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A total of 33 compounds of bell pepper volatile oils were identified by gas chromatography and mass spectrometry (GC-MS) in the volatile dichloromethane extract obtained from Pakistani bell pepper (Capsicum annum L.), locally known as Shimla Mirch. The main constituents of the volatile oils of bell pepper (fresh and dried) were benzaldehyde (20.9-3%), 2-methoxy-3-isobutyl-pyrazine (20.4-9%), Z-β-ocimene (13-3%), 4-hydroxy-2,5-dimethyl-3(2H)-furanone (12.7-2.5%), and β-ionone (12.1-0.9%). Non volatile components of bell pepper 'Twingo' and Bell Pepper No. 1 (fresh and dried) were extracted with n-hexane and methanol. All extracts from solvent extraction and the volatile extract described above exhibited clear antioxidant activities at levels of 10-60 µg/mL in the 2,2-diphenyl-1-picrylhydrazyl/linoleic acid and β-carotene bleaching assays. The dried bell pepper 'Twingo' volatile oil inhibited 2,2-diphenyl-1-picrylhydrazyl activity by 70.95 ± 0.89%, at a concentration of 60 µg/mL. This study indicates that Pakistani bell pepper could be used to produce novel natural antioxidants as well as a flavoring agent in various food products.

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SUMMARY:In the current investigation the crude oil of Nigella sativa was extracted from seeds using hydraulic and screw pressing techniques. Different parameters were evaluated in order to find out the appropriate technique to enhance the physicochemical and functional-related characteristics of the extracted crude oil. Results showed that the acid and peroxide values were significantly lower in the screw pressed oil (SPO) than in the hydraulic pressed oil (HPO). The total phenolic content of the SPO was significantly higher than that of HPO. Evaluation of the oxidative stability using the Rancimat test showed that SPO recorded a much higher oxidative stability index (40.07 h) than HPO (0.51 h). The yield of the volatile oil fraction and its contents of thymoquinone isolated from the SPO were higher than that from the HPO. Biological evaluation revealed that the SPO had significantly higher antimicrobial activity than HPO against Listeria monocytogenes and Staphylococcus aureus at 40 µL/well. KEYWORDS : Crude oil; Functionality; Hydraulic pressing; Nigella sativa; Screw pressing RESUMEN: Mejoras potenciales de las características físico-químicas y funcionales del aceite de Nigella sativa mediante extracción con prensa de tornillo. En la presente investigación se extrajo el aceite crudo de Nigella sativa de las semillas utilizando técnicas hidráulicas y de prensado de tornillo. Se evaluaron diferentes parámetros para conocer la técnica apropiada que potencie las características fisicoquímicas y funcionales del aceite extraído. Los resultados mostraron que los valores de ácido y peróxido fueron significativamente más bajos en el aceite de presión con tornillo (SPO) que en el aceite prensado hidráulico (HPO). El contenido fenólico total del SPO fue significativamente mayor que el de HPO. La evaluación de la estabilidad oxidativa mediante Rancimat demostró que el aceite SPO tiene un índice de estabilidad oxidativa mucho más alto (40,07 h) que el HPO (0,51 h). El rendimiento de la fracción volátil y su contenido de timoquinona aislada del aceite SPO fueron superiores a los del HPO. La evaluación biológica reveló que el aceite SPO tenía una actividad antimicrobiana significativamente mayor que el HPO contra Listeria monocitogenes y Staphylococcus aureus a 40 μL/pocillo.