## 3 Results
### VOC Profile and Correlation Analysis
Figure 1: _Cont._  
Figure 1: Hierarchical cluster analysis on heatmap plot between strains and VOC profile, during storage of inoculated fish juice agar model substrates at 0 \({}^{\circ}\)C (a), 4 \({}^{\circ}\)C (b) and 8 \({}^{\circ}\)C (c). With respect to storage at 4 \({}^{\circ}\)C (Figure 1b), the models were divided into three main groups. More specifically, the first group included the control treatment throughout storage. This cluster was closely related the production of alcohols (e.g., ethyl alcohol, isopropyl1 alcohol, 1-penten-3-ol, 2-hexe-1-ol (trans), etc. ), aldehydes (e.g., nonanal, octanal, hexanal, etc. ), and ketones (e.g., 2-octanone, acetophenone, 2-hexanone etc.). The second group included mixed culture at the latest stages of storage (D 8 and D10). This group produced a specific VOC profile being strongly related to ketones (e.g., 2-heptanone, 2-nonanone, 2-pentanone, etc.) and aldehydes (e.g., 2-methylbutyldehyde, isobutyraldehyde), while the presence of 1-butanol, 2-methyl was also remarkable. Similarly, the third cluster, constituted mainly by all the remaining cases at D 8 and D 10, was characterized by similar ketone profiles to those in the second group; however, in this case, the production of aldehydes compared to that in the second group was negligible. The latter was the main reason for the separation between the second and the third cluster. On the other hand, at 8 \({}^{\circ}\)C (Figure 1c), there was not a clear separation between the initial (D 0) and the final stage of storage (D 4). In the context of this complexity, a clustered VOC group (i.e., limonene, nonanal, n-decanal, heptanal, 1-penten-3-ol, 2-ethyl-1-hexanol, 1-hexanol, isoamyl alcohol, etc.) exhibited a consistent profile throughout storage in both inoculated and non-inoculated models, while others (i.e, 2-octanone, ethane,1,2-diethoxy, isobutyraldehyde, 4-methyl-2-pentanone, 2-methylbutylaldehyde) were not linked with D 4, in any of the treatments. Furthermore, VOCs including methylene chloride and 2-ethyl-1-hexanol were linked with all storage days in all cases, exhibiting a higher correlation with the last day of storage (D 4). Similar findings were observed for n-nonane, although this compound had no correlation with the non-inoculated treatment at D 4. Furthermore, in the non-inoculated sample, a group of alcohols and ketones were highly linked with the initial and middle storage stages but not with D 4. A unique and/or strong correlation profile between some VOC and strains was observed at D 4. For example, strain 55 (Bacterium SBF-B18-dsp: _P. fragi_) was strongly correlated with 1-butanol-2-methyl, ethyl octanoate, disulfide dimethyl, 3-octanone and 2-undecanone, while strain 83 (_Pseudomonas_ sp. GSB-b11) was strongly related to ethyl myristate and 2-propanol-1-butoxy. In addition, strain 63 (_Pseudomonas fragi_ strain b67) was strongly linked with ethyl acetate, strain 35 (Bacterium SBF-B5-d0: _P. fluorescens_) with 2-hexen-1-ol, strain 45 (Bacterium SBF-B19-dsp: _P. fragi_) with 2-pentanone, strain 71 (_P. fluorescens_ strain b84) with octanal and n-butyl acetate, while the mixed inoculum was solely related to 3,4 hexanedione. Among the aforementioned treatments (strain 45 and mix) a well-shared ketone group (2-heptanone and 2-nonanone) with high correlation was also observed. Finally, it should be pointed out that strain 63 (_Pseudomonas fragi_ strain b67) was solely strongly related to a variety of unique VOCs, including ethyl-2-methylbutyrate, 4-hexene-3-one, ethyl tiglate, ethyl isovalerate and ethyl propionate. The VOCs that were increased only in inoculated models during storage (Figure 2) possessed a complex and strain-/temperature-dependent profile. At 0 \({}^{\circ}\)C (Figure 2a), methanethiol increased during storage in models inoculated with strains 35, 45 and 61, while dimethyl sulfide also increased by the same strains as well as strain 55.