## 4 Discussion  
The objective of this study was to gain deeper knowledge about the quality of three salmon-based products and to compare the effect of the manufacturing process on their microbial ecosystem, organoleptic properties and volatilome. After the packaging step, the TVC counts were 4.0, 3.0 and <1.7 log CFU/g for the SG, MAP CSS and VP CSS, respectively. Such initial bacterial loads are usually found in lightly preserved salmon products [3; 4; 5; 6; 9; 14; 15; 16; 17; 18; 19; 20; 21; 22; 23; 24; 25; 26; 27; 28; 29; 30; 31; 32; 33; 34; 35; 36; 37; 38; 39; 40; 41; 42; 43; 44; 45; 46; 47; 48; 49] but may sometimes reach 5-6 log CFU/g depending on the raw material and smokhouse hygien quality [4; 6; 10]. The difference within the product was more likely due to the smoking process rather than the salt concentration, which was lower in the less-contaminated product (2.58 \(\pm\) 0.05, 3.05 \(\pm\) 0.12 and 2.17 \(\pm\) 0.28 NaCl/100 g flesh for the SG, MAP CSS and VP CSS, respectively). Phenolic compounds are known to possess antimicrobial activity [45] and are responsible for bacterial growth delay or inhibition in CSS [46; 47; 48; 49]. In this study, the total phenolic compounds were much more concentrated in the MAP and VP CSS (28 \(\pm\) 1 and 35 \(\pm\) 5 mg/kg of flesh, respectively) than what is usually found in CSS (often < 10 mg/kg). The lower phenolic concentration in MAP CSS compared to VP CSS may explain the higher initial bacterial count in the MAP CSS. This may also be explained by the supplementary cutting step to obtain dices, which was probably responsible for the recontamination before packaging, especially by Enterobacteriaceae (Figure 1). On day 0, the three products' microbial ecosystems were relatively close in the proportions of _Photobacterium_, _Lactobacillus_ and _Lactococcus_, accounting for about 50, 30 and 10% of the composition, respectively. Despite an overall compositional similarity, the SG ecosystem diversity was initially higher than the smoked products and remained so until 28 days. The diversity may be explained by the spices and herbs used for the SG preparation and the absence of selective pressure due to smoke. There were 20 OTU specific to  
Figure 8: Multidimensional representation of the three products, namely, SG, MAP CSS and VP CSS, at three sampling time points using the various blocks of data collected by means of the ComDim method. (**A**) Projection of individuals in dimensions 1 and 2, (**B**) projection of individuals in dimensions 2 and 3. Numbers associated with the sample name correspond to the sampling date in days. the SG and belonged to the bacterial and archaeal kingdom. Among them, _Shewanella_ (_S. putrefaciens_, _S. vesicusola_, _S. morhuae_, _S. baltica_, _S. frigiddimarina_), _Hafnia_ (_H. alvei_), _Weissella_ (_W. confusa_, _W. viridescens_, _W. kandleri_), _Staphylococcus_ (_S. equorum_) and _Bacillus_ are ubiquitous bacterial genera that were isolated from a wide variety of ecological niches, including seafood [3; 6; 9; 13; 14; 17; 18; 19; 50; 51; 52; 53; 54; 55; 56; 57; 58]. On the other hand, for some ecological niches, _Duganella_, _Terribacillus_, _Spealeococcus_, _Comomonas_, _Sphingobacterium_, _Brevbacterium_, _Halorubrum_ and _Halohasta_ are relatively unknown and not frequently described. Table 3 summarizes some ecological origins of these uncommon bacteria or archaea. Some were isolated from a specific ecological niche (e.g., _Halohasta_ and _Halorubrum_ in salt) but others are ubiquitous and can therefore be brought with the spices used for the SG preparation. Next-generation sequencing techniques are powerful tools for pinpointing minor microbial populations within ecosystems, which is information that is otherwise inaccessible using common cultural methods. For instance, [PERSON] et al. [17] also detected _Sphingobacterium_ sp. and _Brachybacterium_ sp. in diced bacon and _Comomonas_ sp. in cod and salmon fillets with pyrosequencing technology, although no isolate was collected.