Add the lemon and lime zests, the lemon and lime extracts, and the citric acid, and whisk everything in. When everything is whisked together, the mixture should have a thickened texture that holds the tracks of the whisk for a few seconds. It should not be thin like milk, but sometimes, depending on the white chocolate used, the truffle mixture takes a little bit of finessing to get it to emulsify properly. If it is thin after you whisk everything together, continue to let it come to room temperature and whisk occasionally as it cools. You can speed up the cooling process by putting it in the refrigerator and whisking after 4-5 minutes, until it changes from a thin liquid to a thicker truffle mixture.