I am making the Red Velvet Cake from Nigella's Kitchen book for my sisters birthday cake. However, I was not able to get the red food colouring paste which she recommends, I could only get the spectral paste concentrate from Sugarflair. How should I adapt the recipe to incorporate it?
For the red velvet cupcakes the red food colour used should be a paste and not the liquid type of food colour as the pastes are much more concentrated. There are a few brands of paste available and the Sugarflair paste is absolutely fine. You do not need to adjust the recipe at all.
In the UK the other brands of paste that can be used are Squires Kitchen and Wilton. Wilton also makes a very good Christmas red paste. All of these can be used in the Red Velvet Cupcake recipe without any adjustment.
Wilton food colours are also distributed internationally and available on-line.