   or aseptic like Tony suggested?  

...   Is PET really recycled more than HIPS.  honest question.  

 

...

The literature I've read suggests the vast majority (~90%) of polymer based items that could be recycled just go to landfills.

It makes for decent marketing though apparently.  Warm fuzzies all around.

what is a low acid dairy desert product?  maybe an example.  pudding, custard?

 

non shelf stable fluid milk products are routinely packaged cold in PET or HDPE bottles with no controls to address organisms that may be inside the packaging.  While packaging at 65C you are killing many organisms, however there are still spoilage organisms that will survive this temperature.

 

Maybe I'm not visualizing the product and process correctly.   If would seem to me that there would be a far greater risk of introduction of microorganisms after the product is cooled and transferred to packaging than the package itself.

 

There are hot fill pet and other plastic resins available.  As well as other materials.   Is PET really recycled more than HIPS.  honest question.  

 

I seem to be on a HPP kick.  is that an option?   or aseptic like Tony suggested?  

Yeast/Mold can be equally as present as B. cereus in your product, and without a heat fill you're still extremely susceptible to these pathogens as well as a slew of others. Your testing plan should be dependent on how your filling process is set up. Additional pathogens of concern in a cold fill would be Listeria mono. and potentially E. coli (maybe run STEC panels). Some products require challenge studies in addition to shelf life studies in order to ensure the production process meets regulation since the FDA and USDA do no illicitly give step by step details on every product/matrix type.

Additionally, I agree with King here, maybe try HPP as an additional treatment/application. I've heard/seen some promising results from this in industry. 

The literature I've read suggests the vast majority (~90%) of polymer based items that could be recycled just go to landfills.

 

It makes for decent marketing though apparently.  Warm fuzzies all around.

The major reason for the packaging change is due to a change in legislation banning the use of HIPS in New Zealand. My understanding, within my country at least, is that recycling companies no longer see it as economically viable to continue recycling this material and instead makes more sense, commercially speaking, to send it to landfill.

The government is attempting at least to make a more "circular" economy, whatever the hell that means.

Hi Matt,

 

:welcome:

 

Welcome to the IFSQN forums.

 

This is a significant process change and the main issue is you are going from a product that is more or less pasteurised in the pot to one that is going to be susceptible to post process (95 C heat treatment) contamination from plant/equipment/filler and the packaging. I would be conducting a full HACCP review prior to proceeding.

 

The level and type of contamination will depend on your plant hygiene post heat treatment and could potentially include pathogens you haven't mentioned such as pathogenic E. coli, Salmonella and Listeria. Your current process may have masked levels of post 95 C heat treatment contamination because of the hot fill process. Also as you have identified there may be packaging issues to deal with but these tend to be Y&M related so may be more of a concern if the product is particularly susceptible to Y&Ms.

 

One easy solution would be to change to aseptic filling but that usually requires quite some capital investment.

 

Be interesting to know the current shelf life and expected new shelf life.

 

Kind regards,

 

Tony

Hi Tony, 

Thanks for your insight, HACCP review will definitely be within scope for this project, I was just looking to get some initial thoughts on the matter. I am still coming to grips with the finer details of the manufacturing process used, however, the plant has a full Hot Acid/Hot caustic CIP system in place as standard with a sanitiser step optionally. I doubt the other post process microorganisms mentioned would survive this and be able to contaminate the product post heat treatment, however, definitely something to be aware of so thank you for that. I failed to mention previously but the product was held following pasteurisation at 70^oC until filling, this would likely limit any post process contamination especially from any pathogens.

Environmental sampling is regular within the plant and this product requires micro clearance to be shipped out, however, I know this isn't perfect and things can get through this. 

Aseptic filling is out of scope for this because as you mentioned it has a huge capital investment behind it.

The current shelf life is 35 days and we are trying to achieve the same shelf life with the new process. I am not experienced enough to know if this is a ridiculous thing to expect, but I suspect it might be?

what is a low acid dairy desert product?  maybe an example.  pudding, custard?

 

non shelf stable fluid milk products are routinely packaged cold in PET or HDPE bottles with no controls to address organisms that may be inside the packaging.  While packaging at 65C you are killing many organisms, however there are still spoilage organisms that will survive this temperature.

 

Maybe I'm not visualizing the product and process correctly.   If would seem to me that there would be a far greater risk of introduction of microorganisms after the product is cooled and transferred to packaging than the package itself.

 

There are hot fill pet and other plastic resins available.  As well as other materials.   Is PET really recycled more than HIPS.  honest question.  

 

I seem to be on a HPP kick.  is that an option?   or aseptic like Tony suggested?  

Hi King,

Its similar to custard, basically a milk product that's been gelled/thickened with starch and carageenan, one of the definitions by our food standards authority is below:

"Dairy desserts can be based on fresh milk, milk powder or milk protein concentrates to which flavours, colours and sweeteners may be added. Dairy desserts mixes typically undergo a heat treatment; and further processed (e.g. whipping and freezing). Heat treatment by pasteurisation or UHT results in the destruction of vegetative cells. Contamination may occur after heat treatment with the addition of further ingredients, or through survival of spores of B. cereus."

As I said to Simon, I forgot to mention, but this product is held hot right up until it is packaged at 65-70^oC and there is rigorous CIP systems in place to limit post heat treatment contamination.

HPP would probably not be in scope for this project as I imagine it is a significant capital investment and am I right in saying HPP is a batch style kill step? will probably be wrong about this though

Hi Tony, 

 

Thanks for your insight, HACCP review will definitely be within scope for this project, I was just looking to get some initial thoughts on the matter. I am still coming to grips with the finer details of the manufacturing process used, however, the plant has a full Hot Acid/Hot caustic CIP system in place as standard with a sanitiser step optionally. I doubt the other post process microorganisms mentioned would survive this and be able to contaminate the product post heat treatment, however, definitely something to be aware of so thank you for that. I failed to mention previously but the product was held following pasteurisation at 70^oC until filling, this would likely limit any post process contamination especially from any pathogens.

 

Environmental sampling is regular within the plant and this product requires micro clearance to be shipped out, however, I know this isn't perfect and things can get through this. 

 

Aseptic filling is out of scope for this because as you mentioned it has a huge capital investment behind it.

 

The current shelf life is 35 days and we are trying to achieve the same shelf life with the new process. I am not experienced enough to know if this is a ridiculous thing to expect, but I suspect it might be?

Hi Matt,

It would be a plus if there are separate full Hot Acid/Hot Caustic CIP systems in place for raw and pasteurised plant/tanks/equipment.

A terminal disinfectant such as Peroxy Acetic Acid would be a plus as well.

The product held following pasteurisation at 70°C until filling, would not be susceptible to post process contamination especially from any pathogens. This cold fill product would be extremely susceptible to post process contamination so hygiene standards will be very important.

I suggest you conduct some trials and sample for Enteros and Y&M and see if you are getting any contamination.

The shelf life of a fresh yogurt which is pH protected is typically a few weeks and dependent on plant/filler hygiene. So achieving 35 days with a low acid product without hot fill may be ambitious.

On the plus side 95°C for 5 minutes is regarded as high temperature pasteurisation and does allow an extended life in low acid products but I don’t apologise for stating it again, hygiene standards post pasteurisation will be very important with the proposed cold fill product.

Kind regards,

Tony