Tin Content Is a Possible Marker to Discriminate Argan Oil Against Olive, Sesame, Mustard, Corn, Peanut, and Sunflower Oils

Abstract

Argan oil occupies an important position in the pharmaceutical, cosmetic, and food domains. Because of its elevated price, argan oil is subjected to adulteration practices by industrial or commercial actors eager to increase profit margins. Therefore, methods to ascertain argan oil authenticity are actively looked for. The use of argan oil elements as authenticity markers has been evaluated. To identify distinctive markers of argan oil allowing the detection of adulteration, the element content of seven pairs of vegetable edible oils is analyzed by inductively coupled plasma atomic emission spectroscopy (ICP‐AES). For each pair, a plant is grown in Morocco and the other in a different country. Content of 12 metals in the resulting vegetable oil is determined and results are interpreted taking into account the soil element content. This study shows that soil element content frequently influences the oil element content but argan oil, which is necessarily prepared from roasted argan kernels, represents a special case since its tin content is much higher than in any other oils. Tin content is a useful marker to characterize argan oil and can be used to certify its authenticity. Practical Application: Tin content determination can be recommended as a possible specific marker to certify argan oil authenticity. This study demonstrates that such analysis is efficient to differentiate argan oil from six other common edible oils. Element content determination is performed over three consecutive years using inductively coupled plasma atomic emission spectroscopy (ICP‐AES) on seven different pairs of edible oils: argan, olive, sesame, mustard, corn, peanut, and sunflower oils. One member of the pair has been prepared from fruit or seeds grown in Morocco while the other one originated from a far removed location. Depending on the type of oil, differences in element content are observed but, remarkably, argan oil is the only oil presenting an elevated tin content that is confirmed by a bibliography search. Therefore tin content determination can be recommended as an additional method to certify argan oil authenticity.

Argan Oil: Chemical Composition, Extraction Process, and Quality Control

“…Spinasterol (34.0-44 g/100 g) and Schotenol (44.0-49 g/100 g) are the major argan oil sterols followed by 7-Avenasterol (4.0-7.0 g/100 g) and stigmasta-8-22-dièn-3β-ol (3.2-5.7 g/100 g) (46) (Table 2; Figure 3). Campesterol is found at a very low level but this is interesting for argan oil authenticity assessment (47,48). This is also rich in squalene, with content much higher than that found in sunflower oil, but is lower than that of the olive oil (49,50).…”

“…As of this writing, argan oil is still being prepared in some sectors of Morocco using mechanical presses, however, in some industrial units and cooperatives, highly efficient, hydraulic presses have replaced endless crews (4). With this process (mechanical or hydraulic process), two types of oil can be obtained: food or cosmetic grade (48). Food argan oil is achieved by cold pressing kernels roasted for a few minutes, whereas cosmetic oil is prepared from unroasted kernels (14,58).…”

Chemical Composition and Optical Properties of Refined Sunflower Oil With Added Various Oils

“…Of the elements to be determined, magnesium is the main one with concentrations of 0.95 -2.95 mg kg -1 for all the studied samples. The concentration of this element (1.18 mg kg -1 ) in RSO is twice lower than that found in Turkish sunflower oil -2.24 mg kg -1 [40]. Magnesium and zinc are the elements whose concentration changes most significantly in the analyzed samples depending on the additive.…”

ICP-OES assisted determination of the metal content of some fruit juices from Yemen's market

“…Trace element content determination is a performant method that has been successfully used to evaluate the quality, as well as safety, of food in general ( Mohammed et al., 2018 , 2019a , 2019b ) and fruit in particular ( Soylak et al., 2013 ).…”