Effect of operating parameters on the physical and chemical stability of an oil gelled-in-water emulsified curcumin delivery system

This study was supported by the TEP025 'Technologies for Chemical and Biochemical Processes' Research Group from the Chemical Engineering Department of the University of Granada. We thank Professor Angel Delgado, from the Applied Physics Department, who made the Mastersizer 2000 available whenever we needed it. The research was funded by the Spanish Ministry of Education, Culture and Sport, via grant FPU17/03005 given to Mr Vellido-Perez, and the University of Granada through the program `Precompetitive Research Projects for Young Researchers 2018-Modality B' with the project entitled 'Design and development of stable oleogelified structures for vehiculization and protection of curcumin' (PPJIB2018-24).BACKGROUND Curcumin is a natural antioxidant with important beneficial properties for health, although its low bioavailability and sensitivity to many environmental agents limits its use in the food industry. Furthermore, some studies mention a potential synergistic effect with omega-3 polyunsaturated fatty acids, comprising other bioactive compounds extremely unstable and susceptible to oxidation. A relatively novel strategy to avoid oxidation processes is to transform liquid oils into three-dimensional structures by adding a gelling agent and forming a self-assembled network that can later be vectorized by incorporating it into other systems. The present study aimed to design and optimize an oil gelled-in-water curcumin-loaded emulsion to maximize curcumin stability and minimize lipid oxidation in terms of some critical operating parameters, such as dispersed phase, emulsifier and stabilizer concentrations, and homogenization rate. RESULTS The operating conditions that had a significant effect on the formulation were the dispersed phase weight fraction affecting droplet size and total lipid oxidation, homogenization conditions affecting droplet size and primary lipid oxidation, and emulsifier concentration affecting droplet size (significance level = 95%). The optimal formulation for maximizing curcumin load and minimizing lipid oxidation in the oleogelified matrix was 140.4 g kg(-1) dispersed phase, 50.0 g kg(-1) emulsifier, 4.9 g kg(-1) stabilizer and homogenization speed 1016 x g. CONCLUSION The results obtained in the present study provide a valuable tool for the rational design and development of oil gelled-in-water emulsions that stabilize and transport bioactive compounds such as curcumin.'Technologies for Chemical and Biochemical Processes' Research Group from the Chemical Engineering Department of the University of Granada TEP025Spanish Ministry of Education, Culture and Sport FPU17/03005University of Granad