Determination of carotenoids in raw and commercial foods: evaluation of cooking and preservation processes on nutraceutical properties

Carotenoids are among the most important and useful antioxidants present in food of plant origin. These compounds can help in maintaining body homeostasis by scavenging oxygen radicals, enhancing the immune system activity and also stimulating cell-to-cell communication: this last process is currently believed to be one of the mechanisms that potentially leads to the development and dissemination of many forms of cancer. Tomato and derived foods, in particular, are rich in carotenoids such as β-carotene, lycopene, lutein, astaxanthin and zeaxanthin. Since tomato is often eaten after cooking, even in the form of sauces and incorporated in complex foods, it is important to evaluate the effect of processing on its carotenoid content. It is also important to understand that cooking is sometimes beneficial, since it can release carotenoids from the original phytocomplexes that often limit their bioavailability. Aim of this study is the development of a reliable 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 separation is achieved in a reversed-phase column, using a methanol-based mobile phase. The characteristic spectrum of carotenoids, recorded by the DAD detector, allows the assessment of possible carotenoid degradation processes, even without modification in chromatographic behaviour. The method is currently undergoing validation, but seems to be suitable for application to raw and cooked tomato-based foodstuffs.