A method (100) and a system for determining pH values of fermented/acidified animal/vegetable milk products from inline optical measurements, the method comprising: emitting light into a fermented/acidified animal/vegetable milk product (101); optically detecting scattering light coming from said fermented/acidified animal/vegetable milk product, generated from said emitted light once received therein, to collect scattered light data (102); calculating by a computing device including one or more processors running an algorithm at least one value of a variable from the collected scattered light data (103); and obtaining, by said computing device a pH value of the fermented/acidified animal/vegetable milk product by using said at least one calculated value of a variable (104), wherein a single wavelength is used for collecting the scattered light data.