Olive oil is one of the oil product that is most adulterated by cheap substance such as grease, tallow, and lard. In the other hand, tapered POF is widely used for many sensing applications, particularly for chemical and biosensor. In this paper, the spectroscopy-based tapered POF for detecting lard adulteration in olive oil was investigated experimentally. The taper length and taper waist diameter were varied to evaluate the spectra characteristic of the tapered POF. The samples were made of olive oil adulterated by lard with the concentration of 0 – 5%. The result showed that the changes in taper geometry led the changes in some peaks. The new peaks were introduced at the wavelength of 650, 745, and 930 nm. However, the change of the samples caused the wavelength shifting at the range of 920 – 930 nm. As the lard concentration in olive oil increased, the intensity at the wavelength of 930 nm decreased. Hence, the wavelength of 930 nm is potential to be utilized in intesity-based tapered POF for detecting lard adulteration.
Palm oil is one of common consumed raw food and found adulterated with another materials such as lard. Palm oil adulteration can cause some problems in norms and health. Some methods have been developed in detect lard mixing in foods such as spectroscopy based methods, including infrared spectroscopy and some methods which is complex, expensive, and need of experts. In other side, plastic optical fiber with u-shaped configuration has been developed as biosensors. Through utilization of evanescent field and effect of the change in refractive index to the transmitted power, it has been design a sensor based on plastic optical fiber to detect lard adulteration in palm oil. Experiments show that the most optimal sensor design based on plastic optical fiber with u-shaped configuration is sensor with Infrared LED as light source, 50 mm curvature radius of bend, dan 2 cm length of peeled cladding. From the experiments, sensitivity of the sensor is 0.15630352 μW / % lard concentration.