Korean Journal of Plant Resources (한국자원식물학회지)

The Plant Resources Society of Korea (한국자원식물학회)
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Rapid Measure of Color and Catechins Contents in Processed Teas Using NIRS

근적외선 분광광도계를 이용한 차 제품의 색상 및 카테킨류의 신속 측정

  • Chun, Jong-Un (Dept. of Well-being Resources, Sunchon National University)
  • 천종은 (순천대학교 웰빙자원학과)
  • Received : 2010.02.02
  • Accepted : 2010.08.13
  • Published : 2010.08.31
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Abstract

This study was done to measure the color and catechins contents in processed teas using the whole bands (400~2500 nm) with near-infrared spectroscopy(NIRS). The powder colors of 109 processed teas were measured with a colorimeter. The a/b ratios in Hunter color scale in processed teas accounted for about 98.9% of the variation in the fermentation degree(FD), indicating that the a/b ratio was a very useful trait for assessing fermentation degree. Also tea powders were scanned in the visible bands used with NIRSystem. The calibration equations for powder colors were developed using the regression method of modified partial least squares(MPLS) with the internal cross validation. The equations had low SECV (standard errors of cross-validation), and high $R^2$ (coefficient of determination in calibration) values with 0.996~1.00, indicating that the visible bands(400~700 nm) with NIRS could be used to rapidly measure the variables related to powder color and fermentation degree. Also another powders of 137 processed teas were scanned at 780~2500 nm bands in the reflectance mode. The calibration equations were developed using the regression method of MPLS with the internal cross validation. The equations had low SECV, and high $R^2$ (0.896~0.983) values, showing that NIRS could be used to rapidly discriminate the contents of EGC($R^2$=0.919), EC(0.896), EGCg(0.978), ECg(0.905) and total catechins(0.983) in processed teas with high precision and ease.

녹차, 부분발효차, 발효차 및 후발효차 등 다양한 차 제품 분말을 NIRSystem를 이용하여 전 대역(400-2500 nm)에서 스펙트럼을 얻어 중회귀분석에 의해 색상 관련 특성 및 카테킨류 성분에 대한 검량식을 유도하였다. Hunter color scale에서 발효정도의 변이를 a/b로 98.7% 설명될 수 있어 a/b값으로 차제품의 발효정도를 추정할 수 있다. MPLS를 이용하여 작성된 검량식의 결과 L값의 검량식 작성시 결정계수는 0.997, a값의 결정계수는 1.00, b값의 결정계수는 0.996, a/b값의 결정계수는 0.999로 매우 높았다. MPLS를 이용하여 작성된 검량식의 결과 EGC, EC, EGCg, ECg 및 총 카테킨의 결정계수는 각각 0.919, 0.896, 0.978, 0.905 및 0.983으로 매우 높았다. 차 제품 분말의 색상관련 특성들(L, a, b, a/b) 및 카테친류 (EGCg, EGC, EC, ECg 및 총 카테킨) 의 검량식 정확도가 매우 높아서 NIRS의 가시광선 대역(400~700 nm)및 근적외선 대역(780~2500 nm)에서 동시에 두 특성의 성분을 1~2분 내로 측정이 가능하다.

Keywords

References

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