Determination of Pigments in Virgin and Extra-Virgin Olive Oils: A Comparison between Two Near UV-Vis Spectroscopic Techniques

Abstract

The colour of olive oil is due to the presence of natural pigments belonging to the class of carotenoids, chlorophylls, and their derivatives. These substances, other than being responsible for the colour, an important qualitative feature of the oil, have antioxidant and, more generally, nutraceutical properties and their quantification can be related to the product’s quality and authenticity. In this work, we have quantified the total amount of carotenoids and chlorophylls’ derivatives in several virgin and extra-virgin olive oils produced in Italy, by using two different methods that are based on near-ultraviolet-visible absorption spectroscopy. The first method defines two indexes, K670 and K470, related to absorbance values of oil at wavelengths of 670 and 470 nm, respectively. The second method is based on the mathematical deconvolution of the whole absorption spectrum of the oil to obtain the concentrations of four main pigments present in olive oils: β-carotene, lutein, pheophytin A, and pheophytin B. The concentrations of the total carotenoids and total chlorophylls’ derivatives, as obtained by the two spectroscopic methods, are compared and the results are discussed in view of the practical usefulness of spectroscopic techniques for a fast determination of pigments in olive oil.

Simultaneous Determination of Pigments, Tocopherols, and Squalene in Greek Olive Oils: A Study of the Influence of Cultivation and Oil-Production Parameters

“…Squalene was also detected in high concentrations. All of the compounds' average concentrations were similar to olive oil samples produced in Italy or Spain [1,15,21,22]. A great number of samples presented very high concentrations of carotenoids.…”

“…Olive oil is a significant and very beneficial ingredient of the Mediterranean diet. Extra Virgin Olive Oil is obtained from the olive fruits of Olea Europaea L. trees, by mechanical extraction processes under controlled temperature conditions, which result in the preservation of its quality characteristics and bioactive compounds [1]. Olive oil has been produced since ancient years and has always been a very healthy and nutritious component of the human diet, mainly because of the very rich and pure bioactive content.…”

First Study on the Oxidative Stability and Elemental Analysis of Babassu (Attalea speciosa) Edible Oil Produced in Brazil Using a Domestic Extraction Machine

“…The first range included the presence of unsaturated fatty acids including oleic and linoleic acids, whose peak around 280 nm was much more intense than those of the other components [49]. Besides, the second spectral ranges observed between 350 and 450 nm, as presented in the inset of Figure 5 corresponds to chlorophylls or carotenoids [50,51].…”

Application of Infrared Spectroscopy for Functional Compounds Evaluation in Olive Oil: A Current Snapshot

“…Besides a good prediction of fatty acid ethyl ester and wax, Uncu et al [113] quantified lutein, pheophytin A, and their derivatives and total xanthophylls by FTIR + UV/vis with a range of R 2 cv of 0.71-0.85, R 2 pred of 0.70-0.84, and RPD = 1.5-2.5 values but the prediction of the rest of the pigments were poor (R 2 cv = 0.60-0.76, R 2 pred : 0.42-0.62, and RPD = 1.2-1.5). Along the same line, Borello and Domenici [114] compared two near-UV/vis spectroscopic techniques for the determination of pigments, i.e., total carotenoids, and total chlorophyll derivatives in virgin and extra-virgin olive oils. Although UV/vis spectroscopy is very tempting for analysing the pigments, NIR and MIR spectroscopy typically gives a more specific molecular fingerprint of oil.…”