## 3 Results and Discussion
### Volatile Aroma Compounds Characteristic
Trans-2-undecenoic acid gives an earthy, fungal, fatty odor in meat samples and was found in different types of Korean dry-fermented sausages. [PERSON] et al. [2] reported a very strong correlation between the concentration of L-limonene in _Mucor_ fermented sausages, which also supports the results of our study [2,39]. Specific aroma compounds of fermented pork sausages were detected in traditional Chinese fermented foods prepared with the addition of different biostarters (Sx YCC3 strain and Lp MSZ2 strain). It was also described that the aroma profile of fermented sausage, with an addition of Sx YCC3 strain, contained, for example, trans-2-undecenoic acid, but they did not provide information on whether the Sx YCC3 starter contained _Mucor_ representatives; they mentioned only _Staphylococcus_ and _Acinetobacter_ representatives [2]. The are two classes of meat flavor precursors: the first one represents water-soluble components and the second one lipids. Aroma compounds during cooking are mainly formed due to the thermal degradation or oxidation of lipids and the Maillard reactions between reducing sugars and amino acids. The following substances, including sugars, amino acids, peptides, nucleotides, other nitrogenous components, and their other derivatives, are known as aroma compound precursors [41,42]. Cooked meat has been found to contain many volatile compounds resulting from lipid degradation, including aldehydes, aliphatic hydrocarbons, ketones, carboxylic acids, alcohols, and esters [42]. Moreover, other volatiles, such as oxygenated heterocyclic compounds, e.g., lactones and alkyl furans, have been identified in cooked meat samples [41]. As for the odor attributes, in the study by [PERSON] et al. [41] as well as in that by [PERSON] et al. [42], the authors claimed that, with a longer period of wet aging, the content of aroma compounds was higher, mentioning aldehydes and furans as aroma representatives. In our study, furans were not found. This finding might have been caused by the very low amounts of such compounds in our samples, but also by the chromatographic column that was used for the separation of the volatile compounds (Stabilwax). [PERSON] et al. [43] suggest that using non-polar phase for the separation of furans is better. In addition, [PERSON] and [PERSON] [12] underlined that _M. flavus_ growing on dry-aged beef gives off a nutty odor, while [PERSON] et al. [35] observed that, possibly due to the lack of visible mold growth on cuts of beef aged in different ways, palatability did not differ significantly. This study may confirm the significant effect which fungal microorganisms can have on enhancing or changing the flavor of beef. According to [PERSON] et al. [44], volatile compounds are substances of low molecular weight that are formed during lipid oxidation and Maillard reactions. Other researchers also indicate the importance of the interactions between Maillard reactions and lipid oxidation productsand the thermal degradation of thiamine in developing the appropriate aroma [45]. On the other hand, another study [30] reported that the largest group of compounds was the group of hydrocarbons, followed by alcohols and aldehydes. A higher amount of heptane and esters and unclassified compounds was found in dry-aged meat. The high index of heptane and hexanal in meat and their exposure to oxygen molecules became suitable factors for the auto-oxidation and/or thermal degradation of fatty acids, e.g., oleic acid, linoleic acid. This study indicates that the fungal strain used in the maturation process significantly influences the meat odor notes. Moreover, it is stated that the aroma profile of dry-aged beef with mold was significantly different from the meat samples that were dry-aged without it [3]. A total of 75 peaks were identified in the aroma profile of dry-aged beef with the fungal culture (within 30 min of chromatographic analysis), and only 67 peaks were identified in the samples without fungus (within 20 min of chromatographic analysis).