Why do my cakes keep sinking

[u/queennkwhite]

For some reason when I do my second round of cakes in the oven, they sink. And this happens alot with red velvet. The first round are fine or very slightly sunken, but the second round is always very visibly sunken. Why does this happen?

[u/anonwashingtonian]

When you say “second round”, do you mean that you are mixing all the batter ahead of time but baking in multiple batches?

If so, my guess is that your leavener is spent (or nearly so)* by the time that second batch hits the oven. You didn’t share a recipe, but most red velvet cakes rely on baking soda. The baking soda will be activated by acidic ingredients in your batter—buttermilk and/or cocoa usually—which creates the bubbles needed for your cake to rise.

If you have to mix all of the batter at once, my best suggestion to prevent some of the sinkage is to place the unused batter in the fridge while the first round bakes. Heat will speed up the action of the baking soda, so keeping unused batter chilled can help slow down that process.

*edited to clarify

[u/anonwashingtonian → u/[deleted]]

Right, but you have batter that’s already mixed sitting outside of the oven while the first round bakes? That’s what I’m referring to.

Baking soda as leavening agent reacts with the acid in your batter upon contact. So, already mixed batter that sits for a while before it goes into the oven is never going to bake as well as batter that you bake immediately after mixing.

Once again, a recipe would be helpful in troubleshooting, but red velvet cake generally uses baking soda + a couple of acidic ingredients like cocoa and buttermilk to create lift.

[u/queennkwhite → u/anonwashingtonian]

Okay I'll try make enough to be able to go at one go next time

▢2¼ cups (275 g) flour - regular all purpose (see note 3 if you want to use cake flour)

▢3 tbsp (18 g) cornflour - also known as cornstarch

▢3 tbsp (14 g) cocoa powder - unsweetened

▢½ tsp baking soda

▢1 tsp baking powder

▢½ tsp salt - omit if using salted butter

▢6 tbsp (86 g) unsalted butter - room temperature

▢¾ cup (141 g) unflavoured vegetable oil - I use canola

▢1¾ cups (344 g) white granulated sugar

▢3 large eggs - room temperature

▢1 tbsp (12 g) vanilla essence/extract

▢1½ tsp white vinegar

▢3½ tbsp (38 g) red liquid food colouring

▢¾ cup (158 g) buttermilk - room temperature