## 3 Results and Discussion
### Acidity and Microbiological and Chromaticity Characteristics of Lentil Wholemeal Samples
In all cases, the same tendencies were found: with an increasing duration of fermentation, the L* and b* values of the lentils decreased and the a* values increased. Lentil L*, a*, and b* values showed statistically significant correlations with pH and LAB viable counts (with pH: r = 0.763, \(p<0.001\); r = \(-0.679\), \(p<0.001\); and r = 0.839, \(p<0.001\), respectively; with LAB viable counts: r = \(-0.710\), \(p<0.001\); r = 0.552, \(p<0.001\); and r = \(-0.799\), \(p<0.001\), respectively). Analysed factors (fermentation conditions, lentil growing conditions, and fermentation duration) and their interactions were statistically significant (\(p<0.001\)) for the colour coordinate values of lentil samples, except for the interaction between growing conditions, type of fermentation, and fermentation durations on a* values (see supplementary file: Table S1). The colour of the lentil is a key quality parameter due to its impact on the acceptability of the legume products. The lentil colour ranges from light tan to dark brown, and the latter is often referred as being a lower quality product. Furthermore, a lighter colour can be linked to a loss of nutrients or other secondary metabolites, such as polyphenic compounds [2]. Our study discovered that the changes in lentil colour can be found during the fermentation process. It was reported that the anthocyanins can be hydrolysed by bacterial \(\beta\)-glucosidase enzymes and converted to small phenolic compounds [43]. Likewise, other flavonoid pigments (flavonols, flavones isoflav, etc.) may be degraded by bacterial enzymes [43]. Excreted bacterial enzymes break glycosidic bonds to form aglycones and, then, the latter, after prolonged fermentation, may be further be converted into smaller phenolic compounds [43; 44]. Moreover, yellow to orange pigments--carotenoids [45]--can degrade under LAB fermentation conditions, producing volatile low-molecular weight carotenoid derivatives, such as \(\beta\)-ionone and \(\beta\)-damascenone [46]. Finally, further studies are needed to explain, in detail, the colour changes in lentils during fermentation but we found correlations between the lentil colour characteristics and the main fermentation parameters (pH and LAB viable counts)--exposing that the changes occurring during lentil fermentation are very complex and should be taken into consideration during its processing. Free Amino Acid Profile and \(\gamma\)-Aminobutyric Acid (GABA) Concentration in lentil Wholemeal Samples  
The non-essential free amino acid concentrations in lentil samples are presented in Table 2, and GABA concentrations in lentil samples are presented in Figure 2. The fermentation process proved to be a significant factor of reduction in arginine, asparagine, glutamine, and aspartic acid concentrations in most of the cases, while glutamic acid, glycine, alanine, and proline concentrations in fermented lentil samples were significantly higher in most cases, in comparison to respective control samples. Moreover, serine concentration in SMF samples (SMFLR24, SMFLR48, SMFLR24, and SMFLR48) was significantly lower, while its concentration in SSF samples (SSFLR24, SSFLR48, SSFLR24, and SSFLR48) was significantly higher than the respective control sample groups. Additionally, SMFLR24, SMFLR48, SSFLR24, and SSFLR48 samples contained significantly lower concentration of GABA, while its concentration was significantly higher in most of SMF and SSF LR samples, in comparison with the respective control samples. L control samples (C\({}_{\rm L}\)SM and C\({}_{\rm L}\)SS) contained significantly higher concentrations of arginine, asparagine, and alanine than the LR control samples. Meanwhile, LR control samples (C\({}_{\rm L}\)SR and C\({}_{\rm L}\)RS) contained significantly higher concentrations of glutamic acid, in comparison with L control samples. Argin concentration in almost all fermented samples was reduced to undetectable levels.