Cross Contamination

 

This comes up a lot, so I thought I’d try and put some mathematical reasoning down.

To start I’ve just found a typical crumb on my desk. It’s very messy and it’s a gluten-free crumb from a Trufree cracker. I’ve measured it and it’s about 5 mm x 2mm x 1mm. So that is 10 cubic millimetres. This could be the sort of crumb that might get into chocolate from cross-contamination.

As there are a thousand cubic millimetres in a cubic centimetre, then 10 cubic millimetres of water would weigh 0.01 grams. But as biscuit has a specific density of 0.6, then the little crumb weighs 0.006 grams.

So if we take a typical 100 gram bar of Green and Blacks chocolate, then this little crumb would be 60 ppm. Years ago, I found a small screw the size of the crumb in a chocolate bar and I noticed it. Are screws gluten free?

Seriously though, I would suspect that this level would never happen, as manufacturing processes are such, that if say it’s a caramel bar, then they don’t want their mint ones that follow down the line to taste of caramel. And after all there would be a lot of mixing before the chocolate entered the line.

So as somebody who is not supersensitive I would take the chance.

I’ve only ever noticed cross-contamination once and that was with Mint Imperials. I got an Aniseed one in a packet of mint. Both are gluten-free.

And then there’s the story of what happened at Barratt’s in the 1950s or 60s. Their factory was just around the corner from my father’s print works and the story was in all the pubs. A guy was mixing aniseed balls and he had a packet of cigarettes in his top pocket. It fell in and was distributed amongst perhaps a hundred thousand balls. No-one complained.

I shall be writing to Cadburys, as I have issues about Crunchies.