Research Information System
Thesis Type: Doctorate
Institution Of The Thesis: Eskisehir Osmangazi University, Fen Bilimleri Enstitüsü, Fen Bil.Enst.Md.Lüğü, Turkey
Approval Date: 2023
Thesis Language: Turkish
Student: SEDA DOĞAN
Principal Supervisor (For Co-Supervisor Theses): Pınar Aytar Çelik
Co-Supervisor: Temel Özek
Abstract:
In this study; Nigella sativa oil obtained by cold press extraction stored at different times and temperatures, N. sativa oil obtained by supercritical fluid (CO2) extraction stored at +4 ˚C, N. damascena stored at +4 ˚C obtained by cold press extraction Physicochemical properties, amount of thymoquinone, antioxidant and antimicrobial activities of the oil were compared. The antioxidant activities of the oils were determined by DPPH (diphenyl picrylhydrazil radical scavenging capacity), CUPRAC (CUPric Reducing Antioxidant Capacity) and total phenolic content analysis. Antimicrobial activities were evaluated by Disk Diffusion method and Minimal inhibition concentration test. 10 Pathogenic microorganisms were used in antimicrobial activity tests. While N. sativa oil could form zones of different diameters against 6 microorganisms, N. damascena oil could not form any zones against any microorganisms. While thymoquinone active substance was found in N. sativa oil at a rate of 1.90±0.05%, it was not detected in N. damascena oil. Initial peroxide values of N. damascena and N. sativa oil were determined as 0.36±0.02 meq O2/kg oil and 20.69±0.34 meq O2/kg oil, respectively. Total phenolic contents of N. damascena and N. sativa oils were found as 2245 mg gallic acid/kg oil and 235.45 mg gallic acid/kg oil, respectively. In the comparative analysis of the oil obtained by supercritical fluid extraction, it was seen that it was in the better groups statistically. It was determined that the thymoquinone amount of the oils was at the same rate in both methods. The optimum oil dose that can be added to the bread was determined by taking into account the sensory properties and technological properties of the bread product enriched with black cumin oil (N. sativa). It was determined that there was a decrease in the total number of bacteria, yeast and mold at the rate when N. sativa oil was added to the bread.