Abstract
The oil industry is in need of rapid analysis techniques to differentiate mixtures of safflower-sunflower oils from pure oils. The current adulteration detection methods are generally cumbersome and detection limits are questionable. The aim of this study was to test the capability of a mid-infrared spectroscopic method to detect the adulteration of sunflower oil with safflower oil compared to fatty acid analysis. Mid-infrared spectra of pure oils and their mixtures at the 10–60% range were obtained at 4000–650 cm-1 wavenumber and fatty acid profiles were determined. Data were analyzed by multivariate statistical analysis techniques. The lowest level of detection was obtained with mid-infrared spectroscopy at 30% while the fatty acid profile could determine adulteration at around 60%. Adulteration levels were predicted successfully using PLS regression analysis of infrared data with R2 (calibration) = 0.96 and R2 (validation) = 0.93. As a rapid and minimum waste generating technique, mid-infrared spectroscopy could be a useful tool for the screening of raw material to detect safflower-sunflower oil mixtures.
Highlights
Adulteration is a major problem for the food industry with significant economical and health consequences as in the case of toxic oil syndrome (Lai et al, 1994)
The palmitic acid content of safflower oil lies between 6.72% and 6.94% while it is between 6.22% and 7.46% in sunflower oil
Adulteration could be detected at levels as low as 10 and 30% with the Orthogonal partial least square-discriminant analysis (OPLS-DA) and soft independent modeling class analogy (SIMCA) of mid-IR spectral data, respectively; while a higher level of adulteration of around 50–60% could be determined with fatty acid analysis data, as confirmed by different chemometric techniques
Summary
Adulteration is a major problem for the food industry with significant economical and health consequences as in the case of toxic oil syndrome (Lai et al, 1994). There are various studies in the literature regarding adulteration detection techniques which focus on fats and oils (Jha et al, 2016; GómezCaravaca et al, 2016; Tena et al, 2015; Ellis et al, 2012). Creative fraud techniques necessitate the development of new adulteration detection methods or the update of existing ones. Safflower oil is mixed with sunflower oil in high proportions since this oil is relatively cheaper. Even small differences between oil prices result in high profits when large amounts of oils are mixed. The oil industry have complaints (personal communication) about the difficulty in detecting the adulteration of sunflower oil with safflower oil even with traditional chemical analysis techniques due to the resemblance in chemical composition (fatty acid, sterol etc.) between safflower oil and sunflower oil (Hurriyet, 2016)
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