African palm oil (Elaeis guineensis Jacq.) is an oil that contains phytosterols, which are rich antioxidants that are capable of decreasing the intestinal absorption of cholesterol in the human body. Freeze-drying is a technique commonly used in the drying and powdering of encapsulated essential oils since its benefits allow the preservation of its physical and chemical properties. The phytosterols are of medical interest due to their potential to treat hypercholesterolemia. Therefore, this study attempts to optimize the drying process of canola oil with phytosterols using the lyophilization process. Water/oil solution (85.2%), maltodextrin/sodium alginate mixture (12.8%) and soy lecithin (2%) were used to prepare the emulsion. A surface response methodology was applied to determine the effects of water/oil and maltodextrin/sodium alginate mixture on the phytosterols encapsulation efficiency, water activity, solubility, and oxidative stability index on the produced lyophilized product. For the optimization, these physical-chemical attributes were evaluated as the dependent variables and the proportions of water/oil ratios and maltodextrin/alginate concentrations as the independent variables. An optimal treatment was determined with concentrations of 13.5 grams of maltodextrin, 1.5 grams of alginate, 84.2 ml of water, and 15.7 ml of oil. A predictive phytosterols content of 40 mg was obtained per gram of lyophilized product, an induction time of 33.15 hours in oxidative stability and solubility of 59.96%.
Keywords: Elaeis guineensis Jacq, lyophilization process, surface response, encapsulation, optimization.