Abstract

Sulforaphane (SFN) is an isothiocyanate considered to be health-promoting, but its instability and sensitivity to oxygen, heat and pH confine its utilization in Industry. The O/W emulsion method as a SFN microencapsulation process could be a solution to the low efficiencies obtained by other authors [2], due to the protection provided by the oily medium [1]. In addition, there are not stabilization studies of SFN for its inclusion into food. The purpose of this study was to investigate the microencapsulation of SFN using the O/W emulsion system with Gum Arabic (GA) as wall material; to evaluate the microencapsulation efficiency and yield of SFN; and to identify the microencapsulation conditions that maximize the efficiency and yield of SFN for its application in the food industry. The O/W emulsion method was analyzed using the response surface methodology to define and optimize the independent variables that affect the process using Statgraphics Centurion Version XV. Box–Behnken statistical design was used to optimize the system conditions (SFN/GA ratio, Tween 80 concentration (CT80) and agitation time), the effects were evaluated considering the variables separately and their interactions. The response variables were Yield, Efficiency and free SFN fraction. The components of system were Vaseline (oil phase), T80 (surfactant), SFN extract in ethanol obtained from broccoli seed (active component) and GA solution (20% w/w) (aqueous phase). The mixture was placed in a water bath while stirring at 8000 rpm at the temperatura 20°C and times (7, 11 and 15 minutes) in a homogenizer (T 25 D, IKA, Germany). The mixture was dehydrated in a vacuum oven (-0.6 MPa) at 37 ± 2°C for 24 h. The dried microcapsules obtained under optimal conditions were visualized by optical microscopy and their moisture and Aw were measured. The encapsulation efficiencies obtained in the Box-Beheken design was between 45-90%. The SFN/GA Ratio had a significant negative effect on efficiency and the CT80 had a positive effect on this response. Encapsulation yield fluctuated between 80-90% and showed not significant differences between the different treatments. The free SFN fraction varied between 10-43%, and was positively affected by CT80. The microcapsules presented a spherical shape with the presence of micelles around these, probably generated by excess of surfactant and free SFN. The O/W emulsion method with GA as wall material protects the SFN from the drying process. The addition of an oily medium and surfactants allows the formation of micelles with the free SFN, this could suppose a double microencapsulation. The inclusion of SFN microcapsules to food could be possible.