Help please! Cheese Packing Question

Hi All,
I'm looking for any information on the obsorbance of CO2 in cheddar cheeses. We flush all pre-pack cheese with 100% CO2 and seem to be getting issues with some packs not snugging/bedding down. Upon inspecting these packs, there seems to be no evidence of failed seals using -750mb vacuum tanks. However when testing the residual oxygen, we still seem to find elevated levels of O2 still present in the packs.
Has anyone else has issues similar to this?
Is there any possibility of the CO2 being obsorbed into the product leaving only O2? Surely this would not increase the O2 level, we have online analysers that alarm and stop if the target goes over our limit of <1%?

BUMP for Quality Cheese.

Some brainstorming:
Is it possible that there are micro leakages in your foil?

Did you change to a new foil supplier?

Has the equipment changed? Is is properly working (how do you check correct working of flushing)?

After what time do you find the levels of O2? In production or after shelf life?

How about microoranisms?

I must admit that in the past i've used nitrogen for gas flushing cheese bags and had no issues.

Caz

Has the equipment changed? Is is properly working (how do you check correct working of flushing)?

Check not just for the flushing equipment but also for the gas measuring devices....

As far as microorganisms are concerned I cant think of any microorganisms in food that will produce oxygen, the typical is to get CO2 or SO2...

Did you check that your CO2 supply is 100% CO2?

Also I have seen that sometimes when the gas mixture (CO2 and/or nitrogen) tank is almost empty you might get a number of paks that contain high levels of oxygen

Thanks for the replies guys... we have online gas analysers that are designed to stop production if the gas flush exceeds the target of <1% O2, we also check the flush with handheld units that show the levels of CO2 & O2.
Some of the retained samples that do not bed down are tested within 5 days using the vacuum tank (-700mb), with no leakers evident and higher levels of O2 when tested using the handheld analysers.
My thinking is that the leaks may be so slight that the CO2 sensor may not be detection the leaking gas?

Could it be the material of your packaging? All kinds of polymer are porous to some extend and O2, CO2 and moisture can enter and leave the pack, depending on the surrounding conditions.

Surrounding air has less than 1% CO2. Thus, if your pack contains 100% CO2, and the polymer of your pack has a poor barrier, then CO2 will exit from the pack to the environment at a rather fast pace to reach equilibrium.

If this theory is sound, then maybe you should get your packaging materials checked out. Perhaps do a COTR to confirm.

If changing another polymer is too expensive, then maybe you can change to N2 instead of CO2. Surrounding air has 78% N2, should take a longer peroid of time for them to escape out of the packaging.

Dear QC,

No idea regarding the practical measurement limitations but as implied in the previous posts, looks like a plot of Conc.(O2) vs time is required for some random samples.

Its called "validation"

Rgds / Charles.C

I must admit that in the past i've used nitrogen for gas flushing cheese bags and had no issues.

Caz

Agreed I would be flushing with Nitrogen.

Regards,

Tony