We use your Palm Abbe PA201 digital refractometer for making sorbet, and love it! But we’re confused as to how it operates on solutions that contain sugar and alcohol in combination: the readings don’t seem to make sense. Is there a way to compensate for this?
Unfortunately it is not possible to measure sugar contents and alcohol content in combination in a sorbet or other solution using a refractometer. Refractometers are very good at measuring binary solutions (two-part), such as water and sugar, where water is a constant and sugar is a variable. However, a refractometer is not very good for measuring multi-component solutions such as water, sugar, and alcohol. When there are several different components in a solution, such as water, sugar, and alcohol, it is difficult to tell what the contribution is that each component makes to the total refractive index. So, if the refractive index changes, it is impossible to say, with any certainty, which of the component parts changed. A refractometer only measures the total refractive index of a solution and cannot selectively read the refractive index of one particular component. All water soluble fluids look the same to the refractometer. So, depending on the concentrations of the other constituents, it may be difficult to get an accurate reading of any one component.