How is cultured buttermilk made differently from traditional buttermilk?

Traditional buttermilk and cultured buttermilk are distinct products with different origins. Traditional buttermilk is the fluid byproduct remaining after cream is churned into butter.21

In contrast, modern cultured buttermilk is not a byproduct of butter production. Instead, it is intentionally manufactured using skim or low-fat milk through a controlled fermentation process. The production of cultured buttermilk involves the following steps:21

• Pasteurization: The milk is heated to destroy naturally occurring bacteria and denature proteins, which helps prevent the separation of liquid from solids.21
• Inoculation: After cooling, specific starter bacteria—such as Streptococcus lactis—are added to the milk.21
• Fermentation: These organisms convert lactose into lactic acid over 12 to 14 hours, developing the product's characteristic acidity, thickness, and sour flavor.21

While cultured buttermilk is thicker than the traditional version, it is similar in other respects and is often easier for lactose-intolerant individuals to digest.2