The use of FT-IR spectroscopy in the identification of vegetable oils adulteration

Author: Ersilia Alexa ^1*, Anca Dragomirescu ², Georgeta Pop ¹, Călin Jianu ¹ and Dan Dragoş ²

Received 2 January 2009, accepted 13 April 2009.

Abstract

Expensive high quality vegetable oils and animal fats are susceptible to adulteration. Substitution of high quality and expensive oils and fats with cheaper and inferior quality oils or fats and labeling of those products as pure products are often used by producers to obtain a maximum profit. Such falsification in the oils and fats domain as well as the other food products represents a major economic fraud, and it may have serious implications for public health. The present work intends to identify the adulteration of some olive, peanut, corn germ and pumpkin oils with sunflower oil, the most common oil in Romania, using FT-IR spectroscopy. Experimental results showed that even if the spectral differences in the middle infrared spectral region are very small, because most vegetable oils contain the same type of fatty acids (especially those with C16 and C18) and triglyceride content is similar (C50, C52, C54), nevertheless, there are subtle spectral differences in the spectrum of various types of vegetable oils. This enables us to identify the addition of foreign oil in an oil sample using calibration curves established for certain characteristic frequencies in known mixed oils.

Key words: Olive oil, sunflower oil, peanut oil, corn germ oil, pumpkin oil, FT-IR spectra, adulteration.