Was it very warm when you put them in there? air expands when it is warm, maybe when it went in the freezer it shrunk as the air got cold. I'm no expert though, it was just a thought.

Hey.I'm not an expert either, so I don't know why the air would've collasped ... but I think that reason that no mould grew etc. was because there was no air. If the pack was tightly sealed like you said then no air would've been able to get in ... so no oxygen and hence - no life.=]Sabrina.

Yeasts break sugars down to water and carbon dioxide,consuming oxygen and in the process making some unintended hydrogenperoxide, which must be removed using catalase. The hydrogen peroxide is broken down bythe catalase in yeast, in this reaction: 2 HOOH --gt; 2 H2O + O2I#39;m no chemist but I believe all this rearrangement of the molecules by the yeast causes the pressure from the gases in the package to be less than what it was when the product was first packaged. Hence a partial vacuum develops in the package and it appears vacuum-packed.

PV=nRT

Hmmm a really interesting one, as this is unlike anything I have seen if my Food Science classes at Universiteit Stellenbosch....While the yeast reactivity is one plausible hypothesis (it certainly sounds good on the surface), there's no way to prove it short of opening the package and seeing if there is whiff of alcohol to go with it. And three of the components namely E500 aka Sodium Bicarb indicate that there's can't be very much yeast in there, as the bicarb was needed to raise the crumpets. Also, this means the yeast is dead - they are baked before being placed in the package, and it would literally take 6 months for them to grow, and most yeasts, particularly the classic Saccharomyces sensu stricto used in baking tends not enjoy being cold. So that rules that one out.No, in this case - I would give my professional opinion that there is a chemical, rather than biochemical reaction going on in there, and the most likely culprits are a possible interaction between the cations of Sodium Bicarb (E500), Calcium Propionate (E430), and Salt...and I suspect also there was a little bit too much water in the mix, allowing a fair degree of mixing. The subtraction of gas due to cooling is likely also to be a gas-density effect, made worse by chemical generation of a small amount of peroxide radicals. Some physical interaction is also experienced by the film coating the crumpets - I have also had lots of food using Saran/Polyethylene wrapping (like your crumpets have got) also going through a shrink, and they definitely did not have any yeast or peroxides in them. Polyethylene, in thin films is farily tempt sensitive in the low end (this from my Food Machine Engineering course, those steam tables were hard!), and shrinks quite a lot....Thats my very best guess - a bit of microbial fun maybe (open and smell), alternatively some enthusiastic chemical reaction (if there was too much water and they got pally with each other - strange stuff happens!), or else - the packaging has wierd ideas, I've seen it lots of times before this.