Oils derived from non-traditional seeds, such as safflower, milk thistle, and black cumin seeds, have recently grown in popularity. Seed oil is in high demand due to consumer interest in illness prevention and health promotion through healthier diets that include a high concentration of monounsaturated and polyunsaturated fatty acids and antioxidant phenolic components. This study assessed the quality characteristics of cold-pressed seed oil at three unique storage times: at the beginning of the trial (i.e., before storage), after 2 months, and after 4 months. The results of the performed analyses indicate that the acidity of extracted black cumin, safflower, and milk thistle seed oil fluctuates considerably over time. The highest acidity level change was detected for black cumin seed oil, from 10.26% after the extraction to 16.96% after 4 months of storage at 4 °C. Consequently, changes between pre- and post-storage peroxide concentrations were discernible after four months. Peroxide value in milk thistle and safflower seed oils increased by 0.92 meq/kg and 2.00 meq/kg, respectively, during the assessed storage time, while that of black cumin was very high and fluctuated. The storage period substantially affects oxidative changes and the oxidation stability of the oil. Major changes were observed in the polyunsaturated fatty acids in seed oil during storage. The essential changes were detected in the black cumin seed oil odor profile after 4 storage months. Their quality and stability, as well as the nature of the changes that occur during the storage of oil, require extensive investigation.

This study aimed to evaluate the effects of different pretreatment methods on the yield and chemical composition of Nigella sativa L. (i.e., black cumin) cold-pressed oil. Different pretreatment methods used included convection heating, microwave, ultrasound and pulsed electric fields (i.e., PEF); we investigated their effects on key parameters, including oil yield, fatty acid composition, total phenol and flavonoid content, peroxide value, acidity and antioxidant activity. However, no single pretreatment method was found to be better than all others. Instead, ultrasonication and pulsed electric fields (PEF) showed significant advantages. Ultrasonication showed the highest total phenolic content and improved oxidative stability, while PEF improved flavonoid content and antioxidant activity. Therefore, these findings suggest that a combination of several pretreatment options should be considered depending on specific industrial goals related to quality improvement and sustainability. This research also contributes to the existing knowledge on Nigella sativa L. oil processing and provides additional insights for optimizing extraction technique.

This study evaluates the effects of four pretreatment methods: convection heating, microwaving, ultrasonication, and pulsed electric fields (i.e., PEF), on the chemical composition, color profile, functional properties, phenolic profile, antioxidant activity, fatty acid composition, and protein content of Nigella sativa L. (i.e., black cumin) cold-pressed cake. Seeds were subjected to each pretreatment prior to cold press extraction. Microwave, ultrasonication, and pulsed electric field pretreatments produced the lowest press cake yields (63.61–65.54%), statistically equivalent to one another. Also, the microwave-treated and control samples retained the highest protein content on a dry matter basis (30.81 and 30.79 g·100 g⁻¹, respectively). Ultrasonication yielded the highest total phenolic and total flavonoid contents. Analysis of the press cake identified salicylic acid and catechin as the predominant bioactive compounds, suggesting potential antimicrobial and antioxidant applications. These findings provide evidence-based guidance for selecting Nigella sativa L. seed pretreatment strategies that at the same time optimize cold press oil extraction and the nutritional, functional, and bioactive value of the residual press cake. Thus, supporting its utilization as a sustainable by-product for food and feed applications.