## 3 Results and Discussion
### General Parameters and Phenol Content  
The protein and fat contents were not affected by the addition of synthetic additives or grape pomace (Table 1). The lack of effect of the pomace addition on them could be expected since it was added at low percentages and it had a low content of protein and fat (2.3 and 1.7%, respectively). This is in line with previous results comparing dry-cured sausages with a grape-seed-based extract vs. with sodium nitrite [18]. Conversely, the moisture content and the \(a_{w}\) and pH values were significantly different between the four dry-cured sausage groups (Table 1). The values for \(a_{w}\) and the moisture content (Table 1) were within the ranges previously reported in similar products [17; 18; 26]. Although relatively high, \(a_{w}\) was still below the 0.92 limit for ready-to-eat food established in the European Commission Regulation 2073/2005 [37] to prevent the growth of _Listeria_ spp. \(a_{w}\) was significantly lower in the pomace-added sausages than in the NITRASC group, similarly to the trend found for the moisture results (although [PERSON]'s test was not sufficiently powerful to reveal significant differences between groups). The pomace, despite being rich in water (69.2% [20]), was able to reduce the free and total water content. This effect might be related to the low pH of the pomace (3.96 [20]), which could have caused an immediate drop in pH, similarly to the pH drop reported when it was added at 0.5 and 3% to minced meat [20]. The low pH of the pomace might have favored an earlier protein denaturation and, consequently, a faster water loss at the beginning of the ripening stage. These lower values in \(a_{w}\) indicate that the pomace could accelerate sausage dehydration and shorten slightly the ripening stages that end when a fixed \(a_{w}\) or water loss is reached, although further research is required to confirm this result. There are no previous studies on the use of grape pomace to produce dry-cured sausages. Previous studies adding a grape-seed-based extract to dry-cured sausages reported no effect on the moisture content (\(a_{w}\) not researched) [17; 18], which suggests that the different composition of that seed-based extract and our pomace might differently affect water retention during ripening. The pH values (Table 1) were in the range defined by previous studies for most Mediterranean sausages [17; 18; 26; 38]. As shown in Table 1, the Control and 0.5%Pomace groups reached the highest values, and the NITRASC and 3%Pomace groups the lowest, which reveals that the differences in the final pH cannot be attributed solely to the low pH of the pomace. Usually, dry-cured sausages undergo a drop in pH during the earlier stages of ripening mainly due to the lactic acid bacteria (LAB) activity [39], and a later rise can also occur due to other microorganisms causing proteolysis and consuming the lactic acid previously generated [40; 41]. Our results suggest that the differences in pH might be related to a stimulation of LAB and/or an inhibition of proteolytic bacteria caused by the synthetic additives (nitrite and ascorbic acid in the NITRASC group) and the pomace added at 3%, but not at 0.5% (pomace at 3% was not sufficient to cause any difference from the Control group). With respect to the stimulation, it has been suggested that a grape-seed-based extract may favor the drop in pH by promoting the growth of _Lactobacillus_ during the first fermentation phase [18]. Regarding the inhibitory effect on proteolytic microorganisms, previous studies have reported antimicrobial activity in several components of grape pomace [6; 9] as well as the well-known antimicrobial effect of nitrites [1]. The phenol content was significantly different between the four groups, with the highest content in the Control and the 0.5%Pomace groups and the lowest in the NITRASC one (Table 1). The high values found in the Control group (without any grape pomace) suggest that a fraction of the compounds quantified as phenols were generated during sausage ripening.