Analysis of Thymoquinone Content in Black Cumin Seeds Using Near-Infrared Reflectance Spectroscopy

Area of Science:

• Agricultural Science
• Analytical Chemistry
• Spectroscopy

Background:

• Thymoquinone (TMQ) is the primary bioactive compound in Nigella sativa seeds, known for its therapeutic properties.
• Traditional quantification methods like HPLC are accurate but not feasible for high-throughput screening.

Purpose of the Study:

• To assess Near-Infrared Reflectance Spectroscopy (NIRS) as a rapid, non-destructive alternative for TMQ quantification in black cumin seeds.
• To develop and validate NIRS calibration models for predicting TMQ content.

Main Methods:

• Analysis of 780 black cumin seed samples across multiple years.
• Development of calibration models using modified partial least squares regression.
• Independent validation and continuous updating of calibration equations with new data.

Main Results:

• NIRS achieved high predictive performance (r² = 0.85; SEP = 1.18 mg g⁻¹) for TMQ content.
• Continuous updating of calibration models improved prediction accuracy.
• NIRS effectively identified genotypes with high TMQ content, particularly with updated models.
• Key spectral wavelengths (around 2106 nm and 2254 nm) were identified as crucial for TMQ prediction.

Conclusions:

• NIRS is a viable and efficient tool for rapid phenotyping of TMQ in black cumin seeds.
• The study highlights the importance of updating calibration models for sustained accuracy.
• NIRS facilitates large-scale screening and selection of high-value black cumin genotypes.