## 4 Discussion  
With regard to pH, the main differences coincided with processing stage, resulting from the proliferation of lactic acid bacteria (LAB) that normally takes place during product processing [3, 6, 9, 10], and the concomitant release of organic acids like lactic acid. Lactic acid is typically one of the compounds responsible for the pH decrease in dry-fermented meat products. When compared with \"Control\" products, those processed with LSF showed a less pronounced pH reduction, with this effect being particularly evident in products from Batch B. Since there were no differences in TVBN levels indicating the release of important amounts of nitrogen compounds, such as ammonia, that could explain the higher pH values measured in \"LSF\" products, these results suggest that the smoke condensate had a similar effect to that attributed by [PERSON] et al. [10] to salt addition. The use of this ingredient, particularly when it was directly added during seasoning, may have favored a greater extraction of the proteins that are responsible for a buffer effect and the lower pH decrease. In the light of current knowledge, the temperature, fermentation period, drying conditions, smoking and processing time are decisive factors that affect proteolysis dynamics. In this regard, nitrogen fractions, like NPN and TVBN, and the AA profile may provide important clues regarding proteolytic activity. The NPN is a good example, since it progressively increases during the dry-fermented sausage maturation as a result of this proteolytic activity. The NPN fraction includes the polypeptide and peptide nitrogen content, as well as AA and TVBN. As a result of the proteolytic activity that takes place during meat product fermentation, total AA increased with the processing time. Yet AA accumulated at a lower rate during product storage, which may be attributed to two different factors: (1) the AA formation has a feedback effect, negatively affecting aminopeptidase activity; (2) AA are further converted into other compounds [11]. Indeed, once in their free form, AA can follow several transformation mechanisms, where deamination and decarboxylation are included. Among the studied AA, alanine was the most abundant, despite its content remaining globally unchanged throughout processing and storage. In turn, arginine levels doubled when compared to their initial levels. The a\({}_{\text{W}}\) reduction is known to contribute to the inhibition of the enzymes involved in these AA releases, the alanylaminopeptides and arginylaminopeptides [12]. However, arginylaminopeptidase activity seems to be less impacted by lower a\({}_{\text{W}}\)[12], which might explain the higher arginine accumulation observed throughout processing and product storage. However, various trends have been reported in the literature regarding arginine content during meat product processing [6, 13, 14, 15], suggesting that multiple factors may be simultaneously affecting the release/metabolism of this AA. In fact, arginine is closely related to ornithine formation through the arginine deaminase pathway (ADI) [1, 16], which can further be converted to putrescine. Likewise, arginine can also be converted to agmatine and later on to putrescine. As such, the amounts of arginine will depend on the balance between these pathways. For example, [PERSON] et al. [13] observed a negative correlation between arginine and ornithine content. Our results, however, show a positive correlation between these two AA (r = 0.58, \(p\) < 0.05). In Batch A, the ornithine content increased proportionally to that of arginine, with the ratio arginine/ornithine being quite regular, between 2.49 and 2.21 (in the \"Control\" and \"LSF\" samples, respectively). A different scenario was found in stored samples from Batch B due to the ornithine decrease during storage, coinciding with a significant increase in putrescine amounts in later storage stages. Leucine and lysine are among those AA that increased the most during processing and product storage, in line with what was observed by [PERSON] et al.