The dairy industry employs heat coagulation tests (HCT) to assess milk heat stability. The traditional HCT involves heating 1-2 mL of milk to 140°C in an oil bath, lasting 20-30 minutes. Automated alternatives are sought due to the test's time-consuming nature and operator bias. This study proposes using 10 MHz contact and immersion ultrasonic transducers alongside pH and rheological sensors to monitor coagulation in room-temperature skim milk. The ultrasonic wave speed measurements exhibits an inflection point correlating to rheological and pH parameters indicating coagulation during experiments, showcasing the potential of ultrasonics as coagulation sensors in the dairy industry.