## 3 Results and Discussion
### Volatile Aroma Compounds Characteristic  
There is no doubt that volatile compounds, namely their quality and quantity, determine the sensory quality of the product. The results show that the samples aged with biostarter are characterized by significantly higher shear of aldehydes and acids compared to the control ones (Table 3, Figure 2). The samples aged with the biostarter are also characterized by a lower shear of alcohols, ketones, and hydrocarbons. The most abundant volatile compounds in the profile of samples aged with _Mf_ fungal biostarter are nonanal (43.9%), octanal (12.5%), heptanal (10.2%), hexanal (8.7%), and 1-octanol (6%), representing about 80% of the shear of all determined compounds (Table 3). The control samples are characterized by high amounts of aldehydes and alcohols. Moreover, ketones, acids, and hydrocarbons represented other groups of the most abundant chemical substances found in the profile. The most abundant volatiles determined in the beef control samples were nonanal (43.8%), octanal (11.1%), 1-octanol (7.1%), heptanal (6.8%), and 1-decanol (5.8%) (Table 3). The table shows that aldehydes are the most important group of volatiles found in beef samples with biostarters (83.8%) and control beef samples (70%) (Figure 2). Among alcohols, 1-octanol was found in the samples with the biostarter corresponding, respectively, to spicy notes [36], nutty, pop-corn like [37], citrus, aromatic [38]. Altogether, the obtained results suggest that dry-aging with _M. flavus_ biosstarter significantly enhances \begin{table}
\begin{tabular}{c c c} \hline \hline
**Trait** & **Control** & **Biostarter** \\ \hline Shear force after grilling [N] & 97.93  \\ Penetration force after grilling (mm) & 13.11  & 12.41  \\ \hline \hline \end{tabular} The results marked with the letters a, b are statistically significant (\(p<0.05\)).  
\end{table} 
Table 2: Instrumental assessment of beef hardness after 21 days of aging. Figure 1: Comparison of sensory liking (40 consumers) control and biostarter samples after 21 days of dry aging. Odor A—raw material (after 21 days of dry-aging; before heat treatment), Odor B—after heat treatment. Different letters (a, b) indicate means that are significantly different at the level of \(p<0.05\). the levels of particular aldehydes and esters, such as hexanal (fresh, green, fatty), heptanal (fatty, floral), pentanal (fermented, bread, fruity, nutty odor), hexyl ester of formic acid (fruity odor), and trans-2-undecenoic acid (mild odor), which represent compounds formed during lipid oxidation [8]. These flavors have often been used to describe dry-aged beef: beefy, buttery, nutty, and earthy [34]. [PERSON] et al. [39] reported that nonanal and hexanal are derived from the oxidation of linoleic acid and linolenic acid, and very high amounts of hexanal can lead to an off-flavor. Among the compounds detected in the current study, 2-nonenal, trans-2-undecenoic acid, 1,2-dimethyl-cyclopentane, and the following esters: formic acid hexyl ester, 4-methyl-pentanoic acid methyl ester, 10-undecenoic acid methyl ester, were found only in the samples aged with biostarters. According to [PERSON] [8], the most important aroma compounds in fermented sausages are aldehydes, especially hexanal (being the most significant aldehyde), followed by pentanal, octanal, and 2-nonenal (grass, green, herbal odors). In addition, [PERSON] et al. [5] described the volatile profile of dry and wet-aged beef. These authors reported that, in all samples, the highest amounts of volatile compounds were accounted for by hexanal, 1-octen-3-ol, and also 2-nonenal. However, other aldehydes were also found. However, it is worth mentioning that [PERSON] et al. [5] performed the GC analysis using a different chromatographic column (nonpolar InertCap I column) than the one we used (Stabilwax column). 1,2-dimethyl-cyclopentane was extracted from endophytic fungi isolated from _Bruguiera gymnorhiza_[40] and is also known as a volatile compound produced by _Mucor_ in meat products [2].