In your previous thread, you've been told that it can be difficult to prevent the ascorbic acid from decomposing before you analyze it, so the best method will rely on your ability to work quickly.
Titration is a perfectly valid way to quantitate any acid, but it will only give you a useful value if you've removed all other acids, and interfering substances. That can be fairly simple or complicated, depending on the matrix.
There are a number of useful methods for qualifying and quantifying a mixture of organic acids by HPLC, if you have access to the equipment, and the technical experience. If you don't understand that statement, then, you're not ready.
For the best results with the spectrophotometer, you should try to minimize the matrix effects with some sample workup, based on what techniques you can find.