Multivariate FTIR analysis of substrates for protein, polysaccharide, lipid and microbe content: potential for...

Components of fermentation processes such as protein, polysaccharide and lipid, as well as microbes, such as fungi grown on solid substrates, are difficult to measure in situ. The potential of Fourier Transform Infrared (FTIR) analysis of solid-state fermentations from mid-infrared absorption spectra has been investigated. The problem under consideration was to build a calibration model containing no irrelevant information to enable a multivariate mathematical approach for prediction of component concentrations. Methods for solid sample preparation and preprocessing of FTIR data were developed to assure Beer-Lambert law compliance and produce a well-conditioned multivariate system. The model was tested using composite samples of zein protein, corn starch and azolectin lipid, and corn samples containing known levels of fungal contamination. Preliminary concentration estimates were remarkably close to the correct values, with less than 5% standard error of prediction for all components measured.