Performance of selected emulsifiers and their combinations in the preparation of β-carotene nanodispersions

In this work, the characteristics of beta-carotene nanodispersions prepared with sodium caseinate (SC), Tween 20, decaglycerol monolaurate (ML750) and sucrose fatty acid ester (L1695) using solvent displacement technique were compared. The mean particle size of the nanodispersions ranged from 30nm to 206nm, depending on the emulsifier used. SC-stabilized nanodispersions had the largest particles size, while those prepared with Tween 20 had the smallest. The mean particle size and size distribution of the nanodispersions generally remained unchanged after 8 weeks of storage time at 4 degrees C, but the beta-carotene content in all nanodispersions decreased over time. The beta-carotene in SC-stabilized nanodispersions was the most stable against oxidation among all samples, most likely due to the small specific surface area of the particles, physical barrier of SC protecting the encapsulated beta-carotene against free radicals and the antioxidative activity of caseins. The combined effect of SC and ML750 or L1695 on the mean particle size and beta-carotene retention was also investigated. Nanodispersions prepared with SC-ML750 or SC-L1695 showed larger mean particle sizes compared to those prepared with ML750 or L1695 alone. However, the stability of beta-carotene in these systems was improved owing to the antioxidative activity of SC. This work demonstrated the importance of emulsifier in determining the characteristics and stability of beta-carotene nanodispersions. (C) 2008 Elsevier Ltd. All rights reserved.