Trait-led valorization of Northeastern Sub-Himalayan Indian turmeric landraces: Curcuminoids, essential oil, minerals, colour metrics, and antioxidant capacity for nutraceutical and industrial uses

Abstract

Forty-two indigenous turmeric (Curcuma longa L.) landraces from Northeast India’s sub-Himalayan region were profiled to establish trait-led opportunities for valorization. Curcuminoids were quantified by high-performance liquid chromatography, essential oils by gas chromatography-mass spectrometry, minerals by atomic absorption spectrophotometry, and antioxidant activity by Ferric Reducing Antioxidant Power Assay. Significant (p < 0.05) variation was found across all traits. Total curcuminoids ranged from 0.42 to 5.69 %, with curcumin as the major fraction, followed by bisdemethoxycurcumin and demethoxycurcumin. Essential oil yields (1.45–8.92 %) were dominated by tumerone (29.16–58.20 %), curlone (6.43–25.86 %), β-sesquiphellandrene (2.41–17.5 %), and zingiberene (3.07–30.0 %), though some genotypes exhibited unique profiles. Microminerals varied widely, notably Fe (77.7–332 ppm), Zn (29–203 ppm), Mn (60–317 ppm) and Cu (1.25–5.70 ppm). Antioxidant capacity correlated strongly with phenolic content and total curcuminoids (r = 0.74–0.97). Multivariate analyses (Principal Component Analysis, Hierarchical Cluster Analysis) revealed distinct chemotypic clusters, with Meghalaya and Nagaland genotypes enriched in curcuminoids and micro-minerals, while Manipur and Assam excelled in macro-elements (K, Ca, Mg). A positive correlation between a* colour value and curcuminoids supports its use as a rapid, non-destructive quality screening tool, while a negative correlation among key oil constituents suggests inherent chemotypic trade-offs. This first integrated chemoprofiling of Northeast Indian turmeric highlights elite genotypes with superior phytochemical and functional traits, providing direct leads for nutraceutical product development, essential oil exploitation, and trait-based breeding and conservation strategies.