Microencapsulation of black cumin seed oil with hydrocolloids via spray drying

Nigella sativa is one of historical and miracle herbs been used for many centuries in different civilizations.  Although its oil provides high nutritious values of fatty acids and phytochemicals, the strong odor and peppery taste limits its application in food products.  In additions, the black cumin seed oil also poor solubility and rapid deterioration.  A wise strategy to enhance organoleptic property and promote oil solubility is encapsulating the cold press black cumin seed oil with suitable wall materials via spray drying.  In this study, eight water soluble hydrocolloids were used for formulating the mixed microcapsules.  Only four formulations of microcapsules were successfully spray dried including gum arabic alone (GA) or in combinations with inulin (GI), maltodextrin (GM), or whey protein (GW) at a ratio of 50:50.  The microencapsulation efficiencies (ME) of all microcapsules were ranged from 75 - 88%.  The ME of GI was superior to those of GM and GW, respectively.  Based on the SEM image, the smooth and spherical shape microstructure was obtained from the GI microcapsule (mGI).  The TQ, tertbutyl-hydroquinone (TBHQ), and longifolene were the main phytochemicals available in the mNSO powders, respectively.  Amounts of TQ and TBHQ encapsulated by the GA, GI, and GW were no significant difference.  Similar fatty acid profiles were observed in all microcapsules.  The solubilities of the mixed microcapsules (87-93%) were significantly higher than that of mGA (P < 0.05).  Also, the wettabilities of mGI and mGW (11 & 14 mins) were significantly faster than those of mGA and mGM.  Based on the DPPH assay for antioxidant activity of microcapsules, the % inhibition of mGI was the highest at all concentrations.  The cytotoxicity of mGI on Caco-2 cells was 182.5 µg/mL. The trained panelists could significantly distinguish sensory attributes of soybean milk and low fat cow milk containing 10 mg of TQ from mGI or NSO per serving size (P < 0.05).  The overall mean acceptability scores of each fortified milk products were mild to moderate (5.9 – 6.6) but no significant difference among the samples.  Therefore, the fortification of mNSO into health food products should be further study to improve acceptability and nutrition.