Rice as natural functional food for a healthy nutrition: characterization, technological aspects and bioaccessibility

The black rice varieties can be considered a sort of natural functional food due to their significant content of polyphenols, especially anthocyanins, and their antioxidant properties. Polyphenols are a huge heterogeneous group of molecules belonging to different chemical classes able to exert a beneficial action on the human organism, which depends not only on their quantity present in the diet, but also on their bioavailability and bioaccessibility. The impact of technological processing, but particularly the impact of cooking mode and digestive process could modify these healthy properties, modulating the bioaccessibility and bioavailability of bioactive compounds. The impact of traditional (boiling, microwaves oven, under pressure pot and risotto preparation) and alternative (pilaf and sous vide) cooking methods on the chemical and nutritional composition of Italian "Artemide" black rice was evaluated, as reported and discussed in Chapters 3 and 4 of this Thesis. In Chapter 5 the impact of the digestive process on the polyphenolic fraction of "Artemide" black rice, subjected to the risotto preparation, is discussed. In general, our results allowed to highlight the main changes in the polyphenolic composition of "Artemide" black rice after cooking and simulated in vitro digestion. The impact on the postprandial glycaemic trend in type 1 diabetic children and adolescents of two different types of rice ("Gigante Vercelli" white rice, and "Artemide" black rice), cooked in different modes (risotto vs boiled), was compared, as reported and discussed in Chapter 6. Finally, as reported in Chapter 7, a faecal in vitro batch fermentation of cooked and digested black and white rice varieties was conducted, in order to evaluate the rice impact on a healthy microbiota, through the quantification via GC-FID of SCFAs (Short Chain Fatty Acids) as desired indicators of the microbiota metabolism. The conclusions and some perspectives of the study were proposed in Chapter 8.