Propionic acid bacteria are commonly used in the production of Alpine cheeses like Emmental and Maasdam, which collectively account for 7 per cent of global cheese production according to Chr. Hansen.
By means of lactate fermentation, the bacteria generate propionic and acetic acid during cheese fermentation. This gives the cheese a characteristically sweet and nutty flavour, while the carbon dioxide generated produces large holes or ‘eyes’.
Chr. Hansen already has propionic cultures in its portfolio that perform this task in Alpine cheese. But now the Danish ingredients supplier is updating its portfolio with a new generation of cultures called PS-20 and PS-40. It said these are “refined and highly concentrated versions” of the older generations.
Explaining the benefits of the new products, marketing manager Anne-Claire Bauquis said they control and standardise the fermentation process, ensuring a consistent cheese flavour.
Bauquis added: “PS-20 and PS-40 effectively provide the typical sourness and sweetness to the cheese in addition to a powerful gas release allowing eye formation. Finally, both new cultures are cost-efficient due to their high concentration and high activity per cell.”
Comparing the two new cultures, Erik Hoear, senior application manager at Chr. Hansen, told DairyReporter.com that they offer slightly different flavour characteristics, with PS-40 giving off a more powerful, broader taste.
As for temperature requirements, PS-20 needs a ripening room temperature over 17°C to grow as it is sensitive to temperatures below 15°C. And PS-40 can grow at a lower temperature but its metabolism is reduced significantly at low storage temperature.
PS-20 and PS-40 Direct Vat Set cultures are available in frozen format in carton sizes suitable for milk vats of 10-20 tonnes. Chr. Hansen said the Direct Vat Set production technology allows the cultures to be added directly to cheese milk without any need for further propagation.