Study of effect of sodium alginate on potato starch digestibility during in vitro digestion

• The interaction between food ingredients can affect food properties during digestion.
• Molecular interaction between starch and alginate can reduce the enzymatic action.
• Sodium alginate affects the starch hydrolysis affecting the glucose release.

Foods are complex matrices formed by many compounds whose nutritional properties vary when they are mixed. Therefore, the study of ingredients interactions that occur during food formulation is necessary to understand the final behavior of food during digestion. This study examined the effects of sodium alginate mixed with a starch solution (3.0 g/100 g) on glucose release during in vitro digestion. To evaluate the effect of alginate, three concentrations were used (0.5, 1.0 and 2.0 g/100 g), and the in vitro digestion was carried out in two stages: gastric and intestinal digestion. The glucose release was evaluated by colorimetric. In order to understand the behavior of this mixture, complex index (CI), viscosity analysis and differential scanning calorimetry were performed to study the alginate–starch interaction. The results showed that starch hydrolysis began during intestinal digestion, reaching a hydrolysis percentage of 72% during the first 15 min. A significant reduction in starch hydrolysis was observed when 1.0 and 2.0 g/100 g of sodium alginate was incorporated, with hydrolysis percentages around 55% during the first 15 min. The CI varied from 34.34% to 57.11% when alginate was increased from 0.5 to 2.0 g/100 g. Also, the sodium alginate affected the viscosity which can be attributed to a protector role of alginate on the starch granules that diminishes the swelling and amylose leaching. Through this study it was possible to show the importance of molecular interaction between different ingredients used in food formulation and how these interactions can be relevant in the regulation of the glycemic response in carbohydrate based food.

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