Extraction of soluble β-glucan from oat and barley fractions: Process efficiency and dispersion stability

This study comprises laboratory-scale extraction of soluble β-glucan (BG) from oat (16 and 32% BG) and barley (12 and 32% BG) fractions, investigation of chemical composition and stability of dispersions prepared from water extracts and techno-economic evaluation for small industrial scale production. Oat and barley fractions were hydrolysed with an enzyme preparation and BG was extracted from hydrolysed samples by boiling water. Enzymatic hydrolysis resulted in medium molecular weight (MW = 38,500–69,400 g/mol) after 2 h incubation with 10 nkat β-glucanase activity/g bran and low MW (11,800–22,600 g/mol) after 4 h incubation with 50 nkat/g bran. MW and concentration of BG affected the stability of dispersions during storage. Barley fractions, after both 2 and 4 h hydrolysis, resulted in higher viscosities than oat fractions. MW of BG in soluble barley fractions was only slightly higher, but the difference in MW does not seem to be adequate to justify the observed viscosity differences. Barley extracts contained higher amounts of starch, however, starch did not have a distinct effect on viscosity. Techno-economic analysis for production process with feedstock design capacity of 100 kg/h showed that production costs varied from 0.06 to 0.11€/g soluble BG. Raw material and capital charge were key cost factors.