A bioactive compound is a food component that may have an impact on health. Its bioaccessibility, defined as the fraction released from the food matrix into the gastrointestinal tract during digestion, depends on compound stability, interactions with other food components, and supramolecular organization of food. In this study, the effect of pH on the bioaccessibility of the bioactive dipeptide carnosine was evaluated in two commercial samples of the Italian cured beef meat bresaola at two key points of digestion: before the gastric and after the duodenal phases. The digestion process was simulated using an in vitro static system, whereas capillary zone electrophoresis (CZE) and (1)H nuclear magnetic resonance (NMR) were used for quantitative analysis. The gap between the total carnosine content, measured by CZE, and its free diffusible fraction observable by NMR spectroscopy, was 11 and 19% for two independent bresaola products, where such percentages represent the fraction of carnosine not accessible for intestinal absorption because it was adsorbed to the food matrix dispersed in the digestion fluid.
Keywords: 1H NMR; CZE; bioaccessibility; bioactive compounds; bresaola; carnosine; in vitro digestion.