Use of NIR spectroscopy and 3D principal component analysis for particle size control of dried medicinal plants

Abstract

The regular or in-line measurement of particle size is an essential requirement for quality control throughout food industry to ensure a consistent product output. Non-invasive spectroscopy in the near infrared range from 904 - 1699 nm (NIR) was applied to investigate the possibility of differentiation of five different medicinal plants (chamomile, dandelion, nettle, broadleaf plantain and yarrow). Dry plants were milled and after sieving four fractions were obtained with following particle sizes: 450 μm. Raw spectra and first derivative of raw spectra were recorded and principle component analysis (PCA) of first three factors was applied (3D PCA). 3D PCA showed better differentiation for first derivative compared to the raw spectra for all five medicinal plants and all analyzed particle sizes. Particle size fractions were photographed using microscope in order to explain analysis results for fractions 280-450 μm and >450 μm, where the presence of smaller particles was visible for all five medicinal plants.

Keywords

• near infrared spectroscopy
• principle component analysis
• particle size
• medicinal plants