## 3 Results and Discussion
### Polypphenols/Antioxidant Properties  
Red bell pepper fruits have been found to contain vitamin C, carotenoids, polyphenols, and other compounds that have been identified as being responsible for their antioxidant properties [66]. The ferric ion reduction assay (FRAP) is a method commonly used to assess the antioxidant capacity of antioxidants based on their ability to reduce Fe(III). Due to the complexity of antioxidant capacity in plant material, it is recommended that at least two different methods be used to assess antioxidant activity [67]. In the present study, three methods were used to obtain a more complete picture of the antioxidant properties of the samples tested. The total antioxidant capacity of bell pepper, as determined by the FRAP method, ranged from 3.30 mg TE/g d.m. to 4.58 mg TE/g d.m. (Figure 6). In this ultrasound, pre-treatment led, in most cases, to a reduction in antioxidant activity compared to untreated samples. However, the results indicate that process parameters such as ultrasonic time and intensity can influence the results. For example, increasing the ultrasonic treatment time using the immersion method to 30 min increased the antioxidant activity by about 11% compared to 15 min. In the ABTS test, the antioxidant activity in most fermented samples was not significantly different; the method used and its parameters had no apparent effect on the antioxidant activity. There was a slight increase in the antioxidant activity against ABTS+ of the fermented peppers with an increase in time (from 15 to 30 min) in the case of prior sonication by the immersion method; in the contact method, the highest ABTS+ scavenging capacity, i.e., 7.41 mg TE/g d.m., was achieved by the sample previously subjected to 5 min sonication. In the DPPH free radical scavenging method and the ABTS ion radical scavenging method, the antioxidant activity of red bell pepper was found to range from 0.94 mg TE/g d.m. to 2.41 mg TE/g d.m. (DPPH) and from 6.21 mg TE/g d.m. to 9.3 mg TE/g d.m. (ABTS), respectively. The variations observed in the results of these methods may be attributed to the differing sensitivities of each assay to specific bioactive compounds, such as polyphenols and vitamin C. Additionally, the assays demonstrated varying sensitivities to the polarity of the bioactive compounds, which may have further contributed to the discrepancies in results. Statistical analysis indicated that the treatment methods and their corresponding parameters significantly influenced free radical scavenging capacity. Notably, the three-minute ultrasonic contact treatment enhanced antioxidant activity against the DPPH radical by 42.1%. In the DPPH free radical scavenging method and the ABTS ion radical scavenging method, the antioxidant activity of the tested pepper fruits ranged from 0.94 mg TE/g d.m. to 2.41 mg TE/g d.m. for DPPH, and from 6.21 mg TE/g d.m. to 9.3 mg TE/g d.m. for ABTS. The observed variations in the results may be attributed to the differing sensitivities of the two tests to specific bioactive compounds, such as polyphenols and vitamin C. Additionally, the tests demonstrated varying degrees of sensitivity to the polarity of the bioactive compounds, which could explain the discrepancies in the findings [68; 69]. Statistical analysis indicated that the treatment methods and their parameters significantly influenced the free radical scavenging capacity. For example, an ultrasonic contact treatment lasting three minutes led to a 42.1% increase in antioxidant activity against the DPPH radical compared to the fresh sample. In contrast, lactic fermentation mainly resulted in decreased activity towards DPPH, although a lesser decline was also noted, albeit to a smaller extent than with DPPH. A review of the existing literature confirms the varying effects of non-thermal pre-treatment methods on the antioxidant activity of vegetables. [PERSON] et al. [70] demonstrated that the use of ultrasound before drying enhanced antioxidant activity in both FRAP and ABTS assays. Similarly, [PERSON] et al.