Establishment of analytical methods for the determination of new foodprocessed contaminants

The development of sensitive analytical methods has allowed identifying non- nutrient chemicals in food that may affect the human health and are recognised as food chemical contaminants. Some of these compounds are originated from food processing and several studies have demonstrated that can induce tumours in animals. Process- induced food carcinogens are defined as those undesirable chemicals unintentionally present in food as a result of processing and/or preparation of the raw material. The discovery of acrylamide in processed carbohydrate rich food in 2002 sparked renewed interest on some other known food carcinogens such as volatile N-nitrosamines (VNAs) and has also led to the discovery of some others that were previously unknown like furan. Furan and volatile N-nitrosamines (VNAs) are induced food toxicants and due to their potential harmful effects on human health, they have been classified as probable and/or possible carcinogens to humans by the International Agency for Research on Cancer (IARC). At present, food processing technologies able to prevent their formation are not available. To guarantee food safety, identification and quantification of food contaminants as well as the evaluation of their occurrence and risk assessment are needed. An indispensable prerequisite to fulfil these objectives is to have available reliable analytical methodologies. The analysis of furan and volatile N-nitrosamines is challenging due to their physicochemical properties, relatively low concentration levels and the complexity of the food matrices and therefore, there is interest to explore new analytical methodologies able to enhance sensitivity, selectivity, adaptability and also to meet the criteria of European Commission (2002/657/EC) regarding the validation and establishing the performance of analytical methods. In this context, this thesis was conducted to study furan and volatile N- nitrosamines as process-induced food toxicants from the development of analytical methodologies to the evaluation of their presence in food and risk assessment estimation for Spanish population. A fully automated headspace solid-phase microextraction (HS- SPME) gas chromatography coupled to ion-trap mass spectrometry (GC-ITMS) methods to evaluate the presence of these contaminants in food products and to estimate the real exposure of the population to these compounds were established. Parameters affecting the HS-SPME performance including extraction and desorption conditions were experimentally optimised in order to obtain the maximum extraction efficiencies. In addition, GC-ITMS methods using electron ionization and full scan MS mode for furan analysis and selected reaction monitoring tandem mass spectrometry with chemical ionization (CI-IT MS/MS) for VNAs analysis were developed. The experimental results are presented in three scientific papers, two devoted to furan determination and one to the analysis of volatile N-nitrosamines. The applicability of both HS-SPME-GC-MS methods for the determination of furan and VNAs has been demonstrated analysing several selected foods commercialised in Spain. Furan was detected in all samples at concentrations, being baby food and coffee the products with the highest furan content. In contrast, VNAs were not detected in any of the analysed beer samples at concentrations levels above limits of quantification, and the presence of VNAs (NDMA and NPYR) were only found in 3 out of 18 processed meat product samples analysed indicating the effectiveness of the measures adopted by the manufactures to avoid the formation of VNAs. Therefore, a survey on furan content in coffee brews and baby foods was conducted while this study was not performed for VNA because of the low frequency and levels found in the samples analysed in this thesis. The presence of furan in coffee and baby food categories constitutes a potential risk for human health because they contain high furan content and are highly consumed. The evaluation of furan levels found in these food products are included in two scientific articles. In addition, the effect food preparation, heating and handling, on furan content and an estimation of risk assessment of furan intake from food consumption are also included.En los últimos años, la presencia de compuestos químicos tóxicos y cancerígenos que se forman a partir del procesamiento de los alimentos ha suscitado un creciente interés debido a los efectos nocivos que pueden provocar en la salud de los organismos vivos. Dentro de este grupo de compuestos se encuentran el furano y las N-nitrosaminas volátiles, que han sido clasificados como posibles y/o probables cancerígenos en humanos por la Agencia Internacional de Investigación del Cáncer (IARC) y cuya presencia ha sido confirmada en los alimentos procesados. En esta tesis se han establecido métodos analíticos basados en el uso de la microextracción en fase sólida y la cromatografía de gases acoplada a espectrometría de masas para la determinación de estos contaminantes. Después de validar los métodos analíticos se ha determinado la presencia de estos compuestos en alimentos comercializados en el mercado Español para evaluar el riesgo que supone para la población. Así mismo, se ha estudiado los parámetros que influyen en la generación de estos tóxicos en alimento durante el procesamiento y se ha recomendado practiques y procedimientos para disminuir sus presencia en los alimentos