Authenticity of aroma components Enantiomeric separation and compound specific stable isotope analysis

The word “authenticity” is increasingly used in the marketing of food products. A product can be marketed claiming its authenticity such as containing only natural ingredients or originating from a special location produced using local traditional production methods. Within the area of food ingredients a problem with authenticity of aroma compounds has occurred, because natural aromas are wholly or partly replaced with synthetic ones. This is a large economic problem, since natural aromas are often more expensive than artificial ones. Furthermore, the European Union has legal requirements that every product marketed as containing natural flavours should be able to document that the flavours are in fact of natural origin. Such parameters are very difficult to verify because similar aromas often have the same chemical composition regardless of the production method or origin. It is therefore necessary to develop new methods able to verify whether the authenticity of the food products is in agreement with the labelling. Some aroma compounds are chiral, meaning that they can exist as two enantiomers with different spatial orientation. Synthetic aroma compounds will consist of almost equal amounts of both enantiomers contrary to natural aromas where often only one of the enantiomers will be in excess. Consequently, if equal amounts of enantiomers are detected in a food product labelled “Natural” it could be an indication of adulteration. Artificial aroma compounds often have very different ratios of stable carbon isotopes compared to compounds synthesized in plants. Furthermore there can be large variations in isotopic compositions in plants synthesized compounds, since different plants utilize carbon dioxide through various cycles which will be reflected in different fractionations of carbon isotopes. This fact can be used for authenticating aroma compounds. Weather and climate conditions will affect the ratios of stable isotopes of hydrogen in the plants and consequently, differences of stable hydrogen isotopes can ...