## 3 Results and Discussion  
### PH, a\({}_{w}\) (Water Activity,) and Microbial Counts  
Caviar analyzed in this study was associated with pH values ranging from 5.78 to 6.46 and a\({}_{w}\) values ranging from 0.954 to 0.985, comparable to those reported by [PERSON] et al. [22] for fish roes coming from various species, included sturgeon. Since these values are known to be sufficiently high to support the growth of some microbial species, an initial low microbial load and a strict control of hygiene and sanitation measures are considered to have a primary importance in managing eventual contamination during the entire process of caviar production [23]. Actually, even when microbiologically sterile eggs are aseptically removed from fish, a secondary contamination during the production could occur, since this kind of product requires broad handling and multiple processing procedures [22; 24]. Generally, the OAM and BSM series showed higher pH values for every sampling point when compared to salt samples. OAM and BSM samples ranged from 6.12 to 6.42, while the salt samples showed pH values always < 6, ranging from 5.84 to 5.97. As reported in Table 2, the TVC recorded in this study at t0 showed very low values, always < 2 Log CFU/g in all the analyzed series, without any significant difference. Similar values recorded at t0 for the TVC in all three series suggested that, even if initial slightly different levels of microbial counts could be present because of individual fish characteristics, the processing conditions in the production plant were adequately standardized and effective in controlling the contamination. The microflora detected in this study was mainly composed of Bacilli and halophilic bacteria (data not reported), due to the natural microbial strains selection that occurred in the product related to the addition of salts. Starting from t1, the TVC of the NC series showed a gradual increase, reaching average values up to 5.89, 5.90, and 6.89 Log CFU/g at t1, t2, and t3, respectively. The threshold limit of 6.0 Log CFU/g, frequently taken into consideration to designate the end of the shelf life of a fish product, was only recorded in the NC series at t2 and t3, corresponding to 8 and 14 months of ripening, respectively. In a previous study, [PERSON] et al. [25] found that white sturgeon caviar treated with 3-3.75% of salt and stored at refrigeration temperatures (3-7 \({}^{\circ}\)C) reached the total microbial count of 6.0 Log CFU/g in a time range of only 5-10 days. This outcome evidenced that the strictly low temperature (\(-2\)\({}^{\circ}\)C) sustained in the production plant for caviar analyzed in this study had a fundamental role in maintaining the food safety requirement for the NC product even in a longer term. Extended results for each replicate and additional data for Table 2 have been provided as Supplementary materials (Table S1 of Supplementary materials). The results obtained in this study about caviar's hygienic parameters can be considered positive, since the general picture regarding food safety of caviar and fish roes available in the literature is variable. As a matter of fact, a suitable hygienic level of processed fish roes from various species, including sturgeon, have been recently evidenced, with the limit of 6 Log CFU/g rarely exceeded in this kind of product [14; 26]. On the contrary, other authors had previously detected higher microbial counts in both caviar [23] and other fish roes products [27], in the range 3-6.5 Log CFU/g. The fact that in this study we found the highest microbial counts in NC samples supports the theory that salting in low concentration alone cannot be a sufficient step to inhibit completely the microbial growth in fish roes products if the shelf life is extended beyond 8 months [22]. Actually, in the OAM and BSM series, the TVC detected, very low since t0, did not show any relevant increase until the end of the study, showing a significant (\(p<0.05\)) difference from the TVC detected in the NC at t1. At the end of the sampling time