Relationships between Swelling Power, Water Solubility and Near-Infrared Spectra in Whole Grain Barley: A Feasibility Study

Starch is the major component of the barley (Hordeum vulgare L) grain (approx. 70 %), and changes in its biophysical properties have an effect on malting and other grain properties. The objectives of this study were to investigate whether swelling properties and water solubility can be determined in whole grain barley samples using NIR spectroscopy and to characterise specific NIR spectra vibration regions that can provide information about these properties. Both swelling and water solubility index were measured in whole grain barley samples by reference methods and using NIR spectroscopy. From the examination of the partial least squares (PLS) loadings, we were able to relate the swelling properties (SP) with wavelengths in the NIR region that can be associated with amylose and amylopectin, while PLS loadings for water solubility index (WSI) were associated with wavelengths in the NIR region related to starch. It was demonstrated that these two parameters can be measured by NIR spectroscopy with standard errors in cross validation of 0.07 g/g and 0.42 % and standard errors of prediction of 0.08 g/g and 0.66 % for SP and WSI, respectively. The use of NIR spectroscopy will allow for the rapid and non-destructive screening of barley germplasm for breeding purposes.