# Volatile Organic Compounds in Breads Prepared with Different Sourdoughs
## 3 Results
### Volatile Organic Compounds of Bread
It is formed during heating, during which, two main types of reactions were found: caramelization and the nonenzymatic Maillard reaction. In particular, furfural is derived from Amadori compounds produced during the Maillard reaction [11; 47]. Heptanal ranged between 7.59 ng/g in S2 and 20.34 ng/g in S4, and different studies showed a concentration that ranged between 41 and 77 ng/g depending on commercial yeast used to prepare the bread or a range between 15.3 and 40.4 ng/g in the crumb of bread prepared with different quantities of yeasts and with different temperatures of fermentation [43; 48]. Finally, [PERSON] et al. [52] showed a concentration that ranged between 1 and 2 ng/g depending on the storage time of bread with an increase in this compound during storage, and it was derived from lipid oxidation and found in bread prepared with and without sourdough and in the crust and crumb of bread [47; 48]. This compound influences green, rancid, aldehyde, fatty, and grass odors with a perception threshold of 3 ppb in water [3]. Benzaldehyde ranged between 9.64 ng/g in S2 and 15.70 ng/g in S4. This concentration is in accordance with [PERSON] et al. [52], who showed a range of concentrations between 9 and 23 ng/g in bread at different times of storage. Furthermore, [PERSON] et al. [48] showed a range between 23 and 56 ng/g in bread prepared with different commercial yeasts; in another work, they showed a concentration that ranged between 15 and 79.8 ng/g depending on the quantity of yeasts and the temperature of fermentation. This compound is derived from lipid oxidation and fermentative reactions and is present in bread prepared with and without sourdough in the crust and crumb of bread. It influences almond, sweet, and cherry odors with a perception threshold in water between 350-3500 ppb [3; 48; 50]. The benzenedetaldehyde concentration ranged between 12.20 ng/g in S2 and 29.10 in S4. The result is in accordance with [PERSON] et al. [43], who showed a range of concentrations between 24 and 141 ng/g depending on the commercial yeast used for bread preparation, while [PERSON] et al. [48] showed a range of concentrations between 27.25 and 48.25 ng/g depending on the quantity of yeasts and the temperature of fermentation. This compound derives from the fermentation of the dough and the Maillard reaction during baking. Its odor is described as honey-like, and it might be an important aroma compound because of the relatively lower threshold perception in water (4 ppb); furthermore, it was identified in bread crust and crumb [3; 50]. The nonanal concentration ranged between 13.36 ng/g in S2 and 31.17 ng/g in S2. [PERSON] et al. [48] and [PERSON] et al. [43] showed a concentration range between 14.59 and 20.38 ng/g and 18 and 34 ng/g, while [PERSON] et al. [52] showed a concentration of approximately 2 ng/g. Finally, [PERSON] et al. [41] showed a nonanal concentration of 70 ng/g in bread made with 50% sourdough. This compound derives from fermentation and lipid oxidation; its odor is described as soapy, fruit, rose, citrus, and orange, and it has a very low perception threshold in water (1 ppb) [3; 47]. Acetic acid was the prevalent organic acid found and ranged between 91.40 ng/g in S2 and 173.81 ng/g in S3. This acid is produced by _Lactobacillus_ during fermentation by the heterofermentative pathway [3; 11], and it can be produced in the fatty acid synthase pathway in yeast cells, with yeast malonyl coenzyme A (CoA) as the substrate for fatty acid synthase [44]. The content of acetic acid influences the aroma of bread obtained by sourdough [42; 54]. The heterocyclic compounds were also found in the range between 39.74 ng/g (7.15% of total VOCs) in S2 and 79.09 ng/g (7.36% of total VOCs) in S4. The identified heterocyclic compounds were 2-pentylfuran and 2,3-dihydrofuran. The concentration of 2-pentylfuran ranged between 31.95 ng/g in S2 and 72.40 ng/g in S4. This value is higher than the range reported by [PERSON] et al. [48], [PERSON] et al. [43], and [PERSON] et al.