Edible oil forgery is a prominent issue of food production bussiness. In order to lower the production cost and increase the apparent value, some cheap substance is added on the edible oil production and it was mislabelled. Current techniques are able to differentiate each type of edible oils based on its physical characteristics. However, they need special treatment of samples and costly. In this paper, the optical characteristic of absorption of animal-based and plantbased oils are investigated to obtain fingerprints on UV-visible-near infrared wavelength region. Either animal-based or plant-based oils have absorption on wavelength region of 900 – 940 nm. However, each type of oils has unique absorption characteristics on wavelength region of 350 – 700 nm. Hence, the UV-visible region can be used as the marker of each type of edible oils.
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.