Impact of infrared and dry air roasting on the oxidative stability, fatty acid composition, Maillard reaction products and other chemical properties of black cumin (Nigella sativa L.) seed oil

Authors: SURI, KANCHAN - Guru Nanak Dev University; SINGH, BALWINDER - Khalsa College; KAUR, AMRITPAL - Guru Nanak Dev University; Yadav, Madhav; SINGH, NARPINDER - Guru Nanak Dev University

Submitted to: Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/21/2019
Publication Date: 5/21/2019
Citation: Suri, K., Singh, B., Kaur, A., Yadav, M.P., Singh, N. 2019. Impact of infrared and dry air roasting on the oxidative stability, fatty acid composition, Maillard reaction products and other chemical properties of black cumin (Nigella sativa L.) seed oil. Food Chemistry. 295:537-547. https://doi.org/10.1016/j.foodchem.2019.05.140.
DOI: https://doi.org/10.1016/j.foodchem.2019.05.140

Interpretive Summary: Black cumin is an annual herb that is gaining popularity due to its unique nutritional properties and medicinal uses. It is emerging as a miracle medicinal herb due to its wide range of medicinal uses. Black cumin seed is also used as spice or flavor additive in a wide range of foods, such as pastry, cheese, bread, and pickles. Seeds of this plant contain a considerable quantity of oil (25-30%), which has been reported to have several health-promoting properties. The active ingredients with medicinal properties in the seeds are mainly concentrated in the oil. This oil is known for its antioxidant, anti-inflammatory, anticancer, antimicrobial and gastroprotective properties. These useful properties prompted us to extract oil from thermally treated black cumin seeds and study its properties. Thermal processing or roasting seeds before oil extraction facilitates the release of important oil constituents during the extraction process and increases oil yield. The present study has compared and evaluated the effect of dry air and infrared roasting (at 140, 160-and 180 degree Celsius for 5 and 10 min) on chemical characteristics, oxidative stability and fatty acid composition in black cumin seed oil. Dry air and infrared roasting of black cumin seeds at a higher temperature (160 and 180 degree Celsius for 10 min) significantly improved the quality of oils. In this study, we found that dry air roasting of black cumin seeds at 180 degrees Celsius for 10 min improved oil yield, oxidative stability, chlorophyll, and carotenoid content, and other useful properties. This study can be of great value to the Indian and US black cumin growers, agricultural and food processing industries.

Technical Abstract: This study was designed to investigate the influence of infrared (IR) and dry air (DA) roasting (at 140, 160 & 180 degree Celsius for 5 and 10 min) on black cumin seed (BCS) oil quality characteristics. The oxidative stability index (OSI), Maillard reaction products (MRPs) and, chlorophyll and carotenoid content were significantly increased (P=0.005),while acid value (AV), peroxide value (PV) and color parameters (-a* and b*) were decreased in the oil obtained from DA roasted (180 degree Celsius for 10 min) seeds. DA and IR roasting slightly affected the fatty acid composition (FAC) of BCS oils. Higher OSI (13.87 h) of DA roasted oils may be attributed to the higher content of hydroxymethylfurfural (HMF) in DA roasted oils (3.73 mg/kg) as compared to IR roasted oils (0.60 mg/kg) at 180 degree Celsius for 10 min. DA roasting at higher temperature was more effective than IR in improving the oil quality and OSI. The FTIR spectra showed minor changes in peak intensities with no observed peak shift in oils of BCS roasting at high temperature, justifying that oil is stable and acceptable. This study suggests DA roasting of BCS at 180 degree Celsius for 10 min improves oil quality and enhances oxidative stability.