Characterizing deterioration of milk through bioimpedance spectroscopy

Area of Science:

• Food science and technology
• Electrical engineering
• Biomedical engineering

Background:

• Liquid milk quality assessment is crucial for consumer safety and industry standards.
• Electronic sensors offer a non-destructive method for real-time milk analysis.
• Bioimpedance spectroscopy is a promising technique for characterizing biological materials.

Purpose of the Study:

• To develop and validate an electronic sensor-based method for milk quality assessment.
• To characterize milk adulteration using bioimpedance spectroscopy.
• To establish a correlation between bioimpedance parameters and milk spoilage.

Main Methods:

• Fabrication of a cylinder-in-cylinder sample holder for bioimpedance measurements.
• Conducting bioimpedance spectroscopy on raw and pasteurized milk during adulteration at 23°C.
• Modeling milk bioimpedance using the Cole equivalent circuit and extracting parameters.
• Estimating relaxation-time from Cole parameters and performing statistical analysis.

Main Results:

• The developed method successfully discriminated between different brands of liquid milk.
• Relaxation-time showed a monotonic decrease with increasing adulteration time for all milk types.
• Adulteration effects were significant within the first three hours at 23°C.
• A clear correlation was established between relaxation-time and the extent of milk adulteration.

Conclusions:

• Electronic sensor-based bioimpedance spectroscopy is effective for real-time milk quality assessment and adulteration detection.
• Relaxation-time serves as a reliable indicator of milk spoilage.
• Consumption of milk adulterated and kept at 23°C is not advisable after two hours due to significant quality degradation.