Excellent question! Kalona SuperNatural products are low-temp pasteurized to preserve the natural nutritional benefits of our milk. Our milk and most of our dairy products are pasteurized using batch pasteurization (also called vat pasteurization). The milk is slowly heated to 145°F and held at that temperature for 30 minutes. The milk is then rapidly cooled. This method is relatively rare today, and is used mainly by local and regional creameries. The milk in Kalona SuperNatural fluid milk, kefir, buttermilk, butter, sour cream, and yogurt has been batch pasteurized.