보리로부터 분리한 ${\beta}-Glucan$의 이화학적 특성

Physicochemical Characteristics of ${\beta}-Glucan$ Isolated from Barley

찰성(waxy) 및 메성(non-waxy) 보리로 부터 ${\beta}-glucan$을 분리, 정제하였고 정제한 ${\beta}-glucan$의 표면구조, DSC특성, 고유점도를 비교하였으며 ${\beta}-glucan$의 첨가가 보리전분의 호화특성에 미치는 영향을 조사하였다. 보리의 총 ${\beta}-glucan$ 함량은 찰성보리가 6.5%, 메성보리가 5.3%였다. 알칼리 추출 후 1차 정제한 crude ${\beta}-glucan$의 ${\beta}-glucan$ 함량은 찰성보리가 62.9%, 메성보리가 59.2%였으며, 수율은 찰성보리가 5.54%로 메성보리의 수율 3.34%보다 높았다. 2차 정제한 ${\beta}-glucan$의 수율도 찰성이 4.46%로 메성의 2.59%보다 높았다. SEM으로 관찰한 정제 ${\beta}-glucan$의 표면구조는 섬유상의 fibril들이 서로 얽힌 망상의 배열을 이루고 있었다. DSC로 측정한 융점은 찰성보리 ${\beta}-glucan$이 $184.6^{\circ}C$로 메성의 $180.3^{\circ}C$ 보다 높았고 겔화에 의한 상전이는 $68^{\circ}C$와 $84^{\circ}C$ 부근에서 2개의 흡열피크로 나타났으며 찰성 ${\beta}-glucan$의 엔탈피 값이 작았다 정제한 ${\beta}-glucan$의 고유점도는 메성보리보다 찰성보리 ${\beta}-glucan$이 더 컸다. 보리전분에 ${\beta}-glucan$을 첨가하여 호화시켰을 때 상승작용으로 비스코그램의 점도를 증가시켰으며 그 효과는 메성전분에서 현저하였다.

The physicochemical characteristics of ${\beta}-glucan$ isolated from waxy and non-waxy barley were investigated. The hull-less waxy and non-waxy barley containing 6.5% and 5.3% of total ${\beta}-glucan$ respectively, were used as a starting material. The yield and ${\beta}-glucan$ content of crude ${\beta}-glucan$ from waxy barley was 5.54% and 62.9%, respectively, and those were higher than 3.34% and 59.2% from non-waxy barley. The crude ${\beta}-glucan$ purified with selective precipitation and enzymatic treatment to obtain the ${\beta}-glucan$ isolate of high purity (>99%). The total yield of purified ${\beta}-glucan$ from waxy and non-waxy barley was 4.46% and 2.59%, respectively. The surface appearance of the purified ${\beta}-glucan$ by scanning electron microscopy (SEM) showed randomly entangled multi-net structure of ${\beta}-glucan$ microfibrils. The melting temperature of ${\beta}-glucan$ from waxy and non-waxy barley measured by differential scanning calorimetry (DSC) was $184.6^{\circ}C$, and $180.3^{\circ}C$, respectively. DSC endotherm of ${\beta}-glucan$ solution showed 2 peaks near $68^{\circ}C$ and $84^{\circ}C$. Enthalpy of phase transition was higher in non-waxy ${\beta}-glucan$ than waxy ${\beta}-glucan$, and the intrinsic viscosity of ${\beta}-glucan$ solution from waxy barley was higher than that of non-waxy ${\beta}-glucan$. The pasting viscosity of barley starch with the purified ${\beta}-glucan$ determined by Rapid Visco-Analyzer was higher than that of barley starch without ${\beta}-glucan$, and the effect of ${\beta}-glucan$ on increasing the paste viscosity was greater in non-waxy barley starch.