Optimization of Spray Drying Process to Produce Microencapsulated Powders of Functional Extract Obtained from Red-Beet

Spray drying is one of the most important ways to prevent waste of strategic food products and their shelf life extension.Optimization of operating conditions involved in this system can be a suitable background to produce products with ideal physicochemical quality.
The effect of three operating parameters including inlet air temperature (IAT, 130-160°C), air flow rate (AFR, 2-4 m3/h) and feed flow rate (FFR, 4-10 mL/min) was investigated to attain the microencapsulated powders of red-beet extract containing functional pigment of betalain using RSM. The yield of produced powders, content of phenolic compounds and antioxidant activity of reconstituted extract were optimized.
The quadratic equations with high correlation coefficients (0.960-0.994) can well predict the optimal conditions to achieve the highest physicochemical efficiency. An increase in IAT and AFR had a significant effect on the decrease of the level of phenolic and antioxidant components of the obtained powders, while this trend led to an increase in the yield. The antioxidant and phenolic content of microencapsulated powders with low yield at higher FFRs are well maintained. The analysis of microscopy observations and particle size also confirmed the results clearly. The findings showed that the maximum physical yield (75%), phenolics content (1238.72 µg gallic acid/mL), and free-radical inhibition percentage (78.77%) can be obtained under the optimum conditions of 136.0°C IAT, 3.6 m3/h AFR, and 8.8 mL/min FFR.
Production of high-quality powders microencapsulating red-beet extract under the optimal conditions might be a beginning to develop fortification of food products with the obtained powders.