Comparative determination of carotenoids in fresh vegetables, processed products and dietary supplements

Fruits and vegetables constitute the major sources of carotenoid in human diet. They are present as micro- components in fruits and vegetables and are responsible for their yellow, orange and red colors. Carotenoids are thought to be responsible for the beneficial nutraceutical properties some foods in preventing human diseases including cardiovascular diseases, cancer and other chronic diseases and in recent years their antioxidant properties have been the major focus of the scientific research in this field. Tomato and derived foods are rich in carotenoids such as -carotene, lutein, astaxanthin, zeaxanthin and lycopene. Tomato, within the Mediterranean diet is often consumed after cooking, in the form of sauces and included in complex foods, therefore it is important to evaluate the content of such carotenoids as a result of different types of heat treatments, in order to assess any loss due to degradation. Sometimes, the above mentioned treatments may result in an enhancement in the levels of the substances, as these may be released from vegetal phytocomplexes which can limit the bioavailability. Therefore, in addition to defining the varieties of vegetables with the highest levels of carotenoids, it is important to establish the cooking methods and treatments which may allow to maintain food beneficial properties. Aim of this study is the development of an HPLC-DAD method for the analysis of different carotenoids in fresh tomato, in tomato sauces and in sauces subjected to further cooking under different conditions. Carotenoid extraction is achieved by means of a liquid-liquid extraction, followed by a chromatographic separation with a C18 stationary phase, using a methanol-based mobile phase. Furthermore, this method has been applied for the quality control of some tomato-based dietary supplements, in order to compare their properties with those of the fresh tomatoes. The method is currently undergoing validation, but seems to be suitable for application to complex vegetal matrices, such as raw and cooked tomato-based foodstuffs as well as dietary supplements formulations, to test their nutraceutical power.