A new type of portable sensor is proposed to detect bacterial concentration based on the change in dielectric loss angle δ. The performance of the sensor is tested in four types of drinks, namely, milk, orange juice, peach juice, and tomato juice. Notably, the sensor can detect δ when the bacterial concentration reaches a critical threshold value (approximately 10⁶ cfu mL⁻¹) by applying a 1 V peak-to-peak 200 Hz sinusoidal test signal of 0.25 mA at intervals of 10 min. This work introduces a portable and low-system for rapid detection. The system is a useful tool for microbial screening in industrial and commercial environments.