Quantitative analysis by mid-infrared spectrometry in food and agro-industrial fields

Abstract

Thanks to what has been achieved by the Fourier transform, infrared spectroscopy can now become a state of the art device in the quality control laboratories if we consider its precision and the gain in time it ensures compared to traditional analysis methods such as HPLC chromatography. Moreover, the increasing number of new mathematical regression methods such as Partial Least Square ( PLS) regression allows the multicomponent quantitative analysis in mixtures. Nevertheless, the efficiency of infrared spectrometry as a quantitative analysis method often depends on the choice of an adequate presentation for the sample. In this document, we shall demonstrate several techniques such as diffuse reflectance and Attenuated Total Reflectance (ATR) which can be according to the various physical states of the mixtures. The quantitative analysis of real samples from the food industry enables us to estimate its precision. For instance, the analysis of the three main components (glucose, fructose and maltose) in the glucose syrups can be done (using ATR) with a precision in the region of 3% whereas the time required to obtain an analysis report is about 5 minutes. Finally multicomponent quantitative analysis is quite feasable by mid-IR spectroscopy.