Edible Oils Differentiation Based on the Determination of Fatty Acids Profile and Raman Spectroscopy—A Case Study

Florina-Dorina Covaciu,Ioana Feher,Camelia Berghian-Grosan,Dana Alina Magdas

doi:10.3390/app10238347

Abstract

This study proposes a comparison between two analytical techniques for edible oil classification, namely gas-chromatography equipped with a flame ionization detector (GC-FID), which is an acknowledged technique for fatty acid analysis, and Raman spectroscopy, as a real time noninvasive technique. Due to the complexity of the investigated matrix, we used both methods in connection with chemometrics processing for a quick and valuable evaluation of oils. In addition to this, the possible adulteration of investigated oil varieties (sesame, hemp, walnut, linseed, sea buckthorn) with sunflower oil was also tested. In order to extract the meaningful information from the experimental data set, a supervised chemometric technique, namely linear discriminant analysis (LDA), was applied. Moreover, for possible adulteration detection, an artificial neural network (ANN) was also employed. Based on the results provided by ANN, it was possible to detect the mixture between sea buckthorn and sunflower oil.

Highlights

Vegetable oils are complex mixtures containing a wide range of compounds
Six types of oils—sunflower (SF 1 to SF 4), sesame (SES 5 to SES 8), hemp (HEM 9 to HEM 12), walnut (WAL 13 to WAL 16), linseed (LIN 17 to LIN 20), and sea buckthorn (SB 21 to SB 23)—were chosen for investigation by Raman spectroscopy and Gas Chromatography
The separation, identification, and quantification of the levels of fatty acids in the oils of sunflower, sesame, hemp, walnut, linseed, and sea buckthorn were performed through gas-chromatography equipped with a flame ionization detector (GC-FID) analyses

Summary

Introduction

Vegetable oils are complex mixtures containing a wide range of compounds. They are principally composed of diacylglycerols, triglycerides, and phospholipids (95–98%) and complex mixtures of minor compounds (2–5%) of a wide range of chemical components [1]. Triglycerides are a combination of glycerol and free fatty acids [2]. The composition and abundance of fatty acids and minor constituents present in vegetable oils depend on the plant species from which they were obtained. Within the same species, their composition may vary depending on the agronomic and climatic conditions, fruit or seed quality, the oil extraction process, and refining procedures [3]. Chromatographic techniques are the most common choice in the analysis of the edible oil samples

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