Root cause and solution for sporadic complaints of mould with MAP bread

Hi everyone! We are getting sporadic complaints of mould with some MAP bread (nitrogen/carbon dioxide 50:50) and are scratching our heads as to its source? Have any of you had this before, and if so, how did you resolve it? Many thanks, Simon

Good Morning Simon,

How are you verifying your headspace?

What does your leaker test look like?

What's the airline cleaning frequency?

Hi

The most likely problem is your residual oxygen level is too high

Two possible reasons

You are not removing the atmosphere to the extent that you think

Your packs are leaking

the leaks can be very small - pin holes in the seam

or you can get traces of product that prevent the seal being effective

You need something like an Oxybaby gas analyser to check the residual O2

A QAD leak check is to imerse the pack in a water bath and push slightly looking for air bubble

rgds

Pinholes in bags is common in grated pizza cheese and that is where it starts.  They are typically very robust plastic but it doesn't take much to allow growth.

Thanks everyone for your responses. This is great!

You can also achieve better shelf life if you alter the ratio of carbon dioxide to nitrogen in favour of carbon dioxide, because the carbon dioxide dissolves into the product to produce carboxylic acid – which lowers the pH and inhibits micro growth.

A lot of people will use a mixture of nitrogen and carbon dioxide because if you go for 100% CO2 you can get package collapse. A flow-wrapped package can look like it’s been heat-shrink’d and that’s not always appealing on the shelf. If you look at cheese in modified atmosphere, the bag often looks like it’s had all the air sucked out of it and that’s the visual effect you can run into.

I’ve used modified atmosphere for ciabatta bread products and the package collapse wasn’t an issue for us, so we went with 100% carbon dioxide.

The other thing you can look at is environmental hygiene between heat treatment (baking) and packing, because any contamination from raw flour etc between those processes can mean you’re putting microbiologically active product into the package, and yeast will grow anaerobically quite happily. One of the first things I’d want to do is get some air plates into your production environment to see if you’ve got airborne micro that could be getting onto the bread while it’s cooling and before it’s packed.

One thing that hasn’t been addressed above, make sure to give the packages time to cool down before you do your seal integrity tests. If you take a flow-wrapped bag immediately from the packaging line and put it under water, a lot of the time the seal will burst just because it hasn’t had time to cool. The slightest little bit of pressure will be enough to rupture the package. You should test the internal atmosphere for a selection of packages immediately after packaging (there will be gas exchange between the product and the internal package atmosphere over time, so this test needs to be immediate) but tests for seal integrity should wait 5 minutes so the bag seal has chance to strengthen after heat crimping.

Hope this helps