# Bread Biopreservation through the Addition of Lactic Acid Bacteria in Sourdough
## 3 Results and Discussion
### Analysis of Volatile Organic Compounds
The relative percent area of all volatile compounds identified in fermented doughs is described in Table S3. The presence of 1-butanol, 3-methyl in all the samples except in SBC\({}_{\text{P}}\) was remarkable. The relative percentage of aldehydes varied between 23.09% and 58.84%, with the significant compounds within this group being hexanal in SBC\({}_{\text{P}}\), 2-heptenal in SB\({}_{1}\) and SB\({}_{2}\), and 2-nonenal in SBC. The relative percentage of esters varied between 15.31% and 42.76% and was higher in SBC, SB\({}_{1}\), and SB\({}_{2}\). Within this group, the most prominent compound was octanoic acid, ethyl ester, in the doughs mentioned. According to [PERSON] et al. [38], large concentrations of esters can begin to be detected only after 12 h of fermentation in sourdough. Therefore, in the sourdough studied, there was not enough fermentation time to produce compounds of this group, but there was in the 24 h fermentation of the doughs. Within the ketone group, there was an increase after fermentation in SBC\({}_{\text{P}}\) because of the increase in 3-octanone. [PERSON] et al. [44] suggested that this may be due to the fact that LAB fermentation leads to a higher production of ketones. Therefore, SBC\({}_{\text{P}}\), which presents a higher LAB content, showed a higher production of this group of compounds. A total of 37 VOCs were identified in the baked breads (Figure 3c), including acids (2), alcohols (6), aldehydes (16), alkanes (2), esters (6), ketones (3), and terpenes (2). The relative percent area of all volatile compounds identified in baked breads is described in Table S4. Usually, a 50% reduction in VOC content occurs during baking because many compounds volatilize [38]. The presence of aldehydes was mainly found, with their relative percentage between 69.81% and 91.49%. Within this group, the most prominent compounds were hexanal in all breads and 2-nonenal, which positively influenced the crust of sourdough breads [42]. [PERSON] et al. [41] also showed that aldehydes are the main VOCs in baked bread. Moreover, lipid oxidation reactions produce them in the crumb and are later transferred to the crust. The relative percentage of the rest of the groups decreased drastically. Therefore, to a lesser extent, the presence of alcohol in SB\({}_{1}\) and SB\({}_{2}\) stands out due to the content of 1-butanol, 3-methyl. This may be due to the fact that the organic acids produced by \(L\). _plantarum_ lead to proteolysis of the flour protein, releasing amino acids, which are aromatic precursors [38]. Within the esters group, they were not detected in the control bread but in the sourdough bread. Furthermore, those containing \(L\). _plantarum_ 5L1 showed a higher relative percentage. These compounds are related to the fruity odors of strawberries, pineapple, and bananas [45]. In [PERSON] and [PERSON] [46], a higher amount of alcohol and esters was also produced in sourdough bread fermented by a starter culture. In the case of acids, the propionic acid content in SBC\({}_{\text{P}}\) is notable due to the addition of propionate.