What is the main factor that gives cream a tangy flavor?

The tangy flavor in cream primarily comes from the presence of additional live bacteria that produce lactic acid. When cream is cultured with specific bacterial cultures, these bacteria ferment the lactose present in the cream. This fermentation process converts lactose into lactic acid, which lends a distinct tart or tangy flavor to the cream.

This is especially true for products like sour cream or crème fraîche, where the intentional addition of these live bacteria is what differentiates them from regular cream. The fermentation process can enhance the flavor complexity and add a pleasing acidity that balances the richness of the fat in the cream.

In contrast, high-fat content, the pasteurization process, and fermentation in general could influence the flavor profile but not to the degree or specificity that additional live bacteria does. The high-fat content contributes more to the creaminess and mouthfeel rather than the tanginess. Pasteurization is primarily a safety measure that eliminates harmful bacteria and does not contribute to the tangy flavor. While fermentation does play a role, the key element here is the specific introduction and activity of live bacteria that turn cream into products with that distinctive tang.