10 replies to this topic

[ewhite]

Hello. I am trying to formalize our shelf life monitoring, and I'm wondering if anyone could provide details for what they do towards monitoring the shelf life of their products. Specifically I'm curious about frequency, method, and level of detail. Thank you for your help!
-Erika

[Charles.C]

Dear ewhite,

A little information about yr products might encourage some responses.

Rgds / Charles.C

[ewhite]

Yes, my product is a frozen fruit bar. We have a pre-established shelf life of one year, but have only done random monitoring in the past. We are looking to formalize our sampling plan, and add microbial testing to our end of shelf life evaluation, however this could be very costly depending on our sample frequency and number. This is why I would like to know what others do in terms of shelf life monitoring and end of shelf life evaluations.

[Anish]

Dear ewhite,

I dont have experience in the stability studies of deep freezed product. But let me share my experience in evaluating dry foods. You may get some idea out of it.

Generally for dry blends & food which is generally kept in the shelf or required to maintain 25deg - 4 kind of studies are generally done - 2 studies using accelerated methods (indirect method) and another 2 following direct methods.

Indirect studies are done by keeping the product at 55deg and 90% RH, another at 40deg and 55% RH

Direct studies are done by keeping the product at at 25deg, 55% RH and another at Room temperaturewithout controlling temperature & humidity.

Then a weekly interval is followed to check for Sensory, Rancidity, Peroxide Value & other important parameters which is a key property of the ingredient (vitamins, minerals ...). Individually packed samples should be used each time - I mean while keeping the sample for stability studies - enough quantity should be kept in the humidity chambers (if you mark it in advance it is good) - so that once taken for analysis should not be kept again.

Also, packaging test such as oxygen permeability & water vapour permeability is done for the package which is used for packing the material - this is required only one time.

After the laboratory analysis the results are analyzed. There is a correlation for indirect studies which is called as Accelerate Aging Equivalency tables, which is used for interpreting the studies. And for direct studies, the samples are kept for the same duration and a little longer than the expected shelf life and analyzed and interpreted.

I have done some project for Pedigree & GSK - in which they use 2.5months @ 55deg at 90% humidity is equal to 2 years of shelf life.

[Charles.C]

Dear ewhite,

I do have some experience of manufacturing deep frozen products (seafood) but not fruit bars. I guess it will be necessary for you to initially select the relevant microbial parameters for control purposes. APC ??

As per previous post, our customer did accelerated testing at non-deep frozen temps so as to get a conclusion in (from memory) approx. 3-4 weeks. This involved microbial testing for 3-4 parameters, eg APC. I don’t know the full procedural details but I expect the technical basis was analogous to earlier post.

Obviously it depends on yr volume of work but, if you yourself lack the technical knowledge, might be cost-effective to pay a 3rd party organisation to do the first time, then borrow the logic. Or maybe the detail is readily available in textbooks (I recall previously looking some time ago and got negative result). I also remember a detailed post on this forum in the past giving some (accelerated) equations also.

Rgds / Charles.C

[ewhite]

Dear ewhite,

I do have some experience of manufacturing deep frozen products (seafood) but not fruit bars. I guess it will be necessary for you to initially select the relevant microbial parameters for control purposes. APC ??

As per previous post, our customer did accelerated testing at non-deep frozen temps so as to get a conclusion in (from memory) approx. 3-4 weeks. This involved microbial testing for 3-4 parameters, eg APC. I don’t know the full procedural details but I expect the technical basis was analogous to earlier post.

Obviously it depends on yr volume of work but, if you yourself lack the technical knowledge, might be cost-effective to pay a 3rd party organisation to do the first time, then borrow the logic. Or maybe the detail is readily available in textbooks (I recall previously looking some time ago and got negative result). I also remember a detailed post on this forum in the past giving some (accelerated) equations also.

Rgds / Charles.C

Thank you Charles and Anish for sharing your experiences, however perhaps you could comment further:

I am familiar with the direct and indirect shelf life testing that was described, and I agree that it is a very complete program. However, I assumed this was mostly used to establish product shelf life, and a lesser program could be used for continued monitoring. Am I just wishful, or does such a thing exist?

In our case, we already have an established shelf life, and no one is asking us to provide the details of why it is set as such. Rather, we would like to provide documentation that we are verifying the shelf life through regular monitoring. I have attached a copy of a form that I created to give you an idea of the parameters I plan on testing. Please let me know if you think this would be sufficient if testing according to our finshed product sampling plan-- 1 bar per 6 pallets, or at least 1 bar per flavor/brand.

