Structures of salivary and pancreatic amylase hydrolysates from processed starches

Digestion of starch in humans includes luminal and mucosal steps. Structures from the luminal phase of amylases hydrolysis can impact subsequent steps of digestion at the mucosa of the small intestine. However, structures of the starch digestion products along the gut from the mouth to the small intestines products that impact glucose homeostasis are not well understood. This submission focuses on the luminal step of starch digestion, i.e. impact of salivary and pancreatic amylases on the structure of hydrolysis products obtained from cooked starches from different botanical sources. Starch to water ratios of 1:0.7 (T0.7) or 1:2 (T2) were used to cook normal corn (NCS), wheat (NWS) and potato (NPS) starches. Comparatively, DMSO was used to disperse the starches to remove the effect of granular organisation. Cooked and dispersed starches were then subjected to salivary and pancreatic amylases hydrolysis for 20 min and 120 min. Extent of 20 min hydrolysis was lower at T0.7 compared to T2 and TD for all the starches. The molecular weight profiles of 20 min hydrolysates between the processing treatments were more different for NPS than for the other starches. Oligosaccharide composition of 120 min hydrolysates differed in amounts of DP 2, 3, 5, 6 and 7 between processing treatments and also between the starches. These differences, however, did not necessarily follow the intensity of cooking treatment. These differences in structures of hydrolysates, which are the substrate for mucosal hydrolysis in the small intestine, can potentially influence glucose homeostasis

On scale effect in plates weakened by Rounded V-Notches and subjected to in-plane shear loading

It is now well-known that in plate problems with through-the-thickness cracks in-plane shear and anti-plane loadings generate coupled three-dimensional fracture modes. The dominance domain and intensity of the singular states associated with these 3D fracture modes are functions of the intensity of the primary loading (KII and KIII) and Poisson’s ratio. A similar situation takes place for V-shaped notches. However, for geometrically similar notch geometries subjected the same nominal stress the intensity of the coupled modes is also a function of the plate thickness. Despite this almost all 3D effects are currently ignored in industrial standards and fracture assessment codes. Recent theoretical and numerical studies have demonstrated that in many practical situations the intensities of the coupled fracture modes for cracks and sharp notches are not negligible and can influence fracture conditions. The current paper extends this conclusion to rounded notches. By using the finite element modelling it is demonstrated that the intensity of the stress states associated with the coupled fracture modes in a sufficiently thick plate weakened by a rounded notch can exceed the magnitude of stresses due to the primary loading. This means that the coupled modes can dominate the stress state in the vicinity of the notch root and be primary responsible for fracture initiation.F. Berto, A. Kotousov, P. Lazzarin, L.P. Poo