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Fourier Transform Infrared Spectroscopy for Kona Coffee Authentication

Authors

  • Jun Wang,

    1. Authors Wang, Gautz, and Li are with Molecular Biosciences and Bioengineering, author Jun is with Human Nutrition Food and Animal Science, author Bittenbender is with Tropical Plant and Soil Sciences, Univ. of Hawaii, Honolulu, HI, U.S.A. Direct inquiries to author Jun (E-mail: soojin@hawaii.edu).
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  • Soojin Jun,

    1. Authors Wang, Gautz, and Li are with Molecular Biosciences and Bioengineering, author Jun is with Human Nutrition Food and Animal Science, author Bittenbender is with Tropical Plant and Soil Sciences, Univ. of Hawaii, Honolulu, HI, U.S.A. Direct inquiries to author Jun (E-mail: soojin@hawaii.edu).
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  • H.C. Bittenbender,

    1. Authors Wang, Gautz, and Li are with Molecular Biosciences and Bioengineering, author Jun is with Human Nutrition Food and Animal Science, author Bittenbender is with Tropical Plant and Soil Sciences, Univ. of Hawaii, Honolulu, HI, U.S.A. Direct inquiries to author Jun (E-mail: soojin@hawaii.edu).
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  • Loren Gautz,

    1. Authors Wang, Gautz, and Li are with Molecular Biosciences and Bioengineering, author Jun is with Human Nutrition Food and Animal Science, author Bittenbender is with Tropical Plant and Soil Sciences, Univ. of Hawaii, Honolulu, HI, U.S.A. Direct inquiries to author Jun (E-mail: soojin@hawaii.edu).
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  • Qing X. Li

    1. Authors Wang, Gautz, and Li are with Molecular Biosciences and Bioengineering, author Jun is with Human Nutrition Food and Animal Science, author Bittenbender is with Tropical Plant and Soil Sciences, Univ. of Hawaii, Honolulu, HI, U.S.A. Direct inquiries to author Jun (E-mail: soojin@hawaii.edu).
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Abstract

ABSTRACT:  Kona coffee, the variety of “Kona typica” grown in the north and south districts of Kona-Island, carries a unique stamp of the region of Big Island of Hawaii, U.S.A. The excellent quality of Kona coffee makes it among the best coffee products in the world. Fourier transform infrared (FTIR) spectroscopy integrated with an attenuated total reflectance (ATR) accessory and multivariate analysis was used for qualitative and quantitative analysis of ground and brewed Kona coffee and blends made with Kona coffee. The calibration set of Kona coffee consisted of 10 different blends of Kona-grown original coffee mixture from 14 different farms in Hawaii and a non-Kona-grown original coffee mixture from 3 different sampling sites in Hawaii. Derivative transformations (1st and 2nd), mathematical enhancements such as mean centering and variance scaling, multivariate regressions by partial least square (PLS), and principal components regression (PCR) were implemented to develop and enhance the calibration model. The calibration model was successfully validated using 9 synthetic blend sets of 100% Kona coffee mixture and its adulterant, 100% non-Kona coffee mixture. There were distinct peak variations of ground and brewed coffee blends in the spectral “fingerprint” region between 800 and 1900 cm−1. The PLS-2nd derivative calibration model based on brewed Kona coffee with mean centering data processing showed the highest degree of accuracy with the lowest standard error of calibration value of 0.81 and the highest R2 value of 0.999. The model was further validated by quantitative analysis of commercial Kona coffee blends. Results demonstrate that FTIR can be a rapid alternative to authenticate Kona coffee, which only needs very quick and simple sample preparations.

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