Reboiling DME

[greenxpaddy]

Last week I boiled up my DME for a LONDON ALE yeast starter. I was going to get it started while we were away. Sadly the pouch didn't puff up fast enough and I left the DME in the garage. It was foiled in its pan straight after boiling to stop critters dropping by

6 days later I was hoping to throw in the yeast. To my surprise there were three furry friends floating in my DME! Guessing this to be mould rather than bacteria. I used a teaspoon to pluck them out and throw . Then reboiled the DME for twenty minutes.

Q. Will this have killed all mould and bacteria spores?

Also the DME seemed to have changed in appearance a little even after reboiling - seemed a bit 'grainy'.

Well I have pitched the yeast in now to make the starter - fingers crossed. can't see how the chemical composition can be much different.

On the other hand the yeast I harvested from Erdinger is sat at room temp in a foil covered conical flask without any intruders. Guessing because the yeast have had all the nutrients. Will add some more DME to this one later

[sparky Paul]

The grainy bits are probably where the sugar has burnt or caramelised. The fur coat is most likely infection by a wild yeast.

Boiling will kill most bacteria and/or mould spores, but it may not remove toxins produced by certain particularly nasty bugs. There are also some thermophiles which can withstand boiling, but they are relatively uncommon... however, if they are present, killing competing organisms by boiling allows them to flourish.

Personally, I would have disposed of the malt extract and thoroughly disinfected.