Abstract
Crude ${\beta}-glucan$ extracted from Barley was purified by stepwise enzyme treatment (Thermostable ${\alpha}-amylase$, amyloglucosidase, protease). The Intrinsic Viscosity $[{\eta}]$ of the purified ${\beta}-glucan$ was determined by Cannon Fenske Capillary Viscometer (size 50, Cannon Instruments, State, College pa.) at different pH (2, 4, 7, 9, 11) and various salt concentration (0.01 M, 0.03 M, 0.05 M, 0.07 M, 0.1 M and 0.2 M). The $[{\eta}]$ of purified ${\beta}-glucan$ was ranged from $0.997{\sim}2.290\;dl/g$. The $[{\eta}]$ of purified ${\beta}-glucan$ at both alkali, acid condition were lower than those at pH 7. However, the alkali condition of puified ${\beta}-glucan$ solution showed less $[{\eta}]$ than the acid condition of this solution. From 0 M to 0.2 M salt concentration, the $[{\eta}]$ of purified ${\beta}-glucan$ solution was decreased to 0.03 M then increased to 0.05 M NaCl and remained constant to 0.2 M NaCl. The chain stiffness parameter of purified ${\beta}-glucan$ was not affected by temperature from $15^{\circ}C$ to $65^{\circ}C$. The shear rates of various ${\beta}-glucan$ conditions were determined by Bohlin Rheometer (Lund, Sweden). The ${\beta}-glucan$ concentration of 1.0 g/dl and 2.0 g/dl behaved as Newtonian fluid. However, above the concentration of 3.0 g/dl ${\beta}-glucan$ solution, it showed thixotropic and psedoplastic characteristics. Barley ${\beta}-glucan$ appears a damping at 0.5 frequency for the 4.0 g/dl solution. Below 0.5 frequency, it appears a viscous behavior property and above 0.5 frequency, it appears a elastic behavior property.
보리를 thermostable ${\alpha}-amylase$와 amyloglucosidase로 처리하여 ${\beta}-glucan$을 제조하였으며 이를 정제한 후, 보리 ${\beta}-glucan$의 여러가지 리올로지 특성치들을 측정하였다. 본 실험에서 제조한 ${\beta}-glucan$의 함량은 64%이었다. crude한 시료를 정제과정을 통해 순수한 ${\beta}-glucan$을 얻었으며 순수한 ${\beta}-glucan$의 고유점도는 2.290 dl/g 이었다. pH 의존성은 pH 7일 때, 고유점도가 2.290 dl/g로 최대값을 나타냈으며, 산성과 알칼리성이 강할수록 낮은 값을 보였다. 산성보다는 알칼리성이 pH 의존성이 크게 나타났다. 염농도의존성에서는 염을 가하지 않았을 때 보리 ${\beta}-glucan$의 고유점도는 2.290 dl/g이었으나, 염존재하에서는 고유점도가 급격히 감소하는 염농도의존성을 나타냈다. 10% glycerol 용액에서 보리 ${\beta}-glucan$의 고유점도는 1,360 dl/g이었으며 8 M urea 용액에서 고유점도는 4.114 dl/g로 나타났고, urea 제거후의 고유점도는 1.686 dl/g로 낮은 수치를 나타냈다. Chain stiffness는 0.05이었으며 온도에 대해서는 매우 안정하였다. Zero shear specific viscosity에서는 $C{\cdot}[{\eta}]=0.573$이었으며, specific viscosity는 0.327로서 0.573 g/dl농도 이상에서 entanglement가 시작되며, 보리 ${\beta}-glucan$의 농도의존성은 1.0 g/dl, 2.0 g/dl 농도용액에서 newtonian fluid 성질을 나타냈고, 3.0 g/dl 농도 이상일 때는 pseudoplastic behavior를 보여주는 동시에 thixotropic hysteresis가 일어나는 특성을 보였다. Dynamic 성질로서는 4.0 g/dl 용액에서 damping이 0.5 frequency에서 나타나며, 0.5 frequency 이하일 때는 viscous behavior 성질이 있고 0.5 frequency 이상일 때는 elastic behavior 성질을 나타냈다.