Korean Journal of Food Science and Technology (한국식품과학회지)

Korean Society of Food Science and Technology (한국식품과학회)
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Changes in Microflora, Enzyme Activities and Microscopic Structure of Waxy Rice and Steeping Water in Response to Different Steeping Conditions During Preparation of Gangjung

강정 제조시 찹쌀의 수침조건에 따른 찹쌀과 수침액의 미생물상, 효소활성 및 미세구조 변화

  • Kim, Haeng-Ran (National Academy of Agricultural Science, RDA) ;
  • Kim, Kyung-Mi (National Academy of Agricultural Science, RDA) ;
  • Kim, Kwang-Ok (Department of Food Science and Technology, Ewha Womans University)
  • 김행란 (농촌진흥청 국립농업과학원) ;
  • 김경미 (농촌진흥청 국립농업과학원) ;
  • 김광옥 (이화여자대학교 식품공학과)
  • Published : 2009.12.31
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Abstract

This study was conducted to investigate the effects of steeping periods and temperatures of waxy rice on the microflora and enzyme activities of steeping water and waxy rice, as well as on the microscopic structures of waxy rice during the preparation of gangjung. When the steeping water was 15 and $35^{\circ}C$, yeast and lactic acid bacteria were the major microflora after 1 day. After 11 days, Lactobacillus spp. were the major bacteria, while Bacillus spp. were the primary microflora after 21 days. At $25^{\circ}C$ the primary species were Bacillus spp., Leuconostoc spp., and Bacillus spp. after 1, 11 and 21 days, respectively. The $\alpha$-amylase activity of steeping water increased proportionally with the increase of temperature and period, while the protease activity tended to increase for 11 days, but decreased at 21 days. The enzyme activities of the steeped waxy rice, especially the $\alpha$-amylase activity, decreased with higher steeping temperature, while the $\beta$-amylase and glucoamylase activity remained constant for up to 21 days. Observation using scanning electron microscopy indicated that intracellular cleavage of steeped waxy rice endosperm resulted in a rough surface morphology due to the exposure of polygonal starch granules. Tiny pinholes on the surface of waxy rice starch granules were also observed after steeping for 11 days.

수침조건에 따라 수침찹쌀과 수침액의 미생물학적 변화와 효소활성 및 구조적 특성을 살펴본 결과 수침액의 미생물상에서, 수침초기에는 젖산균이 우세하였고, 수침기간이 길어짐에 따라 미생물 균수가 급속히 증가하면서 젖산균과 Bacillus spp.이 우세 균총으로 관찰되다가 수침이 계속되면서 모든 미생물이 감소하는 경향을 보였으며 그 중에서 Bacillus spp.이 가장 많이 관찰되었다. 수침액의 $\alpha$-amylase는 수침온도와 수침기간이 증가함에 따라 지속적으로 활성이 증가하였고, protease 활성은 수침기간이 길어짐에 따라 활성이 증가한 후 감소하는 경향을 보였다. 수침 찹쌀의 $\alpha$-amylase는 수침온도가 높을수록 감소하였고, $\beta$-amylase와 glucoamylase는 수침 1일에 증가하여 수침 21일까지 일정하였다. 수침찹쌀의 미세구조를 살펴보면, 세포벽이 떨어져 나간 흔적이 보이고 다각형의 찹쌀전분입자들이 노출되면서 표면이 거칠어 보였다. 또한 찹쌀전분 입자 표면의 미세한 구멍이 수침 11일 이후 관찰되어 효소작용의 결과와 일치하는 경향을 나타냈다.

Keywords

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