Encapsulation of black rice bran anthocyanin-rich extract: optimization and characterization
2018
Bulatao, R.M. | Samin, J.P.A. | Eugenio, P.J.G | Salazar, J.R. | Monserate, J.J.
Anthocyanins are recognized for their health-promoting properties that could help reduce the risk of acquiring lifestyle-related diseases. Ranging from purple to blue, anthocyanins are considered to be an excellent source of natural colorants for food and pharmaceutical products. However, its utilization is restrained due to unstable properties upon exposure to light, high pH, and temperature. In this study, anthocyanins from black rice bran was encapsulated in chitosan-alginate through polyelectrolyte complex formation. Screening of factors and optimization were done using full-factorial design and Box-behnken design, respectively. The process of encapsulation involved ionic pre-gelation of calcium chloride (CaCl sub 2) with alginate followed by complexation with chitosan at different pH values. The encapsulated anthocyanins were further characterized for their encapsulation efficiency (EE), chemical properties, surface morphology, and particle size. Result showed that the optimum conditions for the encapsulation of anthocyanins were obtained by using 6.30 mg/mL chitosan and 36 mM CaCl sub 2 solutions at pH 5.5. This process had the highest EE of 51.2% among the combinations generated by response surface methodology. Furthermore, the developed capsules had high phenolic content (3.87 mg gallic acid eq./g) and strong antioxidant activity (5.69 mg Trolox eq./g). It also had smooth and round irregularly-shaped particles with 118.8 nm mean size. Therefore, it can be concluded that the encapsulated anthocyanins from black bran rice is a very promising material that could be used for food and pharmaceutical industries.
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