Effect of natural flocculants on purity and properties of beta-glucan extracted from barley and oat

In this study, beta-glucan was extracted from wholegrain oat and barley flours by a novel extraction and purification method employing natural flocculants (chitosan, guar gum and gelatin). The use of flocculants decreased the total amount of extracted gum, which was highest in control samples (9.07 and 7.9% for oat and barley, respectively). The beta-glucan specific yield, however, increased with the use of chitosan and guar gum, which were able to remove protein and ash impurities resulting in gums with a higher purity. The highest concentration of chitosan (0.6%) resulted in gums with the highest beta-glucan content (82.0 +/- 0.23 and 79.0 +/- 0.19 for barley and oat, respectively) and highest beta-glucan specific yield (96.9 and 93.3% for oat and barley, respectively). Explanation is in R&D section. The use of gelatin was not successful. All gum samples had a high content of total dietary fiber (> 74%) and a high water holding capacity (4.6-7.4 g/g), but differed in apparent viscosity, which was highest for the oat sample extracted with 0.6% chitosan. This sample also showed the highest beta-glucan molecular weight among the oat samples, which were in general 10-fold higher than for the barley samples. Among the barley samples, beta-glucan molecular weight was highest for the control.