Integrated Analytical Profiling Reveals Quality Variability and Adulteration in Marketed Turmeric Powders

Abstract

Turmeric (Curcuma longa L.) is a widely used medicinal spice whose marketed powder may show quality variation and be susceptible to adulteration. This study comparatively evaluated one locally procured turmeric powder sample (L1) and three branded samples (B1–B3) through organoleptic assessment, phytochemical screening, thin-layer chromatography (TLC), extractive and ash values, moisture content, preformulation parameters, qualitative adulteration tests and UV spectrophotometric assessment of curcumin. Tannins, phenols, flavonoids and terpenoids were detected in all samples, with minor variations in alkaloids and saponins. TLC showed curcuminoid-related spots in all samples, with Rf values ranging from 0.66 to 0.87. L1 had the highest water-soluble and alcohol-soluble extractive values and the highest UV absorbance. Among the branded samples, B2 showed the best flowability, whereas B3 showed very poor flowability based on Carr’s index and Hausner’s ratio. All samples were negative in the qualitative tests for chalk powder, lead chromate, Sudan dye, sand and starch, but all were positive in the qualitative colour-based screening test for Metanil yellow. UV absorption maxima ranged from 429.3 to 433.7 nm, while relative absorbance-based purity values for B1, B2 and B3 were 95.52%, 93.31% and 93.16%, respectively, relative to L1. These preliminary findings indicate sample-level quality variability and support the need for replicate analysis and confirmatory instrumental testing before definitive conclusions regarding adulteration or quantitative purity are drawn.