## 3 Results and Discussion
### Volatile Compound Profile of the Different Wheat Wholemal Varieties  
Volatile compounds (VCs) that were \(>\)5% in at least one WW sample are shown in Figure 3, and the detailed VC profile is given in Supplementary File S5 Table S9. When comparing acetic acid in the WW samples, it was not established in all the nonfermented samples, as well as in both color WW samples fermented with the LUHS245 strain. The odor of acetic acid is described as sharp, pungent, sour, and vinegarly. However, in small concentrations, acetic acid is a flavor enhancer [15]. Heterofermentative LAB produces acetic acid, as well as specific esters, and reduces aldehydes to alcohols [79; 80]. In purple WW fermented with the LUHS122 strain, 1-butanol was found (8.03% of the total VC). The odor of 1-butanol is described as fused, oily, sweet, balsamic, and like whiskey. Acetoin, whose odor is described as creamy, dairy, sweet, oily, milky, buttery and like yogurt, was found only in nonfermented samples except purple WW. 1-Pentanol, which possesses a pungent, fermented, bready, yeasts, fused, winey, and solvent-like odor, was one of the main compounds of nonfermented 'Ada' WW (27.7% of the total VC). Also, 2,3-butanediol (fruity, creamy, buttery odor) was found in all nonfermented WW, and its concentration changed in relation to the LAB strain used for fermentation. When comparing nonfermented samples, hexanal was found only in 'Sarta' WW (29.9% of the total VC); also, after fermentation, this VC was established in LUHS29 fermented 'Ada', 'Sarta', and purple WW (2.67, 6.66, and 5.51% of the total VC, respectively), in LUHS245 strain fermented 'Ada' and 'Sarta', and in LUHS122 strain fermented 'Sarta' WW. The hexanal concentration was 28.8% of the total VC. The odor of hexanal is described as aldehyde, fatty, green, and powerful. It was reported that the VC in the sourdoughs varied in relation with the starter culture used [81]. According to [PERSON] (1998) and [PERSON] et al. (2016), the main VCs in wheat sourdough are acetic acid, hexanal, and octanel [48; 82]. The lipid oxidation is the main factor for hexanal formation [18]. A high concentration of hexanal is undesirable, and the heterofermentative LAB could reduce its negative flavor by converting aldehydes to alcohols [18; 83; 84]. It was reported that hexanol is present in all fermentations [15]. Ethyl butyrate (sweet, fruity, tutti frutti, lifting, and diffusive odor) was found only in LUHS122 fermented purple WW (19.9% of the total VC). Ethyl lactate (sweet, fruity, acidic, etherial with a brown nuance odor) was found only in LUHS29 fermented 'Ada', 'Sarta', and blue WW (3.61, 5.05, and 5.99% of the total VC, respectively). Butanoic acid (sharp, dairy-like, cheesy, buttery with a fruity nuance odor) was one of the main VCs in LUHS122 fermented purple WW (37.7% of the total VC), while 1-Hexanol (citrus, fresh, floral, oily, sweet odor) was established in most of the samples except in purple WW fermented with the LUHS122 strain. L-lactic acid (sugar, wheat, malt, sweet odor) was found in 'Ada' and purple WW fermented with the LUHS29 strain and in 'Ada', 'Sarta', and blue WW fermented with the LUHS245 strain. More than half of the entire VC profile in blue WW fermented with the LUHS122 strain was 4-methylpentanoic acid (54.8% of the total VC), whose odor is described as pungent cheese. Furthermore, 2-Heptenal (intense green, fatty, oily, with fruity overtones odor) was found in most of the WW samples except in nonfermented 'Sarta', purple WW, and blue WW fermented with the LUHS122 strain. Hexanoic acid, whose odor is described as sour, fatty, sweat, and like cheese, was not formed in nonfermented 'Ada' and both colored WW samples, while 2-PentyIfuran (fruity, green, earthy beany vegetable like nuances odor) was not established in only two WW samples (blue WW fermented with the LUHS122 strain and nontreated purple WW).