Advancing nutritional quality of foods through the assessment of lipid and carbohydrate bioaccessibility

The relationship between diet and health is a central topic in contemporary research, as diet quality plays a key role in chronic-degenerative diseases. While overall dietary patterns are more relevant than individual foods, nutritional evaluation based solely on chemical composition does not reflect nutrient availability. Therefore, bioaccessibility is a key parameter for assessing nutritional impact. This PhD thesis investigated the in vitro bioaccessibility of lipids and carbohydrates in different foods and nutritional supplements, focusing on the influence of food matrix, processing level, and chemical composition, and also explored the biological effects of natural iminosugars and their synthetic derivatives in intestinal cell models. An analytical protocol for lipid bioaccessibility assessment was optimized and applied to four commercial foods with different degrees of processing (shelled walnuts, canned mackerel, spreadable cheese, and biscuits). The results showed that processing significantly affects lipid release and potential absorption, with bioaccessibility decreasing from canned mackerel to spreadable cheese, walnuts, and biscuits. The method was subsequently extended to marine-based dietary supplements (fish oil, krill oil, and Calanus finmarchicus oil), demonstrating that lipid chemical structure (triacylglycerols, phospholipids, and wax esters) and encapsulation form strongly influence n-3 fatty acid bioaccessibility. For carbohydrates, a simplified in vitro digestion protocol was developed by integrating the final enzymatic hydrolysis step into the INFOGEST model, allowing the evaluation of glucose release from starchy foods. This approach showed that dietary fiber reduces glucose release rates, modulating the potential glycemic impact. In parallel, during a research stay at Ghent University, two natural iminosugars and selected synthetic derivatives were investigated in intestinal carcinoma cell lines (Caco-2 and HCT-116) under 2D and 3D culture conditions to assess their effects on cellular metabolism and viability. Overall, this work highlights bioaccessibility as a key determinant of food nutritional value and identifies iminosugars as biologically active compounds with potential health relevance.