Exploring the functional attributes and in vitro starch and protein digestibility of pea flours having a wide range of amylose content.

In this study, ten pea flours covering a broad range of amylose content (37.2-77.6 %, dsb) were characterized for functional and nutritional properties. As the amylose contents increased, the starch contents of the pea flours showed a downward trend (r = -0.990, p < 0.001 in Pearson correlation) but their protein and total dietary fiber contents exhibited an upward trend (r = 0.915, p < 0.001 and r = 0.885, p < 0.001, respectively). A greater amylose content tended to increase starch gelatinization temperatures of the pea flours, which thus required a higher cooking temperature for pasting viscosity development and subsequent gel formation. An increased amylose level reduced in vitro starch digestibility of the cooked pea flours (r = -0.944, p < 0.001) but did not influence in vitro protein digestibility. The insightful findings will be valuable for utilizing the diverse pea lines to create new flour, starch, and protein ingredients.

Rupture of molecular thin films observed in atomic force microscopy. II. Experiment.

In atomic force microscope studies of thin films often a defined jump of the tip through the film is observed once a certain threshold force has been exceeded. In particular, on lipid bilayers this is regularly observed. In a previous paper [H.-J. Butt and V. Franz, Phys. Rev. E 66, 031601 (2002)] we presented two complementary models to describe film rupture. The aim of this study was to verify these models. Experiments were done with solid supported bilayers consisting of dioleoyloxypropyl-trimethylammonium chloride (DOTAP) and dioleoylphosphatidylserine (DOPS) in aqueous solutions and with propanol. Both models describe experimental results adequately. In particular, a narrow distribution of yield forces and an increase of the mean yield force with increasing loading rate is correctly predicted. For the lipid bilayers spreading pressures of roughly 20 mN/m (DOTAP) and 5 mN/m (DOPS) were measured. Line tensions for the edge of a lipid bilayer ranged between 3 (DOTAP) and 6 pN (DOPS).

Equilibrium interaction of solid surfaces across a polymer melt.

Forces across polymer melts are poorly understood despite their importance for adhesion and fabricating composite materials. Using an atomic force microscope (AFM), this interaction was measured for poly(dimethyl siloxane) (PDMS). The structure of the polymer at the surface changed during the first approximately 10 h. Afterward, short-range attractive forces were observed with short-chain PDMS (M(w) = 4200 g/mol). Using PDMS with a molecular weight (M(w) = 18 000 g/mol) above the entanglement limit, we measured a monotonically decaying repulsive force, which indicates that a quasi-immobilized layer had formed at the solid surface. Due to the small radius of curvature of the tip, forces could be measured in equilibrium.