I am working on a project at the moment, whereby the scenario is a yeast problem in a cake factory. A proportion of cakes produced are producing bubbles under the sugar paste, which appear to be due to yeasts.
Does anyone have any insight into what might cause this type of problem, ie could it be linked to raw materials? Or equipment? I have spent many an hour trawling the internet but can't come up with anything useful.
Many thanks in advance
Pops
Dear Pops,
Although I am not an expert on this matter, but I hope I can give you some hint.
As you know, when yeast consume and metabolize sugar, they produce ethanol and CO2, which causing bubbles. It was a common reaction in bread industry, and I am sure you know it better. Just for comparison, I found some interesting informations on the net:
http://www.botham.co...bread/yeast.htmThe primary function of yeast is to supply carbon dioxide gas which inflates the dough during proof and the early stages of baking (oven spring).
Carbon dioxide cannot form a gas bubble on its own it requires a 'nucleating site' (i.e. somewhere it can gather to form a bubble). In fizzy drinks microscopic projections on the side of the bottle provide those sites which is why when you release the pressure as you open the bottle you see 'streams' of gas running from the sides. In bread dough the nucleating sites are provided by the nitrogen gas bubbles trapped in the dough during mixing. The oxygen from the air having been used up by the yeast.
During proof stages the carbon dioxide goes into solution until the solution is saturated and then any more which is generated makes its way into the nitrogen gas bubbles which grow in size and the dough expands. The more yeast and the warmer the temperature the faster the expansion - we get oven spring because the maximum gassing rate occurs at 40-45C.
From the link above, I quoted some informations which sayin' that the expansion increase when the temperature increase. So lowering the temperature perhaps may solve your case. Or... is it possible to dissipate the Nitrogen out of the dough? So the 'nucleating site' won't be formed?
If the temperature and Nitrogen issue won't work, maybe you can change the sugar. Sucrose is very best for making foam, and glucose didn't make the yeast have the most foaming. As for the rest, you can read it on this link:
http://www-saps.plan...ords/rec358.htmAnd it always been a ritual for me to asking Mr. Wiki when I have some problem. Here Mr. Wiki goes:
http://en.wikipedia.org/wiki/YeastOn that link, it said that yeast will die on high temperature. A bit contrary if compared with the first link (Botham's Educational Page), IMO. But probably, what mentioned in the first link is the temperature will trigger the expansion, meanwhile the yeast had long gone...
Mr. Wiki also give us some advice on choosing the type of yeast, maybe it can helps you out:
http://en.wikipedia.org/wiki/Baker's_yeastLast but not least, I found this remarkable literature about CO2 production during the growth of yeast. Its very interesting, although I dont know it might be useful for you or no:
http://www.plantphys...int/7/1/139.pdfWell, that's all I can do for now. I am willing to have a further discussion 'bout this matter
Regards,
Arya