Oil and Fat Classification by Selected Bands of Near-Infrared Spectroscopy

Abstract

One hundred and four edible oil and fat samples from 18 different sources, either vegetable (Brazil nut, coconut, corn, sunflower, walnut, virgin olive, peanut, palm, canola, soybean, sunflower) or animal (tallow and hydrogenated fish), have been analyzed by high-performance gas chromatography (HPGC) and near-infrared spectroscopy (NIRS). Fatty acids were quantified by HPGC. The near-infrared spectral features of the most noteworthy bands were studied and discussed to design a filter-type NIR instrument. An arborescent structure, based on stepwise linear discriminant analysis (SLDA), was built to classify the samples according to their sources. Seven discriminant functions permitted a successive discrimination of saturated fats, corn, soybean, sunflower, canola, peanut, high oleic sunflower, and virgin olive oils. The discriminant functions were based on the absorbance values, between three and five, from the 1700–1800 and 2100–2400 nm regions. Chemical explanations are given in support of the selected wavelengths. The arborescent structure was then checked with a test set, and 90% of the samples were correctly classified.

The Detection and Quantification of Adulteration in Olive Oil by Near-Infrared Spectroscopy and Chemometrics

“…The assignments for the relevant NIR bands are given in Table 1. 22,26,27 There are very small differences near 5260 cm -1 . These small differences can easily be exploited by multivariate data analysis.…”

Predicting rapeseed oil content with near-infrared spectroscopy

“…Four regions were established to estimate the equation, according to Hourant et al (2000), including regions B (1,300-1,600 nm), C (1,600-1,850 nm), D (1,850-2,050 nm), and E (2,050-2,230 nm). Based on the first derivative, the highest absorption peaks occurred in regions C, D, and F (2,230-2,500 nm).…”

“…Region C contains bands in the spectrum that are characteristic of the first C-H stretching overtones of methylene (CH 2 ), methyl (CH 3 ), and ethenyl (-CH=CH-) groups. Region D contains bands that are characteristic of a combination of C-H stretching bands from ethenyl and OH (hydroxyl) groups in water (Hourant et al, 2000). Despite the presence of Pesq.…”

Quality Evaluation of Olives, Olive Pomace and Olive Oil by Infrared Spectroscopy

“…In fact the application of optical on-line NIR sensor for olive oil characterization is an appealing approach for real-time chemical evaluation, allowing the estimation of acid value, bitter taste (K 255 ) and fatty acids (Marquez et al 2005). Near infrared spectroscopy has been valuable for the assessment of physicochemical parameters of vegetable oils (Sato 1994;Hourant et al 2000;Takamura et al 1995;Franco et al 2006). Infrared spectroscopy (NIR and MID), has also been applied successfully for olive oil evaluation and geographical origin determination using chemometric approaches (Tapp et al 2003;Iñón et al 2003;Galtier et al 2007).…”

“…Analytical methods applied in the examination of chemical composition include the determination of fatty acid profiles by gas liquid chromatography (Firestone et al 1988), high-pressure liquid chromatography (Cortesi 1993;Mariani & Fedeli 1993), pyrolysis mass spectrometry (Goodacre et al 1993), measurement of iodine values and many other determinations. Rapid, non destructive spectroscopic methods such as Raman (Davies et al 2000), ultraviolet (Calapaj et al 1993), MID-IR (Lai et al 1995;Dupuy et al 1996;Guillen & Cabo 1999;Küpper et al 2001) and NIR (Wesley et al 1995;Bewig et al 1994;Sato 1994;Wesley et al 1996;Hourant et al 2000) have all been applied to quantify adulterants in olive oil.…”