## 4 Discussion  
This study investigated the impact of different polyphenols on the digestibility of various starches (wheat, rice, potato, and maize) when added before and after gelatinization. Epigallocatechin gallate was consistently the most effective in reducing RDS, TS, and (eGI) across all starch types (mostly in the dose of 20 mg). It was also the most efficient in terms of SDS and SDI in some cases. Kaempfer, naringenin, hesperidin, quercetin, and _trans_-ferulic acid were effective for specific starch types, with variations depending on whether they were added before or after gelatinization. The highest RS content was observed with different polyphenols across various starch types. From a nutritional point of view, starch is classified into rapidly digestible starch (RDS), slowly digestible starch (SDS), and resistant starch (RS) [41]. RDS is the quantity of starch that is transformed into the constituent glucose molecules within 20 min following the initiation of enzyme digestion. RDS undergoes rapid digestion and absorption in the small intestine, resulting in a prompt increase in blood glucose levels. It was documented that considerable fluctuations in blood glucose levels can exert significant stress on the regulatory mechanisms of glucose homeostasis. Such stress can, in turn, give rise to adverse consequences at the cellular, tissue, and/or organ level and finally lead to obesity, insulin resistance, and diabetes [42; 43; 44]. SDS is the amount of starch that is converted into its constituent glucose molecules within 120 min of enzymatic digestion. It is slowly digested throughout the small intestine to provide a sustained release of glucose with a low initial blood glucose level. The potential health benefits of SDS include improvements in glucose metabolism, diabetes management, cognitive performance, and appetite control [42; 43]. In regard to the impact of SDS on glucose metabolism, it is demonstrated that its consumption results in markedly slower and diminished fluctuations in blood glucose, insulin, and non-esterified fatty acids (NEFAs) in comparison to RDS. Additionally, this is accompanied by lower levels of circulating triacylglyceredrols and apolipoprotein B-100 and B-48 in triacylglycerol-rich lipoproteins. Furthermore, SDS is demonstrated to induce an elevation in glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) levels during the late postprandial phase [45; 46; 47; 48]. The third kind of starch nutritional fraction is resistant starch (RS). It is not digested in the small intestine; instead, it is fermented by gut bacteria in the colon, resulting in the production of short-chain fatty acids (SCFAs). It is a dietary fiber, and its consumption is linked to many health benefits [42; 43; 49]. As food remains in the small intestine for approximately 4 h [50], total starch (TS) is the sum of starch digested during this period and RS. The starch digestion index (SDI) is a ratio of RDS and TS. Finally, the glycemic index (GI) is a measure that quantifies the rate of increase in blood glucose levels in response to the consumption of carbohydrate foods. Foods can be classified into three categories according to their GI values: low GI (\(\leq\)55), middle GI (56-69), and high GI (\(\geq\)70) foods [10; 51]. The majority of starch foods have a glycemic index value greater than 70 (e.g., white/whole wheat bread, white rice, boiled potatoes, and cornflakes) [9; 52]. According to the literature, the optimal amount of polyphenols is 10 mg per day. This amount corresponds to the recommended daily intake of five portions of fruit and vegetables [53]. Doses twice and half the optimal amount, 20 mg and 5 mg, respectively, were also tested. In the case of starch, the following were also tested: wheat starch (a basic ingredient in bread making), maize starch (the most popular in the world), potato starch (the most popular in Poland), and rice starch (the most popular in Asian countries), so that the research would have a global scope.