Evaluation of Turmeric Powder Adulterated with Metanil Yellow Using FT-Raman and FT-IR Spectroscopy

Dhakal, Sagar; Chao, Kuanglin; Schmidt, Walter; Qin, Jianwei; Kim, Moon; Chan, Diane

doi:10.3390/foods5020036

Open AccessArticle

Evaluation of Turmeric Powder Adulterated with Metanil Yellow Using FT-Raman and FT-IR Spectroscopy

by

Sagar Dhakal

,

Kuanglin Chao

^*,

Walter Schmidt

,

Jianwei Qin

,

Moon Kim

and

Diane Chan

United States Department of Agriculture/Agricultural Research Service, Environmental Microbial and Food Safety Laboratory, Bldg. 303, Beltsville Agricultural Research Center East, 10300 Baltimore Ave., Beltsville, MD 20705-2350, USA

^*

Author to whom correspondence should be addressed.

Foods 2016, 5(2), 36; https://doi.org/10.3390/foods5020036

Submission received: 14 April 2016 / Revised: 6 May 2016 / Accepted: 11 May 2016 / Published: 17 May 2016

(This article belongs to the Special Issue Microbial, Chemical and Physical Contamination of Food Products)

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Abstract

Turmeric powder (Curcuma longa L.) is valued both for its medicinal properties and for its popular culinary use, such as being a component in curry powder. Due to its high demand in international trade, turmeric powder has been subject to economically driven, hazardous chemical adulteration. This study utilized Fourier Transform-Raman (FT-Raman) and Fourier Transform-Infra Red (FT-IR) spectroscopy as separate but complementary methods for detecting metanil yellow adulteration of turmeric powder. Sample mixtures of turmeric powder and metanil yellow were prepared at concentrations of 30%, 25%, 20%, 15%, 10%, 5%, 1%, and 0.01% (w/w). FT-Raman and FT-IR spectra were acquired for these mixture samples as well as for pure samples of turmeric powder and metanil yellow. Spectral analysis showed that the FT-IR method in this study could detect the metanil yellow at the 5% concentration, while the FT-Raman method appeared to be more sensitive and could detect the metanil yellow at the 1% concentration. Relationships between metanil yellow spectral peak intensities and metanil yellow concentration were established using representative peaks at FT-Raman 1406 cm⁻¹ and FT-IR 1140 cm⁻¹ with correlation coefficients of 0.93 and 0.95, respectively.

Keywords: FT-Raman; FT-IR; turmeric powder; metanil yellow; quantitative analysis

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MDPI and ACS Style

Dhakal, S.; Chao, K.; Schmidt, W.; Qin, J.; Kim, M.; Chan, D. Evaluation of Turmeric Powder Adulterated with Metanil Yellow Using FT-Raman and FT-IR Spectroscopy. Foods 2016, 5, 36. https://doi.org/10.3390/foods5020036

AMA Style

Dhakal S, Chao K, Schmidt W, Qin J, Kim M, Chan D. Evaluation of Turmeric Powder Adulterated with Metanil Yellow Using FT-Raman and FT-IR Spectroscopy. Foods. 2016; 5(2):36. https://doi.org/10.3390/foods5020036

Chicago/Turabian Style

Dhakal, Sagar, Kuanglin Chao, Walter Schmidt, Jianwei Qin, Moon Kim, and Diane Chan. 2016. "Evaluation of Turmeric Powder Adulterated with Metanil Yellow Using FT-Raman and FT-IR Spectroscopy" Foods 5, no. 2: 36. https://doi.org/10.3390/foods5020036

APA Style

Dhakal, S., Chao, K., Schmidt, W., Qin, J., Kim, M., & Chan, D. (2016). Evaluation of Turmeric Powder Adulterated with Metanil Yellow Using FT-Raman and FT-IR Spectroscopy. Foods, 5(2), 36. https://doi.org/10.3390/foods5020036

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

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Evaluation of Turmeric Powder Adulterated with Metanil Yellow Using FT-Raman and FT-IR Spectroscopy

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