## 1 Introduction
(2020) found that a carbohydrate blocker product (Max Bloc bean protein) containing common bean protein can significantly reduce the digestion of starchy food (like white bread, rice, and pasta) by 69-93% [11]. A diet containing _Phaseolus vulgaris_ extract \(\alpha\)AIs given to healthy human subjects reduced postprandial blood glucose [12], and a diet containing white-kidney-bean-derived \(\alpha\)AIs resulted in moderate postprandial glycemia [3]. [PERSON] et al. reported that \(\alpha\)AI partially purified by ethanol fractionation from white bean can be considered as a raw material for pharmaceutical preparations of \(\alpha\)AIs used to control the levels of glycemia [13]. A purified amylase inhibitor from Mucuna bean (_Mucuna pruriens_) was found to inhibit the activity of human salivary \(\alpha\)-amylase, by which it could play an important role in the management of diabetes-related disorders [14]. A study concluded that an \(\alpha\)AI-active peptide fraction can be found in lima bean (_Phaseolus lmutus_ L.), which is also a promising ingredient for type 2 diabetes treatment [15]. Plant proteins have been found to present high resistance to proteolysis in the gastrointestinal tract due to their specific structural properties [16]. The \(\alpha\)-helix and \(\beta\)-sheet secondary structures of proteins can influence their nutritive value, quality, and digestive behavior. A high percentage of \(\beta\)-sheets may result in low accessibility for gastrointestinal digestion enzymes [17]. The structure of legume seed proteins has been described by a high \(\beta\)-sheet and relatively low \(\alpha\)-helix content. This prevalent \(\beta\)-sheet conformation was found to play a major role in decreasing protein digestibility in legume proteins [18]. [PERSON] et al. (2023) proved the antidiabetic potential of some legumes (green pea, chicken, and navy bean), which increased after gastrointestinal digestion probably due to the generation of bioactive peptides after the hydrolysis of proteins [19]. Investigation of alpha-amylase inhibitors in beans could lead to several new findings and potential applications for science and industry, as these inhibitors have significant biological and health effects. They are new types of natural blood glucose regulators, new options in weight loss treatments, and they even have plant protection potential. Furthermore, they can be used for the development of a new food ingredient. Alpha-amylase inhibitors can be used in functional foods or \"slow-carb\" products that are more slowly digested and have a lower glycemic load. Such products can improve blood glucose control without the need for drug intervention, which may be beneficial in the dietetic food market. Structural and functional studies of the alpha-amylase inhibitor in beans may provide new insights into protein structure-function relationships. These give understanding of how this inhibitor can bind specifically to alpha-amylase, and this information may be important for the design of new synthetic inhibitors or drug molecules. According to the above mentioned, our aim was primarily to assess the in vitro and in vivo digestibility of Hungarian common bean (_Phaseolus vulgaris_)-derived \(\alpha\)AI-1s and common bean meals for their inhibitory activity and, secondly, to monitor the precursor protein of the \(\alpha\)AI-1 during the digestion process. We wondered whether \(\alpha\)AI-1 would remain in the small intestine and, if so, whether it would retain its activity.