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Detection of Additives and Chemical Contaminants in Turmeric Powder Using FT-IR Spectroscopy

United States Department of Agriculture/Agricultural Research Service, Environmental Microbial and Food Safety Laboratory, Bldg. 303, Beltsville Agricultural Research Center, 10300 Baltimore Ave., Beltsville, MD 20705-2350, USA
China Agricultural University, National R&D Centre for Agro-Processing Equipments, Beijing 100083, China
Author to whom correspondence should be addressed.
Foods 2019, 8(5), 143;
Received: 28 March 2019 / Revised: 22 April 2019 / Accepted: 23 April 2019 / Published: 26 April 2019
(This article belongs to the Special Issue Rapid Detection Methods for Food Fraud and Food Contaminants)
PDF [6699 KB, uploaded 26 April 2019]
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Yellow turmeric (Curcuma longa) is widely used for culinary and medicinal purposes, and as a dietary supplement. Due to the commercial popularity of C. longa, economic adulteration and contamination with botanical additives and chemical substances has increased. This study used FT-IR spectroscopy for identifying and estimating white turmeric (Curcuma zedoaria), and Sudan Red G dye mixed with yellow turmeric powder. Fifty replicates of yellow turmeric—Sudan Red mixed samples (1%, 5%, 10%, 15%, 20%, 25% Sudan Red, w/w) and fifty replicates of yellow turmeric—white turmeric mixed samples (10%, 20%, 30%, 40%, 50% white turmeric, w/w) were prepared. The IR spectra of the pure compounds and mixtures were analyzed. The 748 cm−1 Sudan Red peak and the 1078 cm−1 white turmeric peak were used as spectral fingerprints. A partial least square regression (PLSR) model was developed for each mixture type to estimate adulteration concentrations. The coefficient of determination (R2v) for the Sudan Red mixture model was 0.97 with a root mean square error of prediction (RMSEP) equal to 1.3%. R2v and RMSEP for the white turmeric model were 0.95 and 3.0%, respectively. Our results indicate that the method developed in this study can be used to identify and quantify yellow turmeric powder adulteration. View Full-Text
Keywords: FT-IR; Sudan dye; white turmeric; turmeric; curcumin; adulteration; food safety FT-IR; Sudan dye; white turmeric; turmeric; curcumin; adulteration; food safety

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Dhakal, S.; Schmidt, W.F.; Kim, M.; Tang, X.; Peng, Y.; Chao, K. Detection of Additives and Chemical Contaminants in Turmeric Powder Using FT-IR Spectroscopy. Foods 2019, 8, 143.

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