Process analysis and global optimization for the microencapsulation of phytosterols by spray drying

• Published in: Powder technology 2017-11, Vol.321, p.55-65
• Main Authors: Di Battista, Carla Agustina, Constenla, Diana, Ramírez Rigo, María Verónica, Piña, Juliana
• Format: Article
• Language: English
• Subjects: Air intakes; Air temperature; Atomizing; Desirability; Drying; Encapsulation; Flow rates; Global optimization; Independent variables; Inlet temperature; Intestine; Maltodextrin; Mathematical models; Microencapsulation; Microparticles; Optimization; Particle size; Phytosterols; Powder metallurgy; Process parameters; Response surface methodology; Retention; Solids; Spray drying; Spray forming; Statistical analysis; Surface response methodology; Variance analysis
• ISSN: 0032-5910; 1873-328X
• DOI: 10.1016/j.powtec.2017.08.008

The response surface methodology (RSM) was used to optimize the microencapsulation of phytosterols by spray drying. The independent variables were drying air inlet temperature, atomization air flowrate, feed flowrate, phytosterols and total solids contents and the mass ratio between wall materials (Arabic gum and maltodextrin). The analyzed responses were process yield, mean volume particle size of product microparticles, phytosterols retention and encapsulation efficiency. Statistical analysis revealed that the selected independent variables, especially the atomization air flowrate and feed phytosterols content, significantly affect the studied responses. Taking into account the observed results and the analysis of variance, all the responses were successfully adjusted to second order models with interactions, showing good R2 values and correlating the experimental data properly. The product microparticles were also obtained by using the predicted optimal operating and formulation variables to test the validity of the quadratic models. The experimental responses were found to be in agreement with the predicted values and were within the acceptable limits, indicating the suitability of the model for predicting key parameters related to process performance and product quality. The recommended optimal formulation and operating conditions for microencapsulation of phytosterols by spray drying are: drying air temperature of 160°C, atomization air and feed flowrates of 498L/h and 2.5mL/min (equivalent to 42mm of height of rotameter and 7% pump scale, respectively), phytosterols and total solids concentrations of 2 and 15g/100mL, respectively, and mass ratio between Arabic gum and maltodextrin of 2.06. The process yield, encapsulation efficiency and phytosterols retention obtained under the optimum conditions were 84, 72 and 76%, respectively. The product microparticles had a mean volume particle size of about 5μm, well below the more restricted upper size limit of 25μm required to guarantee the incorporation of PS into the intestine micellar phase. [Display omitted] •A Box-Behnken design of experiment was proposed to study microencapsulation by spray drying.•Phytosterols microparticles were successfully obtained.•Statistical models were appropriate to explain all the studied responses.•Phytosterols microencapsulation was optimized by using the desirability function.