Enhancing dispersion stability of alpha-tocopherol in aqueous media using maize starch and ultrasonication

Abstract

Alpha-tocopherol (30-120 mg) was dispersed in an aqueous maize starch solution (0-240 mg starch solids in 30 mL) at various temperatures (60-80 degrees C) for 3 h, followed by cooling to 30 degrees C for different periods (0-12 h). The dispersion prepared under an optimized condition was subjected to ultrasonic treatment (up to 5 min in ice bath) to enhance the dispersion stability. When an aqueous a-tocopherol (60 mg) dispersion in a starch solution (120 mg in 30 mL) was prepared at 70 degrees C with cooling for 3 h and ultrasonic treatment for 3 min, a homogenous and opaque dispersion was obtained with 74% (w/w) of the a-tocopherol added was stably dispersed. The ultrasonic treatment decreased hydrodynamic diameter (from 1253 to 416 nm) and zeta-potential (from 6.28 to 22.40 mV) of the dispersed alpha-tocopherol particles, improving the dispersion stability. During a storage for 28 days at room temperature, the dispersion remained stable without producing any precipitates or aggregates. When the alpha-tocopherol dispersion in starch solution was subjected to autoclave treatment (121 degrees C for 20 min), 25% of the alpha-tocopherol in the dispersion was transformed to immiscible phase and phase-separated. (C) 2016 Elsevier Ltd. All rights reserved.