Quality of foods strongly depends on their microstructure and composition. Examples include sponginess of bread, crispness or crunchiness of crackers, firmness or sweetness of fruits. Processing of foods also affects their microstructure and composition: existing structures are destroyed and new ones are formed; some constituents are changed and new ones are created. Therefore, rapid and accurate measurement of food microstructure and composition and how they change during processing operations is essential for the production of high quality foods.

Microstructure and composition (and their changes) strongly determine light propagation behavior (e.g. diffuse reflectance) in the illuminated food samples, mostly attributed by scattering and absorption phenomena. However,  multiple light scattering increases photon pathlengths inside the biological structure resulting in increased absorbance for the same concentration level, such that the measured reflectance or transmittance spectra result from the interplay of both scattering and absorption. Since the traditional NIR spectroscopy technique only measures the diffuse reflectance (or transmission), which is a combination of scattering and absorption effects, further improvements could be implemented for resolving this problem.

This research was performed in the context of the EU project InsideFood (FP7-226783). In this study, the potential of spatially resolved spectroscopy for non-invasively characterizing microstructure and composition of the microstructured foods (model foods) by means of their optical properties (absorption and reduced scattering coefficients) has therefore been investigated.