Bubbles On Top Of Baked Cake - Slightly Sunken

Decorating By mylittlemod Updated 16 Mar 2013 , 9:32pm by mcaulir

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mylittlemod Posted 25 Mar 2012 , 9:32pm
post #1 of 15

Hi, can anyone offer me some advice as to why my mud cakes have a crust of bubbles in the centre on top after baking? It sinks ever so slightly and just means I have to level off a little more but otherwise the cake is perfect.

I am using the Planet Cake chocolate mud cake recipe in an 8 inch square pan as recommended. Cooking time is 1 hour 40 mins in a 160 degree oven. I put the cake on the middle shelf and don't open the door until the time is up. The cake is cooked all the way through although probably a little more moist just under those bubbles.

I noticed when I made the cake in a round tin slightly smaller than the recommended 9 inches for the recipe the cake rose beautifully and had no bubbles.

When I mix the chocolate sauce and egg/oil/buttermilk mixture into the dry ingredients bubbles form. I mix slowly with a large spoon as the recipe suggests so I can't be over mixing. I have tapped the tin on the counter so air bubbles can rise up and out but many remain on the surface. Should this happen? I have attached a photo.

14 replies
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step0nmi Posted 25 Mar 2012 , 9:48pm
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i am not sure where you are located...but this seems like a very long time to bake a cake and at that low of a temperature. the cake does look like it's a normal baking texture to the outsides but that middle leads me to believe it's not. but, i am thinking it's because the cake baked too slowly. maybe someone else has thoughts on it?

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CSIMisty Posted 26 Mar 2012 , 1:24am
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I'm guessing the long time baking time is because of the low temperature. You mentioned that you tap the pans on the counter before putting them into the oven? Have you tried popping the bubbles you say remain? Does the center come out clean when you insert a toothpick?

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mylittlemod Posted 26 Mar 2012 , 2:02am
post #4 of 15

Hi, I am in Sydney Australia. I am following the instructions from the cook book so adhering to their cooking times and temperature. The skewer comes out clean when I test it at the end of the cooking time. Thanks for your help!

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mylittlemod Posted 26 Mar 2012 , 2:09am
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I should add that I am baking 4 of these it was on the third one I have tapped the tin on the counter to let air bubbles rise frustrated after the first two bubbled up. I did pop the bigger ones (which were still very small) but the rest are very tiny and it would be impossible to pop all of those. The recipe uses bicarb of soda and I am guessing this is what gives it the bubbles? The recipe uses 125 g or self raising and 125 g of all purpose so there is a raising agent in the SR flour but not sure missing out the bicarb will work. This is a well known cook book so I can only trust they have the forumla right!

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step0nmi Posted 26 Mar 2012 , 2:12am
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ok ...I guess you are doing Celsius then, which makes sense. I still feel that is way to long of a baking time and yes, your toothpick would come out clean because it's fully baked. this may be over baked? have you tested the cake and it's still moist? a great way to tell if a cake is done baking is by lightly touching the top of the dome that forms and if your imprint pops right back up, it's done! Or slight separation from the edge of the pan tells you the cake is done.

i think that bubbles when mixing is not that bad of a thing...like you said, you do the tapping of the pan on the counter to make them rise to the top. if you are talking about the DOME when baking this is fine also because then you know all your ingredients are activating and baking correctly icon_smile.gif a little more detail on what you are needing to know about the baking process would be helpful. Other than that...I dunno! :p

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kmstreepey Posted 26 Mar 2012 , 2:27am
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I know exactly what you are talking about because it has happened to me with a chocolate cake recipe I was developing. It is like a mud cake, though I'm not entirely sure that matters. Once baked, the middle of the top would have a crust that was like bubbles had risen and set there. Is that what you have?

In any case, I'm still not entirely sure why that happens, but I do not believe that it has to do with baking time or temperature. I did end up adjusting the baking soda level from 1/2 teaspoon to 1/4 teaspoon and it no longer had the crusty bubbles. I should mention that my recipe contains both baking powder and baking soda, so when I reduced the baking soda, I also raised the amount of baking powder accordingly to make sure I had enough leavening.

