Classification of vegetable oils according to their botanical origin using amino acid profiles established by High Performance Liquid Chromatography with UV–vis detection: A first approach

A preliminary study using amino acid profiles to classify oils according to their botanical origin has been performed. Amino acid profiles were obtained from hydrolysis of proteins present in vegetable oils, and established by High Performance Liquid Chromatography (HPLC) with UV–vis detection. Proteins present in hazelnut, corn, soybean, olive, avocado, peanut and grapeseed oils were precipitated with acetone, and the residue was hydrolysed in acid medium. The amino acids obtained were derivatized with o-phthaldialdehyde and separated by HPLC. Peaks corresponding to 18 amino acids were observed using a C18 column and a gradient of acetonitrile–water in the presence of a 5 mM citric/citrate buffer at pH 6.5. The 16 peaks observed in each sample (arginine–serine and phenylalanine–leucine peaks appeared overlapped) were used to construct linear discriminant analysis (LDA) models. Ratios of the peak areas selected by pairs were used as predictors. With a LDA model, the oils were correctly classified with assignment probabilities higher than 99%.