Surface mould cultures for dry sausage

What they are

Surface mould cultures are selected moulds, commonly Penicillium species such as P. nalgiovense, applied to the outside of some dry-fermented sausages so that a white or pale cover grows on the casing as the sausage matures. They are separate from the bacterial starters that acidify the meat and from the staphylococci added for colour and flavour: those work through the meat, while a surface culture works on the casing.

Not every mould-covered sausage uses one. Some dry-fermented sausages are inoculated with selected cultures, and others develop a surface community that varies from batch to batch. Named commercial blends exist, for example Bactoferm MOLD-800, which its manufacturer lists as a mix of Penicillium candidum and P. nalgiovense.

A white surface does not tell you what is growing

Surface colour cannot identify an organism or establish that a product is suitable or safe. The BC Centre for Disease Control guidance on fermented sausage treats mould growth in a food-processing and inspection setting; it is not a household identification test.

A study of French dry-fermented sausages found different fungal communities in commercially inoculated and naturally colonised samples. Those findings belong to the sausages sampled. Work on Penicillium nalgiovense, including its penicillin gene cluster and antibiotic production in cured dry sausages, reports results specific to strains and tests. Species names and surface colour therefore do not support a general safety conclusion.

What is not established

The reviewed sources give no complete household process for choosing, applying or maintaining a surface culture, and this page gives no sausage recipe or application directions. Current manufacturer documents for a named product and strain still need review, and a validated process for a specified sausage needs qualified meat-process review.