Extraction of physical properties from Vis/NIR spectroscopic measurements.

The size distribution of suspended particles is an important property for many particulated media in food and polymer industry. Nowadays, particle size analysis is mostly done with techniques that rely on laser light scattering, dynamic light scattering or electron microscopy. However, extensive sample preparation is often needed before such measurements can be performed. Therefore, these measurement techniques are not suitable for online analysis of the particle size distribution. Vis/NIR spectroscopy is already widely used to monitor production processes online in industry. As the measured spectra give insight into the absorption, it is mainly used to determine composition-related quality parameters. Nevertheless, measured Vis/NIR spectra are, next to absorption, also the result of light scattering. Since the light scattering originates from the samples physical microstructure, these physical properties can be extracted from the measured Vis/NIR spectra. In this study, an estimation algorithm will be developed to estimate the particle size distribution from Vis/NIR spatially resolved reflectance spectra of oil-in-water emulsions. This algorithm will rely on an inversion of the Mie solution for Maxwells equations in combination with a regularization and estimation procedure. The Mie solution gives the forward relation between the properties of the spherical particles (size, material properties, ) in a suspension and the scattering properties of these particles at a certain wavelength.

Keywords:Milk, Vis/NIR Spectroscopy, Suspensions, Emulsions, Light Scattering, Physical Properties, Particle Size Distribution

Disciplines:Biomaterials engineering, Biological system engineering, Biomechanical engineering, Other (bio)medical engineering, Environmental engineering and biotechnology, Industrial biotechnology, Other biotechnology, bio-engineering and biosystem engineering