My mother always told me not to play with my food, but I often find myself unable to resist. Having contemplated it for a while, and then been spurred on by the discussion in the comments, I decided to have a go at a ‘real’ sour-dough cake, that is one raised using yeast alone, not self raising flour or baking powder.

I’ve done it twice now, with good results, the first time using a carrot cake recipe which worked brilliantly. I made up the mix as usual, except I substituted plain flour for self-raising, threw all the ingredients in and gave it a good stir, and then I left it in the mixing bowl for the yeast in the sour dough to do its thing. My kitchen is usually cool, and it was October, but after a couple of hours it was still nicely bubbly, not quite like a freshly fed Herman but with bubbles clearly visible on the surface. Now it’s these bubble that are important, the more bubbles the more the cake will rise. For those of you who know how yeast makes baking rise, skip the next bit!

For those of you who don’t, the yeast uses the sugar as a food source, and gives off CO2 as it ferments, which is what the bubbles are. These bubbles expand in the baking process and make the cake rise upwards, as due to the confines of the tin it’s the only way it can go.

I was really pleased with the carrot cake. After a couple of hours to rise, similar to bread making, I poured it very carefully into a lined tin so as not to disturb the bubbles, then baked it in the oven and watched it rise. The finished texture was lovely and everyone enjoyed it. It was so successful I decided to do it again!

For my second cake I chose lemon, poppy seed and white chocolate, and only after I’d mixed the batter did it occur to me this might be too acid for the yeast to be happy. I decided to leave it anyway, but after an hour the surface was still beautifully smooth – not a bubble in sight! This left me with a dilemma, but there were several options in this situation;

  1. add more Herman, and so more yeast, to speed up the rise.
  2. add more sugar to feed the yeast and thus speed up the rise
  3. move to a warmer place to give the more energy and speed up the rise.
  4. cheat and put in a teaspoonful of baking powder

After I’d added half a cup more Herman and left it another hour I had bubbles!

Again, with bubbles covering the surface I poured it very carefully into the tin and baked for another really successful cake.
Whilst I was having my play and pondering the length of time to leave the cake, I came to the conclusion at least 2 hours seems necessary but the longer the better (unless it’s a really sweet batter in a really warm room, then you might have a problem!).

I also had a sudden brain wave and it occurred to me that as I have a programmable oven I could make my batter in the morning and leave my Herman to rise in a lined tin in the oven, then the oven would turn on, bake it for 40 minutes and I could come back to fresh cake! Genius!

Go on, give it a go, let your Herman do what nature intended, I promise you won’t regret it.

by Elspeth Barraclough