Retention Rate Enhancement of Antioxidant and Cyaniding 3-O-Glucoside Components of the Reconstituted Product from Spray-Dried Black Raspberry Juice by Optimizing Process Parameters

The effects of four operating parameters involved in the spray-drying process, including air inlet temperature (120-150 degrees C), air flow rate (3.5-5.0 m(3)/h), feed flow rate (2-10mL/min), and aspirator rate (50-70 m(3)/h), to produce black raspberry juice powders with the highest retention rate of healthy functional components were optimized using a response surface design. Second-order polynomial models with high R-2 (0.955-0.972) values were developed using multiple linear regression analysis. Results showed that the most significant (p < 0.05) process conditions that affected the antioxidant activity and cyanidin-3-O-glucoside content (C3GLU) of powders respectively were the quadratic effects of air inlet temperature and air flow rate and quadratic terms of air and feed flow rates. Laser diffraction particle size analysis and scanning electron microscopy were used to relate the microstructure and quality features. The lowest EC50 (0.0060 mL juice/g 1,1-diphenyl-2-picrylhydrazyl [DPPH]) and the highest C3GLU (4.721 mg/100 mL) values were achieved at an inlet temperature of 120.0 degrees C, air flow rate of 4.20 m(3)/h, feed flow rate of 8.65mL/min, and aspirator rate of 55.87 m(3)/h.