Effects of boiling and roasting on proximate composition, lipid oxidation, fatty acid profile and mineral content of two sesame varieties commercialized and consumed in Far-North Region of Cameroon.

The aim of this study was to determine the effect of boiling and roasting on the proximate, lipid oxidation, fatty acid profile and mineral content of two sesame seeds varieties. The proximate composition was significantly affected (P<0.05) during treatments. The minerals of seeds roasting at 120°C for 10min were significantly decreased. The free fatty acids content of sesame oil after processing was significantly increased (P<0.05). Iodine and peroxide value were also affected by processing. Totox and p-Anisidine values were significantly increased during processing. The fatty acids composition a little modified during processing, and roasting at 180°C for 10min mostly affected the polyunsaturated fatty acids for all sesame varieties. C16:0, C18:0, C18:1 and C18:2 were quantitatively the most important fatty acids in sesame oil. Boiling appeared to be the best processing method for cooking the two sesame varieties concerning oxidative stability and fatty acid profile.

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

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.