Control of origin of sesame oil from various countries by stable isotope analysis and DNA based markers--a pilot study.

Micha Horacek,Silvia Fluch,Walter Okello-Anyanga,Karin Hansel-Hohl,Gerhard Soja,Kornel Burg,David William Pond

doi:10.1371/journal.pone.0123020

Micha Horacek, Silvia Fluch + Show 5 more

Open Access

https://doi.org/10.1371/journal.pone.0123020

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Journal: PloS one	Publication Date: Apr 1, 2015
Citations: 41	License type: CC BY 4.0

Affiliation: Austrian Institute of Technology, Makerere University

Abstract

The indication of origin of sesame seeds and sesame oil is one of the important factors influencing its price, as it is produced in many regions worldwide and certain provenances are especially sought after. We joined stable carbon and hydrogen isotope analysis with DNA based molecular marker analysis to study their combined potential for the discrimination of different origins of sesame seeds. For the stable carbon and hydrogen isotope data a positive correlation between both isotope parameters was observed, indicating a dominant combined influence of climate and water availability. This enabled discrimination between sesame samples from tropical and subtropical/moderate climatic provenances. Carbon isotope values also showed differences between oil from black and white sesame seeds from identical locations, indicating higher water use efficiency of plants producing black seeds. DNA based markers gave independent evidence for geographic variation as well as provided information on the genetic relatedness of the investigated samples. Depending on the differences in ambient environmental conditions and in the genotypic fingerprint, a combination of both analytical methods is a very powerful tool to assess the declared geographic origin. To our knowledge this is the first paper on food authenticity combining the stable isotope analysis of bio-elements with DNA based markers and their combined statistical analysis.

Highlights

Sesame seed oil is a highly esteemed edible oil that is either consumed as edible oil, or used for pharmaceutical and health purposes
We investigated the applicability of different DNA based molecular marker systems to assess geographic origin of sesame
Carbon isotopes of sesame oil from dark seeds from Egypt range from -29,5 to -29,1‰ VPDB, dark seeds samples from Nicaragua, El Salvador and Bolivia give -29,7, -29,6 and -30,7‰, respectively, always significantly lower than the corresponding oil from white seeds (Table 1)

Summary

Introduction

Sesame seed oil is a highly esteemed edible oil that is either consumed as edible oil, or used for pharmaceutical and health purposes. Sesame (Sesamum indicum L) is a very drought-tolerant plant, partly due to its extensive root system and due to its high temperature tolerance. It is grown in many regions of the world [1]. Control of Origin of Sesame Oil releases the seed, usually the plants are collected before ripening and stored vertically to prevent seed loss when the capsules split. Because of this shattering characteristic accompanied by its indeterminate growth, sesame is cultivated primarily on small plots that are harvested by hand. The discovery of an in-dehiscent (non-shattering) mutant by Langham in 1943 allowed breeding of high yielding, shatter-resistant varieties being used in industrialized countries like the USA [1]

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