Investigation of the stability and homogeneity of Nigella Sativa oil-in- water emulsion N.A. Shukri a,b,⇑ , M.U. Wahit b , F.F. Hilmi b , S.N.K. Othman c a Malaysian Nuclear Agency, Radiation Processing Technology Division, Bangi 43000, Kajang, Selangor, Malaysia b Faculty of Engineering, School of Chemical and Energy Engineering, Universiti Teknologi Malaysia, 81310 Johor Bahru, Johor, Malaysia c Faculty of Science and Technology, Universiti Sains Islam Malaysia, Bandar Baru Nilai, 71800 Nilai, Negeri Sembilan, Malaysia article info Article history: Available online 9 July 2020 Keywords: Oil-in-water emulsion Nigella Sativa Stability abstract In this study, the emulsion stability of Nigella Sativa (NS) emulsion in the presence of Tween 80 (T80) as surfactant at concentration range from 0.25 wt% to 3 wt% was carried out. The effectiveness of T80 for producing stable NS oil-in-water emulsion was characterized in terms of their creaming index, phase sep- aration and fourier transform infrared spectroscopy (FTIR). Results showed that the lowest concentration (0.25 wt%) of surfactant was not enough to avoid phase separation during emulsification while the high- est surfactant concentration (3 wt%) shows no obvious different with 2 wt% of T80. NS oil-in-water emul- sion containing 2 wt% of T80 concentration showed the optimal parameters with the longest stability of 24 h and demonstrated 0% creaming index of emulsion. In addition, the FTIR spectra showed the trans- mittance peak at 1746 cm À1 and at 1599 cm À1 of NS/T80 was shifted compared to NS alone, indicating the interaction between NS and T80 via changing of hydrogen bond. This study provides valuable infor- mation into the effect of surfactant concentration for producing stable NS oil-in-water emulsion with sig- nificant stability properties, which potentially useful for the formulation of food-based products. Ó 2019 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of 4th Advanced Materials Conference 2018, 4th AMC 2018, 27th & 28th November 2018, Hilton Kuching Hotel, Kuching, Sarawak, Malaysia. 1. Introduction Nigella Sativa (NS) or black seed oil is a well-known medicinal plant for traditional medicine system as well as a spice and food preservative. This plant commonly grows in the Middle East, East- ern and Western Europe and Central Asia. The NS seed are black in colour and taste slightly bitter. Nutritional investigation on NS showed that they are a good source of sodium, zinc, calcium, iron, magnesium, copper, potassium and copper [1]. Previous studies of NS have investigated the constituent in vitro and in vivo pharma- cological effect. The NS seed constituents exhibited remarkable therapeutic properties including antioxidant, anti-parasitic, anti- cancer, antimicrobial, anti-inflammatory, analgesic and antipyretic properties which have been related to its active principles such as thymol, carvacol, negillicine, nigellone, nigellidine, nigellimine-N- oxide thymohydroquinone, thymoquinone, dithymoquinone and a-hedrin [2]. Moreover, some study have clearly demonstrated the antimicrobial activity of NS against Escherichia coli, Bacillus sub- tilis, Streptococcus faecalis, Staphylococcus aureus, Pseudomonas aeruginosa and the pathogenic yeast Candida albicans [3,4]. There- fore, it is suitable to be used as an additive for the development of active packaging for food application. Production of an active packaging system by incorporation of NS into the packaging mate- rial may help in extension of shelf-life of the food product via inhi- bition of fungi growth in the food. Although it is known that the essential oils such as NS have potential antimicrobial and antifungal activity, due to the interac- tions between the components of essential oils and the food ingre- dients, the antimicrobial performance of essential oils in food system is lower than that of in-vitro [5]. As a solution, increasing stability of essential oils in film may help in an improvement of antimicrobial effect of active packaging system. To improve the emulsion stability of essential oil in formation of active packaging, a Tween 80 (T80) was selected as a surfactant. Tween surfactant comprise of fatty acid esters of polyethyelene-glycolated sorbital, with low critical micellar concentrations (CMC = 0.012 mM) and hydrophile-lipophile balance (HLB) values above 14, making it https://doi.org/10.1016/j.matpr.2020.05.692 2214-7853/Ó 2019 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of 4th Advanced Materials Conference 2018, 4th AMC 2018, 27th & 28th November 2018, Hilton Kuching Hotel, Kuching, Sarawak, Malaysia. ⇑ Corresponding author. E-mail address: azwin@nm.gov.my (N.A. Shukri). Materials Today: Proceedings 29 (2020) 58–62 Contents lists available at ScienceDirect Materials Today: Proceedings journal homepage: www.elsevier.com/locate/matpr