## 3 Results and Discussion
### Oxidative Stability Assessment
#### 3.3.4 Thiobarbituric Acid (TBA) Value  
Malondialdehydedehyde (MDA) is a very important aldehyde for meat products, which is formed during secondary lipid oxidation of polyunsaturated (1-3-propanediol) fatty acids and is the main indicator of lipid oxidation leading to the formation of rancid odours in small amounts. Several studies have found that a value of 2-3 mg MDA/kg is required for meat and meat products to be suitable for consumption [58]. Figure 6 shows the TBA values following supplementation of sausage formulas with bell pepper processing by-products (DRBPB and DYBPB) during the 20-day storage period compared to the control samples and sausage samples with added sodium nitrite. Figure 6: Effect of supplementing sausage formulas with bell pepper processing by-products on TBA value during 20 days of storage. Results represent the mean value of three independent analyses \(\pm\) SD indicated by the error bars. a–m \(t\)-test was used to compare significant differences between the values obtained for sausage formulas (both control and sausage samples supplemented with different doses of dried bell pepper processing by-products); data from the same day of analysis showing different exponents show significant differences (\(p<0.05\)). Significantly higher TBA values were recorded for the control samples (SC, SDC, and SSC) compared to the samples with added sodium nitrite, DYBPB, and DRBPB throughout the 20 days of storage. The doses of the DYBPB and DRBPB and the heat treatments applied significantly influenced the TBA values obtained throughout storage (Figure 6). Thus, with increasing doses of the DYBPB and DRBPB, the TBA values of the investigated sausage samples decreased. In addition, better results in terms of TBA values were recorded for sausage samples with the added DRBPB (0.419-3.134 mg MDA/kg) compared to those with the added DYBPB (0.457-3.554 mg MDA/kg). When comparing the TBA values obtained from the two heat treatments applied, lower TBA values were obtained in the smoked and scaled samples (0.419-3.337 mg MDA/kg) compared to the smoked and dried samples (0.422-3.554 mg MDA/kg). These significant differences (\(p<0.05\)) between the sausage samples analysed were recorded throughout the 20 days of storage. Comparing the TBA values recorded for the DCN and SCN sausage samples and the sausages samples with the addition of the DYBPB and DRBPB, it can be seen that for both smoked and dried and smoked and scaled samples, the DRBPB in doses that provide a polyphenic content level of at least 180 mg GAE/kg processed raw meat can replace sodium nitrite in meat products. Similarly, to replace sodium nitrite with the DYBPB in sausage formulae, a dose providing a level of polyphenic compounds of 270 mg GAE/kg raw processed meat is required. The TBA values of the sausage samples analysed up to day 10 of storage were below 3 mg/kg, suggesting that they were not affected by the oxidation and rancidity process. After 20 days of storage, samples of the DSDRBPB and SSDRBPB at doses providing a level of polyphenic compounds of at least 180 mg GAE/kg of raw processed meat recorded values below 3 mg MDA/kg, demonstrating that DRBPB protected sausage samples against oxidation and rancidity. When DYBPB was incorporated into sausage formulas at doses providing a polyphenic compound level of 270 mg GAE/kg processed meat, no oxidation and rancidity process was found to have occurred. Both DSDYBPB and SSDYBPB were protected against rancidity and oxidation by adding the DYBPB at a dose that ensures a polyphenic content level of 270 mg GAE/kg processed meat. Our results are in agreement with those reported previously [12] when the effect of tomato processing by-products on the oxidation of smoked and cooked sausages and smoked and dried sausages during storage for 20 days was investigated. A similar trend was also recorded by [PERSON] et al. [59], who studied the effect of adding cyaenne and red sweet bell pepper in different proportions (0.1, 0.5, and 2%) as a natural antioxidant on lipid oxidation inhibition.