Hello Everyone, I am making a wedding cake for a customer and after finishing my practice cake I started to cut it and there are blue spots through out. My cake is a scratch vanilla bean cake recipe, with a thin layer of American vanilla bean butter cream to prevent the filling from soaking in to the cake, and then a home made raspberry filling using raspberries, sugar, water, lemon juice and cornstarch. Any ideas on what would cause this? I have been wracking my brain!...