Effect of Reaction Time on the Rheological Properties of Dextran Formed Solution Produced by Crude Dextransucrase from Leuconostoc rnesenteroides Sikhae

Leuconostoc mesenteroides Sikhae의 Crude Dextransucrase 반응시간에 따른 Dextran 생성액의 유변성

  • 박춘상 (고려대학교 식품공학과) ;
  • 이철호 (고려대학교 식품공학과)
  • Published : 1992.06.01

Abstract

Studies on the changes in rheological properties, molecular weight distribution and dextran yield after being reacted in lO%(w/w) sucrose concentration were performed with crude dextransucrase produced from Leuconostoc mesenteroides isolated from Sikhae. The reaction rate of dextran formation was monitored by sugar analysis with HPLC and by the changes in apparent viscosity. According to the periodate oxidation test, the dextran produced in this experiment was estimated to have 89% $\alpha$-(1->6) main linkages and 11% $\alpha$-(1->) side linkages. The rheological properties of the dextran solution formed changed with reaction time, and it was related to the changes in molecular weight distribution of dextran as determined by GPC analysis. As the reaction proceeded, the rheological behavior changed from Newtonian to non-Newtonian, showing Binghampseudoplastic and thixothropic flow behavior. The apparent viscosity of dextran formed solution increased with increasing reaction time, reached a maximum value of 2680 cP ($\gamma$=$33.75s^{-1}$, $25^{\circ}C$) by enzyme reaction for 8 hours, and then decreased. The temperature dependency of dextran formed solutions was well expressed by the Arrhenius equation and the activation energy reached a maximum value of 1.69 kcal/mole by enzyme reaction for 8 hours.

Keywords

Dextran formed solution rheological properties;molecular weight distribution;dextran yield;Leuconostoc mesenteroides Sikhae