The Dorset Dairy Co says
Cultured cream is double cream that has gone through a fermentation process during which the live bacteria have converted the milk sugars into lactic acid. Aroma compounds are produced, creating the distinctive fuller, richer flavour of cultured cream. The process also naturally thickens the cream leaving it stiff and spoonable.
Fermentation does not just provide a great depth of flavour, it also breaks down the milk protein, casein, which can be difficult to digest.
Our cream is very similar to Crème Fraîche and it has a mild tanginess which works very well in both sweet and savoury cooking. The tangy flavour can enhance many dishes and the high fat content will prevent the cream from curdling when added to hot soups or sauces.