My cake also took a very long time to set (an hour for an 8X3 round at 350) before the adjustment was made. I have some more research to do on it, but I suspect it has to do with the acidity of the batter as well as the leavening agent (type and amount).

I hope that helps!

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mylittlemod Posted 26 Mar 2012 , 3:03am
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Thank you everyone. KMStreepey what you describe sounds exactly the same. A crust of bubbles centre top of the baked cake.

I have skimmed off the top of one of my cakes (only by a few mms roughly 1/4") and the centre seems fine just below the surface so I guess maybe I am worrying about nothing! The outer crust tasted moist and very nice. I will be layering these cakes and slicing up to form a 3d cake so it's probably not a problem. I was just curious as to why this may be happening. My recipe calls for a 1/2 teaspoon of bicarb and although I am usually as accurate as can be, in my haste I am levelling it off on the side of the tub and not with a knife so maybe even a fraction more than required is causing this.

I have attached another pic of the cake with the top skimmed. It was straight from the fridge so difficult to cut but other than a faint square where the bubbles were it seems fine (I didn't want to trim it further as I won't be using them for another day or two).

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step0nmi Posted 26 Mar 2012 , 3:16am
post #9 of 15

i'm sorry...but something does NOT look right to me there. icon_sad.gif i don't know if it was just the color of the lighting, but i would say it looks as if the middle of your cake is not cooked correctly still. so sorry...i hope someone else can help with this!

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mylittlemod Posted 26 Mar 2012 , 3:43am
post #10 of 15

Eeeek! Now I am worried. I do think however the lighting isn't doing it justice (old iPhone no flash!). As the cake was very cold straight from the fridge the knife 'grazed' the chocolate across the top as it was really too firm to cut and the section where the bubbles were shows up a little more grazed. The skewer came out clean and it shrank in from the sides so fingers crossed everything is as it should be!! Thanks.

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kmstreepey Posted 26 Mar 2012 , 1:27pm
post #11 of 15

I think it looks fine. The lighter part is probably just the edge of where those crusty bubbles were. I always used my cakes (after trimming the crusty part off) and they were fine. Actually, very moist (but totally cooked through) and chocolate-y. I think you are totally fine using that one.

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Dayti Posted 26 Mar 2012 , 1:39pm
post #12 of 15

Mud cakes are usually very liquid in batter form so they do need longer baking time and lower temp, so you are definitely doing the right thing. I have baked a fair few mud cakes in my time (using both dark and white chocolate) and the bubbles on the surface and the crusty top (and sides) are normal. If you are trimming the top to level it you have nothing to worry about. One way of making it less crusty and therefore easier to trim is to brush boiling water on the top as soon as you take it out of the oven - very hot water on very hot cake. Then immediately cover the cake in the tin with plastic wrap. This traps all the moisture in and makes the top less crusty. I read this on CC because I was also worried about it. So don't worry, you are doing everything right icon_wink.gif

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mylittlemod Posted 27 Mar 2012 , 3:01am
post #13 of 15

Thank you for your comments. I am feeling a little happier now! I've got one more to bake and will put them all together on Wed/Thurs to build up my hawaiian shirt cake. Thanks for the tip re boiling water too. Sounds good!

Thank you

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ApplegumPam Posted 16 Mar 2013 , 9:06pm
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There is loads of sugar in this recipe and if it isn't dissolved properly you can end up with these bubbles - and the crunchy top

I cook mudcakes on a regular basis (not PC recipe though) and I think the answer lies in homemake baking strips - wet paper towel encased in alfoil wrapped around teh sides of cake and secured with a bulldog clip -  and a loose piece of foil sitting over the top of the tin - sitting on your lining sheets which extend above the sides of the tin - you can scrunch the corners slightly (like the Aussie handkie hat! LOL)  -  this TENTING helps to protect the surface of your cake and also the baking strips helps to get a nice level cake -   remember this will ADD time to your baking time - mudcakes do well at LOW & SLOW cooking - sometimes I will bake a larger mudcake for 6 hours!

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mcaulir Posted 16 Mar 2013 , 9:32pm
post #15 of 15

Looks fine to me. That'swhat the inside of my mud cakes look like.

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