In vitro starch digestibility and in vivo glucose response of gelatinized potato starch in the presence of non‐starch polysaccharides

Blending non‐starch polysaccharides with starch is expected to change the rate and extent of starch digestion and has a potential effect on glucose response. The objective of this study was to investigate the effects of four water‐soluble non‐starch polysaccharides: xanthan gum, guar gum, pectin, and konjac‐glucomannan, on in vitro starch digestibility and in vivo glucose response of gelatinized potato starch. Gelatinized potato starch was digested rapidly, and the added polysaccharides significantly reduced the digestion of gelatinized potato starch even over a short reaction time. Postprandial blood glucose response in rats was reduced by the addition of polysaccharides to gelatinized potato starch. The effects on the blood glucose level after ingestion were dependent on the type of polysaccharide. The addition of xanthan gum significantly reduced the blood glucose levels at 30 min, whereas guar gum and pectin reduced the levels at 60 min. The interaction between gelatinized potato amylopectin and polysaccharides was investigated using a quartz crystal microbalance. Xanthan gum was found to be immobilized on the layer of gelatinized amylopectin, suggesting that interaction between starch and xanthan gum is one of the major factors in starch hydrolysis inhibition.