sugarflair colours disappearing while baking rainbow cake - any advice?

[dylanthedragon]

I'm making a rainbow birthday cake for my niece. I've just baked the red and orange layers using sugarflair colourings but the cakes have completely lost their colour in the oven. The batter was really bright when I put it in.

The last time I made a rainbow cake, I used Dr Oetker paste colours and it worked really we'll. I thought I'd go for the Sugarflair this time as I'd heard they give a brighter colour. But I've now got 2 sad looking brown lumps of sponge! does anyone have any idea what I could be doing wrong? I'm just using a 2 egg all in one sponge mix - following Delia.

Really annoyed because it was great the last time I made it!

cant quite remember but something about cider vinegar mixed with cornflour helps the colour stay. Think I saw it on bbc food website when I made a red velvet cake a couple of months ago but can't remember exactly what I did with it. But if you google red velvet cake on bbc site the recipe tells you why you need it. I found the cider vinegar in m&s

My dh made a rainbow cake but he used a white cake mix where only the egg white is used, not the yolk.

Thanks for the tips. I have decided to get the Dr Oetker colours and try again with them since it's her birthday on Saturday and I don't have a lot if time to try new recipes. I'll definitely look into the vinegar and egg white options for next time.