Critical limits for residual oxygen levels in MAP

Hi,

   I am producing marinated olives and antipasto products in a tray pack, we are using a 30% CO2 70% Nitrogen gas mix. The use of MAP is purely for the aesthetics of the pack ( no concaving of the film lid ) , in testing we achieve 0 - 0.5% residual oxygen which is fine and we are told by our customer that "the standard" is less than 2% but we cannot find a critical limit reference source to quote against even from our customer. Can anyone point me in the right direction.

Thanks

Steve

Hi,

I'm a bit confused by your statement "The use of MAP is purely for the aesthetics of the pack".  I've not worked with the products you describe but for cheese for example, MAP is used to help prolong life but the 30/70 mix is because the carbon dioxide gets absorbed into the cheese which would make a rigid pack like yours concave.  They often therefore use 30/70 to prolong life but also the nitrogen is there for aesthetics.  Are your packs similar?

If excluding oxygen is vital for pack life then <1% or sometimes <0.5% is typical for where mould is a concern.  Where rancidity is your worry, <2% is probably fine.  You're best off determining this by doing some shelf life trials.  If it's to control neither of them, packing in normal air would do the job?

Hi GMO,

     Thanks. Shelf life is established they are fairly robust ingredients the range  been in the market for some time, the products shelf life control points are pH and temp. the customer only wants the product gas flushed to lower the oxygen content obviously but to maintain the film lids appearance so a label may be attached without it being concave. All I'm seeking is a reference point that states that <2% oxygen is acceptable so I can quote it in my manual as a critical limit even though we would achieve the same shelf life with a traditional "vacuum pack " type seal with 20 - 30% air still present

Hi GMO,

     Thanks. Shelf life is established they are fairly robust ingredients the range  been in the market for some time, the products shelf life control points are pH and temp. the customer only wants the product gas flushed to lower the oxygen content obviously but to maintain the film lids appearance so a label may be attached without it being concave. All I'm seeking is a reference point that states that <2% oxygen is acceptable so I can quote it in my manual as a critical limit even though we would achieve the same shelf life with a traditional "vacuum pack " type seal with 20 - 30% air still present

I don't think it's a problem for your manual.  The <2% limit has been requested by your customer for appearance reasons.  I still don't get why it's concave without MAP and not without (does it absorb the oxygen?)  But then it's just a point of recording this is not for food safety or shelf life reasons but simply for your customer's preference on appearance.

If you've just started this though it's worth considering if you increase the risk of anaerobic or facultative anaerobic pathogens, e.g. Listeria monocytogenes or Clostridium botulinum.