A Fast and Robust FTIR-ATR Coupled Chemometric Determination of Chemical and Molecular Structure of Wheat (Triticum aestivum L.) under a Series of Microbial Fermentation Processes

This study aimed to ferment wheat grain by optimised bacteria, yeast and fungal fermentations. Crude protein, tannin, phytic acid and lactic acid contents of samples taken at 24 h intervals determined by chemical methods were compared with those of infrared (IR) spectro-chemometry. Secondary protein components were further quantified with IR spectra deconvolution method. The results indicated that some fermentations increased crude protein of wheat, whilst its tannin and phytic acid degraded in all fermentations. Wheat enriched with lactic acid content in all fermentations. FT-IR spectroscopic method accurately (99.99% of recovery) and precisely (regression coefficient of prediction R2 = 0.999, P <0.0001) predicted these nutrient contents. Fermentation positively caused a re-organised secondary protein conformation; the percentages of β-sheet and α-helix increased by 68 and 140%, respectively, whereas the random coil decreased by 63%. FT-IR spectrometry combined with suitable chemometric tools provided a fast and robust monitoring of chemical and structural changes during microbial fermentation.