Sterols as a biomarker in tracing niger and sesame seeds oils adulterated with palm oil

Tesfaye Deme; Gulelat D Haki; Nigussie Retta; Ashagrie Woldegiorgis; Mulatu Geleta; Hinsta Mateos; Paul A Lewandowski

doi:10.1016/j.heliyon.2021.e06797

Sterols as a biomarker in tracing niger and sesame seeds oils adulterated with palm oil

Heliyon. 2021 Apr 16;7(4):e06797. doi: 10.1016/j.heliyon.2021.e06797. eCollection 2021 Apr.

Authors

Tesfaye Deme^{1

2}, Gulelat D Haki³, Nigussie Retta¹, Ashagrie Woldegiorgis¹, Mulatu Geleta⁴, Hinsta Mateos⁵, Paul A Lewandowski⁵

Affiliations

¹ Center for Food Science and Nutrition, College of Natural Sciences, Addis Ababa University, P. O. Box 1176, Ethiopia.
² Department of Food Science and Applied Nutrition, Addis Ababa Science and Technology University, P. O. Box 16417, Addis Ababa, Ethiopia.
³ Department of Food Science and Technology, Botswana College of Agriculture, Private Bag 0027, Botswana.
⁴ Department of Plant Breeding, Swedish University of Agricultural Sciences, Box 101, SE-230 53, Alnarp, Sweden.
⁵ School of Medicine, Deakin University, Geelong, Victoria, 3216, Australia.

Abstract

Food adulteration is a serious social problem all over the world. The oil obtained from the niger and sesame is known for its quality and has a high market value in Ethiopia. The cost of the oil obtained from these oilseed crops is high unlike other plant oils, thus prone to be mixed with other cheap oils to increase profits. The study aimed to quantify the sterol profile of niger seed and sesame oils thereby trace adulteration of these oils with palm oil. Gas Chromatography coupled to Mass Spectrometry was used to analyze the sterol fractions of oils. A blend of palm oil, at a level of 10%, with niger seed and sesame oil was prepared. In all the studied oils; sitosterol (467.2-2778.96 mg/kg), campesterol (295.9-869.85 mg/kg) and stigmasterol (125.6-920 mg/kg) were the dominant sterols identified. Lupeol, Lanosterol, and Olean-12-en-3-one were only identified in a significant proportion for niger seed oil. Moreover, cholestroltrimethyl silyl ether (19.9 mg/kg) and 24-Nor-22,23- methylenecholest-5-en-3β-ol trimethylsilyl (TMS) ethers (139.14 mg/kg) were only identified in palm oil and used to trace adulteration. An attempt made to trace these compounds by mixing palm oil at a level of 10% with niger seed and sesame oils was successfully detected its presence. Hence, as the physicochemical properties of oils can be arranged to cover adulteration, marker identification provides a reliable identity of the specific oil.

Keywords: Adulteration; Biomarker; GC-MS; Niger seed oil; Sesame oil; Sterols.