Straight tube Coriolis meters must be better than U-tubes & S-tubes, for your application, considering the apple seeds. Emerson has a straight tube Coriolis meter with titanium (food grade) tubes, which seem to suit your application.
I'm in petrochem, so not very familiar with Chocolates (except that I eat, lavishly!).
Radars should be the right solution, since we use the same technology for Liquid Sulfur levels as well. Guided Wave Radars (Magnetrol / Emerson) would have been a cheaper solution, but then you need to keep...