What do you gather about Mr Van Daan’s expertise in the meat and Sausage Business from Anne’s Diary of 10 December 1942.

Mr. van Daan was indeed an expert in the sausage making field. Anne decribes his actions, and the fact he looked like a real butcher.

What with his bloody hands, red face and spotted apron, he looked like a real butcher.

In addition, Anne's description illustrates van Daan's enjoyment of the task.