Concepts and application of near infrared spectroscopy for rapid and nondestructive analysis of essential oils: a review

The authenticity and the chemical composition of essential oils (EOs) have become the crucial issues in the trade of these oils. However, gas chromatography-mass spectrometry (GC-MS), regarded as the gold standard to analyse the authenticity and chemical composition, is often considered time-consuming, destructive, and expensive. Near-Infrared (NIR) spectroscopy technology presents itself as an as alternative tool for analysing the quality of EOs which is non-destructive, cost-effective, rapid and suitable for the in-line measurement. When combined with chemometrics, this technology has the potential to predict EOs yield from plant parts, estimate level of major constituents, determine authenticity, and differentiate chemotypes of EOs. This article briefly summarizes the basic concepts of NIR spectroscopy technology and chemometrics. It then presents the potential of NIR spectroscopy as alternative analytical tool to ensure EOs quality by highlighting numerous studies conducted over the last 24 years. Future possibilities for development of NIR spectroscopy technology in EOs assessment are also discussed.