TY - JOUR
T1 - Comparative spectroscopic and rheological studies on crude and purified soluble barley and oat ß-glucan preparations
AU - Mikkelsen, Mette Skau
AU - Jespersen, Birthe P Møller
AU - Møller, Birger Lindberg
AU - Lærke, Helle Nygaard
AU - Larsen, Flemming Hofmann
AU - Engelsen, Søren Balling
PY - 2010/12
Y1 - 2010/12
N2 - The rheology of crude and purified barley (BBG) and oat (OBG) β-glucan samples were characterized. Sample content and major impurities was characterized by Fourier-transform near infrared Raman and infrared (FT-IR) spectroscopy revealing substantial differences between the β-glucan samples. The purification procedure increased the β-glucan content from 66.7 to 82.4% and from 30.1 to 68.4% for BBG and OBG, respectively. Proton nuclear magnetic resonance (1H NMR) analysis was applied to estimate the β-(1→3) to β-(1→4) linkage ratio of the β-glucans. The molar mass of BBG and OBG was determined by high performance size-exclusion chromatography (HPSEC) using β-glucan standards and was found to be 126 and 355kDa, respectively.The viscosity of crude and purified β-glucans was studied at various concentrations (2.5, 5% w/v), temperatures (10-80°C) and shear rates (1-100s-1). BBG was characterized as a low-viscosity β-glucan with Newtonian flow behavior while OBG was characterized as a high-viscosity β-glucan with shear thinning flow behavior. At equivalent β-glucan concentration in solutions the viscosity for OBG was found to be ~100 fold higher than for BBG. A direct viscosity dependence on exact β-glucan content regardless of amount and composition of β-glucan impurities was found for both OBG and BBG. This study suggests that the structural characteristics of the β-glucan polymers such as molar mass are of greater functional importance than the presence of lager amounts of starch/α-dextrins as long as the β-glucan samples are compared at equivalent β-glucan doses.
AB - The rheology of crude and purified barley (BBG) and oat (OBG) β-glucan samples were characterized. Sample content and major impurities was characterized by Fourier-transform near infrared Raman and infrared (FT-IR) spectroscopy revealing substantial differences between the β-glucan samples. The purification procedure increased the β-glucan content from 66.7 to 82.4% and from 30.1 to 68.4% for BBG and OBG, respectively. Proton nuclear magnetic resonance (1H NMR) analysis was applied to estimate the β-(1→3) to β-(1→4) linkage ratio of the β-glucans. The molar mass of BBG and OBG was determined by high performance size-exclusion chromatography (HPSEC) using β-glucan standards and was found to be 126 and 355kDa, respectively.The viscosity of crude and purified β-glucans was studied at various concentrations (2.5, 5% w/v), temperatures (10-80°C) and shear rates (1-100s-1). BBG was characterized as a low-viscosity β-glucan with Newtonian flow behavior while OBG was characterized as a high-viscosity β-glucan with shear thinning flow behavior. At equivalent β-glucan concentration in solutions the viscosity for OBG was found to be ~100 fold higher than for BBG. A direct viscosity dependence on exact β-glucan content regardless of amount and composition of β-glucan impurities was found for both OBG and BBG. This study suggests that the structural characteristics of the β-glucan polymers such as molar mass are of greater functional importance than the presence of lager amounts of starch/α-dextrins as long as the β-glucan samples are compared at equivalent β-glucan doses.
U2 - 10.1016/j.foodres.2010.09.016
DO - 10.1016/j.foodres.2010.09.016
M3 - Journal article
SN - 0963-9969
VL - 43
SP - 2417
EP - 2424
JO - Food Research International
JF - Food Research International
IS - 10
ER -