134: Testing Oscillating Magnetic Fields to Improve Supercooling Stability During Simulated Storage and Transport

Introduction

Supercooling maintains samples below their freezing points without ice formation, preserving freshness and quality. However, the supercooled state is unstable and prone to disturbances such as mechanical vibrations and temperature fluctuations. OMF at specific intensities and frequencies have shown potential to achieve and maintain supercooled status. This study evaluates the stability of OMF-treated agar gels under external stress conditions that may occur in cold chain logistics.

Methods

Agar gel samples were prepared and supercooled at -5.5 ± 0.5°C under controlled laboratory conditions. Samples treated with an OMF of 12 mT at 5 Hz were compared to untreated controls for supercooling stability over 24 hours. Mechanical stress tests involved orbital vibrations and vertical vibrations with peak forces ranging up to 0.8 g. Thermal stress tests assessed the stability of samples under temperature fluctuations, with ΔT values ranging from 2°C to 8°C. Simulated in-vehicle transportation tests evaluated the impact of road conditions and speeds of a vehicle on supercooling stability.

Results

OMF-treated samples demonstrated a 95% probability of supercooling over 24 hours compared to 10% in untreated controls (n = 50). Stability under orbital vibrations and temperature fluctuations was preserved, although linear vibrations exceeding a peak force of 0.6 g initiated ice nucleation. Power spectral density (PSD) analysis indicated greater vibration energy at higher speeds and on rougher roads, such as coastal and mountainous routes. Ice nucleation was observed at elevated speeds and rough [SJ1] [DL2] surfaces, where vertical vibrations exceeded 0.6 g.

Significance

The study demonstrates that OMF-assisted supercooling significantly enhances the stability of the supercooled state under mechanical and thermal stress conditions and underscores the potential of OMF technology to address challenges in cold chain logistics including storage and transport by prohibiting shock-induced ice nucleation.

Authors: Dongyoung Lee, Soojin Jun