Effect of mechanical properties on in vitro dynamic digestion of starch contained in hydrogels

Background

This study evaluated the effect of mechanical properties on the in vitro dynamic gastrointestinal digestion of hydrogels containing starch (HCSs) as a model for studying the nutrient digestibility of solid foods and provide a useful theoretical basis for the processing of specific foods.

Result

Four types of HCSs with two‐level of fracture stress (17.4–20.9 kPa, 55.5–57.6 kPa) and two‐level of fracture strain (25.4%–28.5%, 53.7%–57.4%) were prepared. For these HCSs, gastric disintegration degree of hydrogels reduced significantly when fracture strain exceeded 30% (p < 0.05). Simultaneously, gastric emptying of HCS particles was affected by mechanical properties, e.g., even at the same level of fracture stress (ca. 20 kPa), the dry solids retention ratio markedly decreased from 0.90 to 0.43 with a decreasing of fracture strain from 53.7% to 25.4% (p < 0.05). For the starch hydrolysis of HCSs after gastric digestion, more than 70% starch in the particles of all types of HCSs emptied did not undergo digestion. The starch hydrolysis of HCSs during small intestinal digestion was also influenced by their mechanical properties. Fracture strain of HCSs affected starch digestibility in hydrogels rather than their fracture stress.

Conclusion

The gastric disintegration, the gastric emptying and the starch hydrolysis of HCSs are suppressed when fracture strain exceeded 30%. Even with the amount of nutritional components contained in hydrogels being the same, the in vitro gastrointestinal digestion behavior of HCSs depends on their mechanical properties, providing the potential to be used for the design of processed foods with controlled bioaccessibility.

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