Detection of argan oil adulterated with vegetable oils: new markers

Abstract

RESUMEN Detección de aceite argán adulterado con aceites vegetales: Nuevos marcadores.El objetivo principal de este trabajo es contribuir al control de la autenticidad del aceite argán, un producto marroquí muy valorado. Con el fin de detectar la adulteración del aceite de argán con aceites vegetales comestibles, se han estudiado los siguientes parámetros: ácidos grasos, fracción de hidrocarburos, 3,5-estigmastadieno, ésteres alquí-licos, pigmentos clorofílicos y propiedades físicas como la viscosidad, densidad e índice de refracción. Los resultados de este estudio muestran que el 3,5-estigmastadieno, kaureno y la feofitina-a podrían utilizarse como nuevos marcadores en la detección del aceite de argán adulterado con aceites refinados y aceite oliva virgen al 5%. La composición en ácidos grasos puede emplearse para la detección de la adulteración del aceite de argán a niveles superiores al 10%, debido a la similitud en la composición de los aceites estudiados. Entre las propiedades físicas analizadas, el índice de refracción mostró diferencias significativas entre el aceite de argán y sus mezclas con el aceite de girasol al 10%. PALABRAS CLAVE: Aceite de argán -Aceite de girasol -Aceite de oliva -Adulteración -GC -HPLC. SUMMARY Detection of argan oil adulterated with vegetable oils: new markers.This work aims to contribute to controlling the authenticity of pure argan oil, a valuable Moroccan product. Fatty acids, hydrocarbon fraction, 3,5-stigmastadiene, the alkyl esters of fatty acids, chlorophyllic pigments and physical properties such as viscosity, density and refractive index were studied in order to detect the adulteration of argan oil with edible vegetable oils. The results found in this study show that 3,5-stigmastadiene, kaurene and pheophytin-a can be used as possible new markers for argan oil blends of up to 5% with refined, sunflower and virgin olive oils. Due to the similarity of the fatty acid compositions of the edible oils studied and argan oil, fatty acids can be employed as markers for the detection of argan oil adulteration at levels higher than 10%. Among the physical properties studied, the refractive index shows significant differences for sunflower oil and its blend at 10% with argan oil.

Markers of quality and genuineness of commercial extra virgin sacha inchi oils

“…The oxidative stability was determined following the standard Official Method Cd 12-b-92,18,19 using a Rancimat equipment (743 Rancimat Metrohm Co., Basel, Switzerland), with an air flow of 20 L·h −1 at 100±1 °C (AOCS, 1997) Viscosity and density were measured using a Stabinger SVM 3000 viscometer (Anton Paar GmbH Graz, Austria), and the refractive index was determined with a temperature-controlled Abbe refractometer (Hilger & Watts Ltd., London, U.K.) (Ourrach et al, 2012) The iodine value was determined according to UNE-EN 14111, 2003 …”

“…Before extraction, sacha inchi seeds are partially peeled and cleaned by ventilation to remove impurities, they are then milled mechanically. The oils obtained must comply with the requirements established in the regulations (NTP, 2010;NTP 2014). The specifications of quality and safety are established for all oils of the Plukenetia gender, although some parameters are specific for P. volubilis and P. huayllabambana oils.…”

“…One of its most relevant peculiarities is to be one of the edible oils with the highest content of w3 fatty acids (44.7-55.0% α-linolenic acid (Ln), depending on the ecotype) (Gutiérrez et al, 2011;Maurer et al, 2012;NTP, 2010;NTP 2014;Liua et al, 2014), along with a particular sterol composition (stigmasterol>campesterol), and high amounts of γ-and d-tocopherols (>1900 mg·kg −1 ). Sacha inchi oils are consumed as virgin oils since they have a highly appreciated 'flowered' taste.…”

Selective Methods to Investigate Authenticity and Geographical Origin of Mediterranean Food Products

“…Oussama et al [65] , used Mead InfraRed (MIR) spectroscopy combined with chemometrics for the classification and quantification of argan oil adulteration with sunflower or soybean oils. Whereas, Ourrach et al [66] proposed 3,5stigmastadiene, fatty acids alkyl esters, chlorophyll pigments and hydrocarbons as markers of the adulteration of argan oil with other edible oils. These markers were identified as the result of adulteration studies focused on the phenolic profile of extra virgin argan oil to detect the presence of other vegetable oils [67,68] .…”

Comparative study of three fingerprint analytical approaches based on spectroscopic sensors and chemometrics for the detection and quantification of argan oil adulteration

“…9,10 These practices have been the subject of numerous studies aimed at combating fraud that disrupts the market and deteriorates the positive image of argan oil. These studies can be divided into two general categories: those involving the analysis of chemical compounds in the oil by gas chromatography, 5 high-performance liquid chromatography 11,12 and inductively coupled plasma-optical emission spectrometry; 13 and those based on the combination of spectroscopic techniques with chemometrics tools, such as mid-infrared spectroscopy 10,14 and visible-near infrared. 15 Methods based on the analysis of chemical composition are generally considered time consuming, expensive for routine use in the food industry, require competent personnel and can have a high environmental impact.…”