Novel technique to detect rancidity of oils using microwave microstrip ring resonator

The present article presents a novel technique to study the rancidity of oils at microwave frequencies through measurements of microwave dielectric properties of liquids, CaCO3 (chalk) was used as a noninteracting medium (matrix) to hold the liquids within and is used to perturb the microwave microstrip ring resonator (MMRR). The rancidified oils exhibit high dielectric constants, giving higher changes in resonoting frequencies. The method is found to be repeatable. Coconut oil (Cocos nucifera), sunflower oil (Helianthus annuus), rancidified coconut oil and rancidified sunflower oil were studied using this technique. The resonant frequency was measured using a scalar network analyzer (SNA, HP 8757C). The method shows noticeable differences in resonating frequency (few tens of MHz) between fresh oil and rancidified oil. (C) 2002 Wiley Periodicals, Inc.