Starter Culture

For most of history a fermented sausage was made by trusting to luck and the resident flora of a particular cellar, or by back-slopping, seeding a new batch with a little of a successful old one. A starter culture replaces that chance with certainty: a defined, food-grade culture of chosen microorganisms, grown up and added deliberately, so the same benign organisms win the same race every time. It is one of the quiet revolutions of twentieth-century charcuterie, turning a craft that could fail unpredictably into a process that can be controlled.

The idea was patented in 1940, when Jensen and Paddock proposed adding lactic bacteria to shorten a sausage's ripening. The craft truly changed, though, in a remarkable coincidence of April 1955, when two researchers, working independently and unaware of one another, published within the same month. In the United States, Niven and Deibel introduced a Pediococcus, then called Pediococcus cerevisiae and now known as Pediococcus acidilactici, for warm-fermented American summer sausage; it reached the market in 1957 as ACCEL. In Finland, Fritz Niinivaara introduced a Micrococcus strain, M-53, isolated from sausage, sold as Bactoferment and in 1966 augmented into the mixed Duploferment. That the two first cultures were so different, a fast acid-making Pediococcus for warm ferments in America, a nitrate-reducing Micrococcus for cool ferments in Europe, is no accident: it is the root of the two traditions. Frozen concentrated cultures followed in the 1970s, and only decades later was it recognised that many of the European micrococci were in fact coagulase-negative staphylococci.

A modern starter is a team, and its members do different jobs. The lactic acid bacteria, chiefly Lactobacillus sakei and curvatus in cool European ferments and the pediococci in warm American ones, ferment sugar to lactic acid, dropping the pH to firm the bind, set the tang and starve out unwanted organisms. The coagulase-negative staphylococci, Staphylococcus xylosus and carnosus, reduce nitrate to nitrite for colour, break down peroxides against rancidity, and build aroma. To these a maker may add surface organisms, the noble mould Penicillium nalgiovense and the yeast Debaryomyces hansenii, for the bloom, the deacidified rind and the depth of a traditional dry sausage. The art is in the pairing and the balance.

In practice a starter is bought freeze-dried or deep-frozen, kept cold until use, then rehydrated in unchlorinated water at room temperature for a short while to wake the organisms before it is mixed evenly and gently through the meat with the sugar it will feed on. Chlorine and heat kill it, and dextrose is its usual fuel. The blend is matched to the plan: a fast, warm, pediococcus-led culture for a quick tangy summer sausage; a slow, cool, lactobacillus-led one for a long-aged European salame; a mould-and-yeast surface culture for the rind. Rate, temperature and humidity follow the supplier's guidance, because a starter delivers its safety and speed only when given the conditions it needs to win.

Its deepest value is safety. By seizing the sugar and the space and driving the pH down fast and predictably, the chosen organisms outcompete and suppress the pathogens, Salmonella, Listeria, Staphylococcus aureus, that a slow or failed spontaneous ferment might let flourish, and many strains add bacteriocins that attack Listeria directly. The classic failure is the sluggish ferment, where too little sugar, too low a temperature or a dead culture lets the pH stall and the pathogens gain: exactly what a live, well-fed, correctly warmed starter exists to prevent.