The two most common materials applied to avoid growth of unwanted mold are natamycin and potassium sorbate，sorbate or natamycin helps to inhibit mold growth during the final stages of drying, but mold growth can also be inhibited simply by having the proper climatic conditions in place.

The two common ways of preventing growth of unwanted mold is to apply natamycin or potassium sorbate to the salami. However, it is best to avoid growth of unwanted mold during the initial stages of fermentation in the first place, mainly by controlling the level of RH during all stages of fermentation and drying and applying smoke at the correct time. Growth of unwanted mold can be fought successfully using natamycin, an antifungal produced by Streptomyces natalensis. Natamycin forms a complex with the steroids found in molds and yeasts and destroys their cell membrane. As a result, permeable cell membranes permit cations and other ions to penetrate into the mold cell, making its pH drop rapidly and ultimately, the cell dies. A major advantage of natamycin,  compared with potassium sorbate, is that it does not penetrate the sausage mass at all and therefore has no impact on fermentation, color, or flavor development, especially in the outer layers of the product. Steroids are not present in bacteria, which means that natamycin has no impact whatsoever on the bacteria present in salami. It has no impact on the starter cultures added and the entire fermentation process is not influenced in any way. There are a few products on the market containing natamycin. In most cases 5–7 g of a commercial product is mixed with 1 L of warm water, well stirred, and then left standing for around 30 minutes. During this time the mixture will thicken slightly. Around 8–10% of salt is added afterward and this final mixture can be sprayed onto the salami or the freshly filled salami can be dipped once into this low-viscosity slurry. Experience shows that natamycin is several times more effective than potassium sorbate.

Another option to avoid growth of unwanted mold is to apply potassium sorbate. The filled salami can be either dipped right after filling in a 3–4% potassium sorbate solution or the filled salami can be sprayed with this solution 1–2 days after fermentations has commenced. Most commonly, the filled salami is dipped into the solution for a few seconds and spraying is not commonly practiced. Several food standards in the world have a set maximum level of residual sorbate within the outer layers of raw fermented salami and the strength and duration of the dipping solution as well as the actual dipping process has to be adjusted so maximum levels in the finished product. The disadvantage of using sorbate is that it penetrates into the outer layers of the salami and can interfere with fermentation and cause discoloration. Another method applied to reduce growth of unwanted mold is to add 1–2% of potassium sorbate into the soaking solution, which casings are placed into before being filled.