Production and characterization of palm oil microcapsules obtained by complex coacervation in gelatin/gum Arabic
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Palm oil is a carotenoid-rich natural compound, whose microencapsulation by complex coacervation may protect it against adverse conditions, allowing applications in food formulations for nutritional enrichment and natural pigmentation. Besides, since the coacervates are insoluble in acid pH of stomach, this undigested lipid is delivered slowly in the intestinal tract, which can help treatment of metabolic disturbs. Accordingly, this study intended to optimize palm oil microencapsulation by complex coacervation using gelatin and gum Arabic as wall materials. For this purpose, the effects of wall material concentration (WM) (2.5, 5.0, and 7.5% w/v), gelatin:gum Arabic ratio (G:GA) (1:2; 1:1; 2:1), and core:wall material ratio (C:WM) (75, 100, and 125%) on the encapsulation efficiency, particle morphology, and size distribution of microcapsules were investigated. Microencapsulation assays followed a factorial central design and, after coacervation, the microcapsules were freeze-dried. The highest values of encapsulation efficiency were obtained using G:GA = 1:1 or 2:1 with C:WM = 100%, whereas the WM concentration could vary from 2.5 to 7.5%. High concentrations of WM (7.5%) and G:GA = 2:1 hampered the formation of spherical or oval microcapsules. Microcapsules showed average diameter (D[4.3]) between 97 and 690 µm, with increasing concentration of WM and higher C:WM ratio contributing to formation of larger microcapsules. The G:GA ratio showed the highest influence on the particle size, with the 1:2 ratio resulting in smaller microcapsules. Practical applications: Palm oil is a significant source of antioxidants and other phytonutrients, and its microencapsulation may protect these bioactive compounds, enabling its use to nutritional enrichment of dry food formulations, at the same time as functioning as a natural pigment given the intense reddish-orange color of the oil. In addition, the microcapsules may slow down palm oil release in the gastrointestinal tract, since the coacervates are insoluble in acid pH of stomach, allowing this nutrient to achieve the ileum before being digested and help treatment of metabolic disturbs. Accordingly, microencapsulation of palm oil can be of great interest for food and pharmaceutical industries to develop controlled-delivery systems to encapsulate and slow down digestion of lipids, inducing modulation of satiety response.