Detection of adulteration in virgin olive oil using a fiber optic long period grating based sensor

摘要

A fiber optic sensing system for the detection of adulteration of virgin olive oil by less expensive sunflower oil is presented. The fundamental principle of detection is the sensitive dependence of the resonance peaks of a long period grating (LPG) on the changes in the refractive index of the environmental medium surrounding the cladding surface of the grating. The performance of the sensor has been tested by monitoring the amplitude changes of the attenuation bands of the LPG in response to variation of adulteration level. With good repeatability, the detection limit of adulteration is 4% and the sensor sensitivity is around 0.07 dB vol%~(-1) of adulterant in the measurement range. The developed sensor is user-friendly, reusable and allows instantaneous measurement of the amount of adulteration without involving any reagents.