I’m very aware of the problems that can occur when using unbleached flour in butter cakes, and have a superficial understanding of the mechanisms involved. I’ve recently baked the same cake twice (banana cake) with butter and unbleached SR flour, while the first cake came out with a level top and good crumb the second domed when baking and subsequently sunk, and there was a great gummy strip bordering the base (no surprise!). My question is regarding why the latter result doesn’t occur all of the time; what other variables are likely to tip the balance? In the second cake i used frozen bananas as well as fresh (all fresh in cake #1), could they have released more liquid into the batter and have tip the scales, so to speak? I understand the difficulty in answering this question!

Cheers

Lauren - 14 February 2011 08:16 AM

My question is regarding why the latter result doesn’t occur all of the time; what other variables are likely to tip the balance? In the second cake i used frozen bananas as well as fresh (all fresh in cake #1), could they have released more liquid into the batter and have tip the scales, so to speak?

Isaac Asimov famously said:  the most exciting phrase to hear in science, the one that heralds new discoveries, is not Eureka! (I found it!) but rather, ‘hmm… that’s funny…’”

Your hypothesis about the water content is a good one….how would you test it?  Do fresh bananas really have a higher water content than frozen?  Could you bake one of both until they’re bone dry and compare the difference in weight between the two?  Then could you bake two cakes, one with frozen and one with fresh, but adjust the water content to make them equal?

I will also throw out the idea that the two cakes might have had differing gluten development.  Perhaps the one that collapsed wasn’t mixed as long?  To conduct a good experiment, you’d have to control for this variable, such as using a timer to time the mixing of each cake.

In addition to what Charles said, I would check baking powder/bakking soda.  A cake that domes and then falls sounds like it could be too much leavening.

Thank you for your input and for helping me use that mushy substance residing in my skull

I doubt that the water content in the frozen banana is higher, but i did notice as it was defrosting that it was sitting in a pool of its own liquid (again, not surprising given the effects of freezing that Rose previously highlighted). I didn’t mention that the banana’s were not thoroughly blended into the batter but folded through (with some additional sugar - which absorbs(?) water), and i can only speculate that localising their presence in the batter did not affect the water content in the batter to a significant degree, whereas folding the banana liquid + solid mixture through may have introduced the banana moisture on a more global scale… So, i suppose it’s not so much the water content, but the way it was released by the bananas and blended into the batter (and i have used water, moisture and liquid interchangeably… naughty). I would be experimenting but unfortunately my small family can only eat so much cake, and the Queensland floods have not only limited the supply of bananas but also sent their price through the roof (I’m in Australia)! Unfortunately it’ll be a while before it becomes feasible to start baking with them again :(

Despite that spiel on moisture, i think the flour warrants further examination (hmm, i wonder who influenced my thinking…). I tend to steer clear of unbleached flour in my cakes, and especially SR but on these occasions i had a glut of the stuff in the pantry and was baking from a book written in Aus (where bleached flour is unheard of, though surprisingly, the people i have spoken to believe that all of their flour is bleached!). When i started baking i would use SR as directed in recipes and without fail, all of my pound cakes sunk (though i don’t remember any gumminess) which is a symptom of excessive leavening. Further, when i bake scones (the British type, akin to American biscuits) i use unbleached flour and have found superior rise and texture with SR but an unmistakable metallic taste which i attribute to the leavening, plain flour bakes well in terms of taste but the texture isn’t quite the same (i can get away with SR in pancakes though… hoorah!). [i sense some confirmation bias…] As the flour was taken from the same box on both occasions, it seems odd that the amount of leavening changed dramatically. I suppose another variable is flour taken from the top of the box vs. flour from the middle/bottom of the box… Is it probable that there are higher concentrations of leavening toward the bottom of the box? This is making my head spin! 

Again this is purely speculation, on par with Freudian theory I can imagine a great many experiments to run as there are so many variables at play! Unfortunately though, that won’t happen for a while :( If anyone has made it to this point, you have earned a piece of cake