Attached Files

•  Basic Shelf Life Evaluation Form.docx   16.58KB   437 downloads

[Esther]

DEar Ewhite

Time ago I attended a course regarding Shelf Life Calculation. A lot of maths formula.
If I am not wrong, I think that an accelerated test is not the most appropiate method for your kind of product,I mean, a frozen product. And also, I would say that micro test will not be useful neither.

The results of an accelerated test are only an " estimation" so you will have to validate it anyway.

First thing is to think about what parameters you think are important in your product to be measured. In your case I would go for organoleptic ones mainly ( maybe some physical parameter also).
If your current sheft life is, lets say, 2 years I would say that organoleptic tests every 3 months would be enough. Other thing is to decide who is going to do those organoleptic tests, whether profesional people ( tasters) or your own people. Of course, first option is more expensive and may not fing the right people.

I wish this can help.

Best regards
Esther

Hello. I am trying to formalize our shelf life monitoring, and I'm wondering if anyone could provide details for what they do towards monitoring the shelf life of their products. Specifically I'm curious about frequency, method, and level of detail. Thank you for your help!
-Erika

[Charles.C]

Dear Esther,

Time ago I attended a course regarding Shelf Life Calculation. A lot of maths formula.
If I am not wrong, I think that an accelerated test is not the most appropiate method for your kind of product,I mean, a frozen product. And also, I would say that micro test will not be useful neither.

All I can say is that for the frozen shrimp involved, accelerated testing / micro. analysis was the decisive procedure employed by the receiver in UK. Rightly or wrongly I hv no idea. You may well be correct.

@ ewhite. Sorry for delayed reply. Only today saw yr post.

I agree with Esther regarding choice. It really depends on you/your product what you want to do.

Personally I have used basic organoleptic / microbial analysis similar to yr form for nominal shelf live validations of 12-18 months. IMO yr concept of routine monitoring is only meaningful when part of an overall shelf life program. Regarding sampling, I used six whole cartons taken from successive daily lots over 3 days giving total 18 cartons. Units of each of the 3 lots were then sampled every 3 months and the results compared to internal specifications. This was done for various product types over a staggered time scheme (the storage space required may not be negligible).

I wondered what the microbial test for CEC meant on yr form ? Count E.coli ?

Rgds / Charles.C

[ewhite]

Thank you Esther and Charles for your insight. I have done some additional research to find some information about frozen foods (trying to focus on fruits), and found that accelerated testing is sometimes done, but I agree that in our case it doesn't make much sense. Our biggest issues come from ice crystals, which on older bars (2x their shelf life) resulted in a slushy- (sugar+ice) layer, as well as loss of flavor and a weak texture. However I wouldn't expect to see this in an accerlerated test. In terms of micro. analysis, this is something that might be worthy of a seperate discussion, as I've struggled with it in the past. Currently we do Total Plate Count (TPC) and Coliform and E.Coli Count (CEC), additionally we send random environmental and product samples to an outside lab for Listeria.

Charles, I'm interested in the shelf life program that you described. Do you have any additional information about it, or could you point me towards somewhere that a similiar program could be derived? I'm fearful that without something to reference such a method, I will not get the support from management to retain that many samples.

Dear Esther,



All I can say is that for the frozen shrimp involved, accelerated testing / micro. analysis was the decisive procedure employed by the receiver in UK. Rightly or wrongly I hv no idea. You may well be correct.

@ ewhite. Sorry for delayed reply. Only today saw yr post.

I agree with Esther regarding choice. It really depends on you/your product what you want to do.

Personally I have used basic organoleptic / microbial analysis similar to yr form for nominal shelf live validations of 12-18 months. IMO yr concept of routine monitoring is only meaningful when part of an overall shelf life program. Regarding sampling, I used six whole cartons taken from successive daily lots over 3 days giving total 18 cartons. Units of each of the 3 lots were then sampled every 3 months and the results compared to internal specifications. This was done for various product types over a staggered time scheme (the storage space required may not be negligible).

I wondered what the microbial test for CEC meant on yr form ? Count E.coli ?

Rgds / Charles.C

[Charles.C]

Dear ewhite,

It was an intra-company methodology but I’m afraid the original source long gone. However I think the basic procedure can be found in various frozen food text books. You’re right about quantity, production / cold storage did squeal but BRC certification is a useful lever. Nonetheless, I daresay, much smaller logistical schemes are in use / acceptable also (???); it also relates to the product sensitivity. I guess this aspect is another incentive for developing accelerated testing where possible.

Rgds / Charles.C

[ewhite]

Charles,

Thanks for the help. I'm still trying to find a happy medium on sampling size. But I think I have the right resources to get something going.

Regards,
Erika