IMPACT OF FERMENTATION PROCESS ON COMMON BEAN FLOURS WITH DIFFERENT PROTEIN COMPOSITION

The common bean (Phaseolus vulgaris) represents one of the most important legumes crops worldwide and a key component of the human diet, especially in developing countries. It is a valuable source of high-quality proteins (18–24%), complex carbohydrates (including dietary fiber, starch, and oligosaccharides), essential minerals (iron, zinc, magnesium) and vitamins. The consumption of common beans is associated with several beneficial health effects, including the reduction of cardiovascular diseases, obesity, and type 2 diabetes, as well as the promotion of gut health due to their high fiber and resistant starch content. However, the nutritional potential of beans is limited by the presence of anti-nutritional compounds such as PA, raffinose-family oligosaccharides, lectins, alfa-AI and protease inhibitors. These compounds interfere with nutrient absorption and digestibility. Therefore, the reduction or inactivation of these factors is essential to improve the nutritional quality of beans. Different technological, biological, and genetic strategies have been developed to mitigate these anti-nutritional effects. Technological processes such as soaking, germination, cooking, extrusion, and fermentation effectively decrease PA and raffinose content, enhancing protein digestibility and mineral bioavailability. On the genetic side, a number of mutant lines have been developed: low-PA (lpa), phaseolin-null (phsl⁻) and lacking active lectin (lec⁻), all contributing to enhanced nutritional value and safety. In recent years, common beans have gained increasing interest as functional ingredients in the food industry. They are being incorporated into innovative food formulations such as snacks, breakfast cereals, pasta, and bread, offering opportunities to improve the nutritional profile of foods and support sustainable diet. The purpose of this thesis work was to evaluate the effect of the fermentation process, using different starter cultures, on bean seeds and bean flours in terms of reduction of anti-nutritional compounds (PA and raffinose family oligosaccharide), and to assess the integrity of seed proteins. Two different bean genotypes were used: a control wild-type (wt) line and a mutant line lacking active lectin and phaseolin (lec⁻ phsl⁻). Obtained results showed that in fermented cooked beans, the degree of protein degradation varied depending on the microbial strain used, while in fermented flours, the lower protein content appeared to be balanced by the presence of alfa-AI. The fermentation led to a slight and comparable reduction of PA in both fermented beans and fermented flours. In contrast, the raffinose content exhibited a marked decrease across all fermented samples. The most significant reduction was observed in cooked bean samples fermented with Bacillus coagulans, where the raffinose content decreased by 61% and 81% in wt and lec⁻ - phsl⁻, respectively. Greater reductions were observed in bean flour samples, particularly in the control genotype fermented for 48 hours, with decreases of 93% in uninoculated samples and 86% in inoculated ones. Overall, the results confirm that fermentation is an effective process for reducing anti-nutritional compounds and improving the nutritional quality of common beans.