There is no direct relationship between titratable acidity and pH in apple juice, although generally the pH goes up as the acid goes down and vice-versa. The exact relationship differs from sample to sample and depends on esoteric concepts like 'buffering capacity' which will vary for a whole host of reasons. Nevertheless some general empirical relationships may be obtained, and some that I've tabulated are shown below. It must be stressed that they only refer to those fruits growing in those locations at that time. They cannot be held to be exact in other circumstances. A more detailed exploration, with additional data, is given at the end of the page.