## 4 Discussion  
FT-IR spectroscopic analysis allowed the detection of functional groups in different matrices, including plant-based foodstuffs. It also facilitated the determination of some phytochemical changes in the tested material. The broad bands at 3280 cm\({}^{-1}\) and 2930 cm\({}^{-1}\) can be attributed to the stretching vibrations of O-H, N-H, and C-H, respectively. In turn, the signal at \(\sim\)1725 cm\({}^{-1}\) is the result of C=O stretching and suggests the presence of fat [16; 17]. The spectra exhibited two strong signals at \(\sim\)1635 cm\({}^{-1}\) (Amide I) and \(\sim\)1540 cm\({}^{-1}\) (Amide II). The former is the result of the C=O stretching mode, while the peak at \(\sim\)1540 cm\({}^{-1}\) indicates the presence of the bending vibrations of N-H groups. These two signals can be attributed to the presence of protein in the samples. The bands between 1450 cm\({}^{-1}\) and 1300 cm\({}^{-1}\) can be assigned to the bending vibrations of CH\({}_{2}\), O-H, and C-O-H [17]. The signal at \(\sim\)1400 is noticeably stronger in the sample that was not subjected to lactic acid fermentation. It may be attributed to the presence of aromatic groups. This is in accordance with [18] who indicated that aromatic groups were inferred based on the band around 1407 cm\({}^{-1}\) (C-C stretch) and the peak near 798 cm\({}^{-1}\). Moreover, it was suggested that the changes in the region (absence of the peak in the area near 1400 cm\({}^{-1}\) in the fermented legume material) may be related to biochemical modifications (particularly in phenolic and aromatic groups) occurring through the fermentation process and microbial activity. Three signals at \(\sim\)760 cm\({}^{-1}\), \(\sim\)850 cm\({}^{-1}\), and 930 cm\({}^{-1}\) indicate the presence of \(\alpha\)-glycosidic links and may result from the presence of starch [19]. The FT-IR spectra of the tested lentil samples are similar to the results for water extracts of red lentils described by [20]. It has been suggested that some slight changes in spectra of fermented legume samples in the 750-1200 cm\({}^{-1}\) zone (a fingerprint region characteristic for carbohydrate components) and the amide I zone (presented also in this analysis) may be related to starch and protein [18]. Further, as indicated by [18], these changes contribute to various conversions of anti-nutritional components, e.g., tannins, which are of particular importance in the case of food production based on plant raw materials. Moreover, the visible band region 1657-1632 cm\({}^{-1}\) (characteristic for proteins and peptides) attributed to amide I (C=O stretching) [21; 22] was noted in all the tested legume samples. The changes may be an effect of protein and peptide hydrolysis occurring during the process of spontaneous fermentation with the participation of bacterial proteolytic enzymes. The differences within the protein-peptide fraction in the fermented samples (in comparison to the control variant) were also reflected in the images of the spectra obtained after the MALDI TOF/TOF analysis. Certain proteins present in legumes are described as strong allergens that may lead to adverse reactions in the human body. They may also lead to weaker absorption of other pulse-derived proteins in the gut [23; 24]. Hitherto, through the use of immunoblot analysis and mass spectrometry-based platforms, a subfamily of six lentil LTP isomers (designated as Lc-LTP1-6) has been identified and verified as immunologically potential allergens [2; 25; 26; 27]. One of them (the earliest identified lentil allergen) is \(\gamma\)-vicilin (50 kDa), considered the major allergen of lentils and designated Len c1 [28]. It is worth emphasizing that vicilin (also known as 7S globulin) belongs to the major storage proteins of legumes [29]. Another important protein is Len c2 with a molecular weight of about 66 kDa [30], while Len c3, belonging to the prolamin super-family, is a lipid transfer protein (LTPs) with a relatively small molecular weight (9 kDa).