I am not sure if the comsol material library contains properties of food. Nevertheless, you can investigate or estimate the properties of the food you want to study and introduce them as a constant. If you property depends on a variable (e.g. temperature) you can introduce them as interpolation functions from a table, as an analytic function or a piecewise function along intervals. The steps are shown in detail here: https://www.youtube.com/watch?v=Q7mnGdgfwtI&ab_channel=COMSOL