Comparing vibrational spectroscopic method with wet chemistry to determine nutritional and chemical changes in solid state fermented oats grain (Avena sativa L.)

This study aimed to monitor nutritional and chemical changes of oats grain by wet chemistry and Fourier transformed infrared spectroscopy (FTIR). Oats grain fermented with or without inoculants of Aspergillus oryzae (AO), AO + Bacillus subtilis (C + D), Saccharomyces cerevisiae (SC), and Lactobacillus salivarius (LBS) was first analysed by wet chemistry for chemical and nutritional compositions. Then, analysed values were predicted by FTIR spectroscopy based on partial least square regression (PLSR). Crude protein increased with LBS and AO fermentations. AO and SC fermentation reduced dietary fibre, tannin and phytic acid contents. Highest fibre degradation was obtained from LBS fermentation, and highest organic acid production from AO and C + D fermentations. In the determination of chemical and nutrient contents, the method performance characteristics of FTIR-PLSR was better than that of wet chemistry methods, with precision values of 0.15-9.5% and accuracy values of around 100% (R-2 of 0.954-0.998 and standard error of prediction of 0.024-0.001). Furthermore, FTIR spectra deconvolution showed that oats starch had an overall 5-13% increased amorphous structure and 6-17% reduced proportion of crystalline structure due to the effect of fermentations. Fermentation lead to increased alpha-helix and side chain of peptides + amino acids, but decreased beta-sheet and beta-turn. Fermentation caused nutritionally and chemically valuable oats grain and FTIR-PLSR method produced a fast, non-destructive and robust determination.