Centrally located, Denn's offers fresh pastries and sandwiches from a counter which you can access from inside the store and out on the street. There is a large selection of cheeses and produce. The day I went the produce was underwhelming. But the dairy and non-dairy selections are vast. There is a wall of faux meat products. I selected a 'vegetarian mixed grill' and it was wonderful. It had 2 types of burgers and 4 meatballs on a wooden skewer. All were tasty. They have the typical tofu products in additon they sell tempeh, seitan and faux german meat products. There are aisles of pastas, rices and other grains. Canned and bottled vegetables. Organic products. Everything you find in a regular grocery store, you can find here. They have a large selection of lotions and health care products. I'm sure I'm leaving something out, but I will go there every time I'm in Mainz.
Cons: Produce didn't look fresh, Some items are very expensive