Application of small-angle scattering to study the effects of moisture content on a native soy protein

Abstract

The nano-and microstructure of glycinin, a soybean protein, has been investigated as a function of moisture for moisture contents between 4 and 21 wt%. Glycinin exhibits peaks in the small-angle region whose positions show minimal change with X-rays for samples up to 13% moisture. However, the use of neutron scattering, and the associated enhancement in contrast, results in the Bragg peaks being well resolved up to higher moisture contents; the associated shift in peak positions between 4 and 21% moisture are consistent with the expansion of a hexagonal unit cell as a function of moisture content. A Porod slope of $À4 indicates that the interface between the 'dry' protein powder and the surrounding medium at a length-scale of at least 3 mm down to $20 nm is smooth and sharp. Scanning electron microscopy indicates that the powders, with low moisture content, have a porous appearance, with the porosity decreasing and microstructure expanding as the moisture content increases.

QUOKKA, the pinhole small-angle neutron scattering instrument at the OPAL Research Reactor, Australia: design, performance, operation and scientific highlights

“…ANSTO conceived and developed the 'Food Science' programme in 2005, since small-angle scattering represents an ideal technique with which to study food -the most ubiquitous form of soft condensed matter (Lopez-Rubio & Gilbert et al, 2012). Over the course of the programme, all macronutrient classes have been investigated, namely carbohydrates, lipids and proteins (Lopez-Sanchez et al, 2016;Martínez-Sanz, Lopez-Sanchez et al, 2015;Bot et al, 2012;Doutch & Gilbert, 2013;Yang, Lin et al, 2016;Kealley, Elcombe et al, 2008;Kealley, Rout et al, 2008;Mata et al, 2011;Salentinig et al, 2014;Phan et al, 2015). Naturally, food is of major industrial significance, particularly as food (and beverage) manufacturing represents the largest industry in Australia by value (Australian Bureau of Statistics, 2012).…”

Morphological Investigation into Starch Bio-Nanocomposites via Synchrotron Radiation and Differential Scanning Calorimetry

“…The measurement time per sample was chosen to eliminate the radiation damage on tested samples, and subsequently determined as 10 seconds. The data reductions of the obtained 2-D X-ray scattering patterns were processed with NIKA macros [15] based on Igor 6.02 (Wavemetrics, Lake Oswego, Oregon). All plots were recorded after the subtraction of instrument background.…”

Dynamics of a globular protein and its hydration water studied by neutron scattering and MD simulations

“…To verify the experimental S(Q) for lysozyme, we calculated it from (1) the crystallographic structure (1AKI.pdb), and (2) an MD simulation at 250 K using a hydrated lysozyme powder model [36,54]. Only S(Q) calculated from MD shows the 4 expected peaks, centered at Q = 7, 14, 30 and 55 nm −1 [20,32], while the shoulder peak A cannot be seen reproduced from the crystallographic structure. Peak B, which should be the measured peak of the structure factor, arises from the order of the secondary structure (β-sheets average distance and α-helix repeat and width), as displayed in Fig.…”