Bioactive Components as Integral Part of Foods and Diet: Evaluation of Effectiveness and Mechanisms of Action

The overall objective of this PhD project was to evaluate the functional properties of different foods (fruits, vegetables and grains) and of their bioactive compounds, trying to highlight the differences existing among plant foods of similar type. Numerous scientific studies have shown that consumption of plant foods can positively affect health and contribute to the prevention of many chronic degenerative and inflammatory diseases. Since it is known that the nutritional value of a food depends not only on the concentration of nutrients and bioactive molecules, but also on their bioaccessibility i.e. the fraction released from the food matrix during the digestive process and potentially bioavailable in the body, all studies described in this thesis have the common characteristic to have evaluated not only the foods themselves, but mainly the products of their in vitro digestion. To study the products of in vitro digestion of foods represent a step ahead in the evaluation of their nutritional value. Three types of plant food have been considering: mandarin juices obtained using different technological treatments; ancient and modern varieties of grains, that were used to make bread; peppers of different varieties. In two studies, the variability of bioactive molecules and their effectiveness were investigated with a combined approach, including the evaluation of their effectiveness in a biological system. The human hepatoma HepG2 cell line was chosen as model system given that the liver is the organ mainly involved in xenobiotic metabolism Overall, studies presented in this PhD thesis allows considering some aspects that are often not considered or underestimated while evaluating the nutritional value of food: 1. The food matrix effect, including its intrinsic variability; 2. The bioavailability of components, and the impact of food processing; 3. The synergism among the different bioactive molecules; the biological response of cells.