The salami gets its red color during the manufacturing process. The added nitrite curing salt combines the muscle pigment (myoglobin) with the nitrite, resulting in the well-known red color. The process is called reddening.
Ascorbic acid is added so that the salami reddens as quickly as possible. The artificially produced vitamin C serves as an aid. At the same time, it ensures that the sausage retains its red color and the salami has a longer shelf life.