Rapid classification of basil chemotypes by various vibrational spectroscopy methods

Area of Science:

• Analytical Chemistry
• Spectroscopy
• Chemometrics
• Plant Science

Background:

• Basil (Ocimum basilicum) exhibits diverse chemotypes with varying volatile compound profiles.
• Accurate identification and quantification of valuable and potentially carcinogenic compounds in basil are crucial for industry and consumer safety.
• Traditional methods for analyzing basil composition can be time-consuming and labor-intensive.

Purpose of the Study:

• To evaluate the potential of vibrational spectroscopy techniques for analyzing basil chemotypes.
• To identify and quantify volatile components, including carcinogenic substances, in different basil varieties.
• To assess the applicability of these spectroscopic methods for quality control in basil oil production.

Main Methods:

• Utilized vibrational spectroscopy methods: Attenuated Total Reflectance/Fourier-transform infrared (ATR/FT-IR), FT-Raman, and Near-Infrared (NIR) spectroscopy.
• Analyzed volatile components in isolated essential oils, solvent extracts, and air-dried basil herbs.
• Employed chemometric methods for NIR data interpretation and spectral analysis for IR and Raman data.

Main Results:

• All tested vibrational spectroscopy methods reliably determined main volatile components in various basil matrices.
• IR and Raman spectra allowed direct discrimination of basil chemotypes by identifying characteristic key bands of volatiles.
• NIR calibrations accurately predicted methyleugenol (R² = 0.951) and estragole (R² = 0.890) content in air-dried basil leaves.

Conclusions:

• Vibrational spectroscopy offers efficient and reliable tools for the identification and quantification of compounds in basil.
• These methods facilitate the selection of specific basil plants meeting regulatory and consumer demands.
• Spectroscopic techniques are valuable for industrial quality control of basil oil, including purification and blending processes.