193: Developing a Radio-Frequency Identification (RFID)-Based Sensor for Improving Food Quality and Safety: A Study on Milk Freshness Detection

Introduction

Poor cold chain impacts the shelf-life of packaged pasteurized milk as temperature abuse can accelerate bacterial growth and deteriorate milk quality and safety. It cannot be detected from outside and the product may become unacceptable long before its "use-by" date. Existing detection methods are destructive. Therefore, a non-invasive technology is required to address this issue. Wireless sensing technology using RFID can detect packaged milk quality in real-time and alert users for its freshness status. In this study, we have developed a RFID-based gas sensor to monitor the milk spoilage through sensing of microbial volatiles.

Methods

Marker VOCs during microbial spoilage of pasteurized milk at different temperatures were identified using gas chromatography-mass spectrometry (GC-MS) and correlated with microbial load. A passive high-frequency RFID tag was converted into a gas sensor by drop-casting poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) as the sensing polymer. A single-turn loop-coil antenna connected to a vector network analyzer captured RF signals from the modified tag. The sensor was exposed to varying concentrations of marker VOCs, and its response was monitored to evaluate the detection capability.

Results

We found acetone as a marker volatile produced during microbial spoilage of pasteurized milk. Freshly stored milk (0 days) had acetone concentration of 1 ppm and increased to 6.01, 5.48, and 5.81 ppm at the end of microbial shelf-life when stored at 10°C, 20°C, and 37°C, respectively. Therefore, it can be stated that acetone is produced with a maximum concentration of 6 ppm during the microbial spoilage of milk irrespective of storage temperature studied.

The unmodified RFID tag had a resonant frequency of 13.62 MHz in the presence of air. After the modification as sensor, the tag had resonant frequency of 13.82 MHz. Preliminary study showed a frequency shift of 50 KHz once exposed to 40 ppm acetone gas, resulting in resonant frequency of 13.817 MHz. Such a high frequency shift indicates the potential of developed RFID sensor to detect acetone.

Significance

The developed sensor could offer a reliable and efficient solution for non-invasively monitoring of milk spoilage in real time, which can help to reduce waste and ensure the safety of milk products for consumers.

Authors: Mr. Abhinandan Pal and Dr. Kanishka Bhunia