Structural breakdown of starch‐based foods during gastric digestion and its link to glycemic response: In vivo and in vitro considerations

Abstract

The digestion of starch‐based foods in the small intestine as well as factors affecting their digestibility have been previously investigated and reviewed in detail. Starch digestibility has been studied both in vivo and in vitro, with increasing interest in the use of in vitro models. Although previous in vivo studies have indicated the effect of mastication and gastric digestion on the digestibility of solid starch‐based foods, the physical breakdown of starch‐based foods prior to small intestinal digestion is often less considered. Moreover, gastric digestion has received little attention in the attempt to understand the digestion of solid starch‐based foods in the digestive tract. In this review, the physical breakdown of starch‐based foods in the mouth and stomach, the quantification of these breakdown processes, and their links to physiological outcomes, such as gastric emptying and glycemic response, are discussed. In addition, the physical breakdown aspects related to gastric digestion that need to be considered when developing in vitro–in vivo correlation in starch digestion studies are discussed. The discussion demonstrates that physical breakdown prior to small intestinal digestion, especially during gastric digestion, should not be neglected in understanding the digestion of solid starch‐based foods.

Effect of new type extrusion modification technology on supramolecular structure and in vitro glycemic release characteristics of starches with various estimated glycemic indices

“…According to Liu et al ( 33 ), the differences between samples can be explained by the number of amylose lipid complex, the different degrees of close packing mode of the double-helix structure and double helix orientation within crystal lamellae, leading to various perfect crystallite numbers and sizes of each extrudate. In addition, EPS had a lower Rc but lower digestibility than that of the other starches, possibly because EPS has a larger number of superhelix structure formed by linear amylose and amylopectin compared to that of the other samples ( 27 ). A similar study reported that the Rc of extruded rice starch was 4.4–6.5% ( 33 ).…”

“…EWS had the loosest and most void-distributed granule surfaces. EWS molecules may break more easily during the hydrolysis of amyl-glucosidase and α-amylase than the other samples, whereas EPS showed significant opposite trend ( 27 ). Similarly, Faraj et al ( 18 ) showed that the degree of damage to the extrudate granule morphology of different types of barley flour significantly differed.…”

“…This results in complete destruction of the amylopectin double helix backbone, leading to crystallization of semicrystalline lamella degradation of starch molecules. Hence, raw starch showed weaker resistance to digestion after extrusion ( 27 ). However, ERS and EMS showed lower Mw and Mn but higher resistance to digestion than their native starches.…”

“…Previous studies ( 2 , 27 , 43 ), found that when different types of native starches show distinct amylose values, the hydrogen-bonding forces of the amylopectin branches are significantly different owing to the dissimilar patterns in amylose and amylopectin that are self-assembled by granule-bound starch synthase I or IIa enzymes (GBSSI and SSIIa). Consequently, the higher amylose content of starch resulted in weak intermolecular hydrogen bonding within the side-chains of α-1,4-glycosidic bond of amylopectin than that of the α-1,6-glycosidic bond compared with starch of a lower amylose content ( 43 , 44 ).…”

Effects of pulse crop types and extrusion parameters on the physicochemical properties, in vitro and in vivo starch digestibility of pet foods

“…Prior to the in vitro assay, the extrudates were ground into a fine powder form (Section 2.6), which partly explained the rapid starch hydrolysis rates of the milled samples in the initial 20 min of the enzymatic hydrolysis (Figure 3A and B). However, in the real‐life setting, dogs most likely consume such dry pet foods in a pellet form with limited chewing, the matrix structure of which may play a vital role in determining the starch digestion rate in vivo (Mishra et al., 2012; Nadia et al., 2021). After being chewed to a limited level, in vivo digestion rates of pet food pellets having good integrity may not be as fast as the in vitro enzymatic hydrolysis rates of finely milled samples analyzed in the present study.…”