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

Area of Science:

• Analytical Chemistry
• Food Science
• Spectroscopy

Background:

• Yellow turmeric (Curcuma longa) is commercially valuable for culinary, medicinal, and supplement use.
• Increased popularity leads to economic adulteration with botanical additives and chemical dyes.
• Ensuring turmeric purity is crucial for consumer safety and product integrity.

Purpose of the Study:

• To develop and validate a Fourier-transform infrared (FT-IR) spectroscopy method for identifying and quantifying adulterants in yellow turmeric powder.
• To detect the presence of white turmeric (Curcuma zedoaria) and Sudan Red G dye.
• To assess the accuracy and reliability of the developed spectroscopic method.

Main Methods:

• Preparation of mixed samples of yellow turmeric with varying concentrations of white turmeric (10-50%) and Sudan Red G dye (1-25%).
• Analysis of IR spectra using FT-IR spectroscopy to identify unique spectral fingerprints for adulterants.
• Development of partial least square regression (PLSR) models to quantify adulteration levels.

Main Results:

• Specific peaks at 748 cm⁻¹ for Sudan Red G and 1078 cm⁻¹ for white turmeric were identified as spectral fingerprints.
• The PLSR model for Sudan Red G achieved a coefficient of determination (R²v) of 0.97 and RMSEP of 1.3%.
• The PLSR model for white turmeric achieved an R²v of 0.95 and RMSEP of 3.0%.

Conclusions:

• FT-IR spectroscopy provides a reliable and accurate method for detecting and quantifying adulteration in yellow turmeric powder.
• The developed method can effectively identify both botanical (white turmeric) and chemical (Sudan Red G) adulterants.
• This technique offers a valuable tool for quality control in the turmeric industry to combat fraudulent practices.