Isolated potato parenchyma cells: Physico-chemical characteristics and gastro-small intestinal digestion in vitro

Isolated cassava cells: Comparison of structure and physicochemical properties with starch and whole flour

Individual cells are the smallest units of the plant tissue structure, and their structure and physicochemical properties are essential for whole food processing. In this study, cassava cells were isolated using acid-alkali, hydrothermal, and pectinase methods, and the differences in microstructure and physicochemical properties among the cells, starch, and whole flour were investigated. Cassava cells isolated using pectinase showed intact individual cells with a higher isolation rate and less damage to the cell wall structure and intracellular composition. The presence of cell walls in intact individual cells inhibited the swelling and leaching of starch, resulting in a lower peak viscosity and higher gelatinization temperature than those of starch. The intact cell structure and non-starch composition enhanced the shear resistance of the gels in the sample. Heat treatment led to the gelatinization of intracellular starch and increased the permeability of the cell wall, destroying the physical barrier function of the cell wall; however, the compact cell matrix and non-starch components can inhibit starch hydrolysis. This study suggests that cells isolated using pectinase can be used to investigate the effect of cell walls on the functional properties of intracellular starch in cassava. The isolated cells provide new insights into the cassava industry.

Effect of Complexation with Different Molecular Weights of Oat β-Glucan and Sea Buckthorn Flavonoid on the Digestion of Rice Flour

The complex of oat β-glucan (OBG) and flavonoids hampered the digestion of starch-based food and retarded the blood glucose response; however, its effect on gastric emptying and its relative mechanism have not been thoroughly investigated. By using Fourier transform infrared (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), antioxidant ability, and enzymic inhibitory tests for the characterization and in vitro semi-dynamic digestion of complexes of OBG (high and low molecular weights) and sea buckthorn flavonoids, we found that the higher molecular weight complex (FU) exhibited stronger ABTS and DPPH radical scavenging abilities and higher α-glucosidase and α-amylase inhibition rates. Mice fed with rice flour with FU addition exhibited the slowest gastric emptying and intestinal propulsion rates and blood glucose rise and had the lowest activity of digestive enzymes and levels of insulin, ghrelin, motilin (MTL), and relevant gene (ghrelin and GHSR mRNA) expression than those in the control and low-molecular-weight groups. This study provided scientific data for the development of foods with delayed gastric rate and hypoglycemic index for specific populations.

Effect of chewing ability on in vivo oral digestive characteristics and in vitro gastrointestinal starch hydrolysis of three different types of cooked rice

Chewing ability has a strong effect on food digestion. However, little is known about the relationship between the food mastication degree and the subsequent gastric emptying. This study was to explore the effects of individual chewing ability (strong and weak) on the in vivo oral processing characteristics and in vitro dynamic gastrointestinal starch hydrolysis of three types of rice (japonica rice, indica rice and waxy rice). Results showed that the swallowable bolus in the weak chewing group had larger holes and a looser microstructure with more small rice particles, while the strong chewing ones obtained a bolus with higher saliva content (up to 28%) and starch hydrolysis degree (up to 13.55%). Moreover, the gastric retention and starch hydrolysis of the strong chewing ability group were higher in the artificial gastric dynamic system (AGDS). The indica rice particles with the higher degree of fragmentation contacted enzymes easier and hydrolyzed quicker, thus emptying through the stomach faster (81.76%). However, the oral chewing properties of rice mainly influenced the starch digestion in the stomach and the initial stage of the small intestine (∼5 min). This study suggested that the chewing ability and rice variety can influence the bolus properties, which in turn affected the gastric emptying and the degree of starch hydrolysis during digestion.

Comparative study on the structural and in vitro digestion properties of starch within potato parenchyma cells under different cooking methods

To study the effects of cooking methods on the structure and digestion changes of starch encapsulated by cellular structure, intact potato parenchyma cells were successfully isolated and then subjected to different domestic cooking methods, including baking, frying, boiling, and autoclaving. The morphology, crystalline structure, thermal properties, and in vitro starch digestibility of cooked cell samples were investigated. Our results indicated that potato cell walls remained intact and performed as physical barriers preventing the diffusion/absorption of α-amylase to intracellular starch substrates after baking or frying treatment. However, boiling or autoclaving treatment destroyed cell wall structure, and the disrupted cellular structure reduced the digestion rate, likely by inhibiting diffusion of amylase through a weakened cell wall barrier, but could not lower the final digestion extent when compared to the pure starch. These findings suggested that potato products with lower glycemic index can be obtained by baking or frying treatment.