Milk is a little tricky! I actually work with fruit juices which are more straightforward with this kind of technology. HPP is supposed to be a cold process using no heat. One of the main issues with using HPP on milk is eliminating spores, which can’t be done by high pressures alone. I looked at their patent and it seems they are still using high heat (but lower than pasteurization temps)  in combination with HPP, so it might work!