This study explored the application of green ultrasound-assisted technology for the extraction of oil from the intestines of rainbow trout. Purification methodologies were incorporated using adsorbents in order to enhance the quality of the extracted oil, which was evaluated based on its color, peroxide value (POV), free fatty acids, organic pollutants, and fatty acid composition. The extraction condition for maximum oil recovery was 60 °C for 30 min, with the addition of 1 g of sodium chloride and a water-to-sample ratio of 0:2. The analysis indicated that silica gel exhibited the highest efficiency as an adsorbent for the elimination of peroxides from extracted oil, with optimal results achieved after adsorption for 60 min. Despite undergoing purification, the POV of fish oil still exceeded the quality standard established by the CODEX Alimentarius Commission. In order to optimize the extraction process, the incorporation of antioxidants, including gallic acid, tannic acid, and Aronia (black chokeberry) powder, was implemented before the oil refining process. The integration of antioxidants and purification further lowered the POV and mitigated the production of organic pollutants, concurrently enhancing oil quality compared to without antioxidants. Notably, the incorporation of antioxidants during the initial stages of the extraction process resulted in a significant increase in the average concentrations of essential polyunsaturated fatty acids (PUFAs) in the final products. Overall, this study revealed that Aronia has the potential to serve as a natural, less-costly antioxidant alternative to pure antioxidants, such as tannic acid and gallic acid. Furthermore, the potential nutritional value of the final refined oil sample derived from rainbow trout intestines can be improved in terms of ω-3 fatty acid content by the developed method.

This study aimed to investigate the occurrence of eight nitrosamines (NAs) in particulate (PM_2.5) and gaseous phases and assess the human health risk associated with these compounds in an urban area of Chuncheon, Gangwon State, South Korea, across four sampling seasons. The findings revealed that the total concentrations of eight NAs measured during the sampling period exceeded the public health recommendation of 0.3 ng/m³ provided by the Norwegian Institute of Public Health, indicating a potential human health risk from NA exposures. In particular, the average total NA concentration observed in the gaseous samples during the winter of 2021 was 18.1 ± 6.46 ng/m³. The primary emission sources could potentially impact the concentrations of NAs in the atmosphere due to their significant positive correlation with primary emission species such as NO₂, CO, and SO₂. Moreover, the levels of particulate NAs during the summer were negatively correlated with O₃, suggesting that their formation might be influenced by ozonation in the aqueous aerosol phase. In addition, the total NA concentrations measured in the gaseous phase were four to six times higher than those measured in the PM_2.5 phase throughout the sampling period. Thus, domestic sources have the potential to impact the pollution levels of the research area more significantly than long-range atmospheric transport. In particular, the highest concentrations of NAs in the gas phase were observed during the winter, while the lowest concentrations were recorded in the summer, possibly influenced by photolysis. Nevertheless, the study suggested that tertiary amines might contribute to the presence of gaseous NAs in sunlight. Consequently, further studies focusing on the occurrence of tertiary amines in the gas phase should be considered. The cumulative lifetime cancer risks estimated from inhalation exposure exceeded the acceptable risk level of 10^⁻6 for all age groups across all four seasons. Therefore, it is crucial to implement effective control measures to mitigate potential health risks associated with exposure to NAs.