Supercritical CO2 Drying of Red Bell Pepper

Abstract

Supercritical CO2 food drying technique was investigated on red bell pepper with a lab-scale reactor equipped with CO2 recirculation. Box-Behnken design was used as experimental design to analyze the impact of temperature (313-333 K), pressure (10-14 MPa), CO2 flow rate (80-220 kg/h), and treatment time (6 and 16 h) on the final water activity. The results demonstrated that temperature was the most influential variable, reaching the lowest value of water activity (a(w) = 0.262) at 333 K, 12 MPa, and 100 kg/h. Efficient drying with a similar final water activity could be achieved at the lowest temperature considered (313 K) and longer drying time (16 h) with an appropriate combination of pressure (14 MPa) and flow rate (160 kg/h). Sc-CO2 samples showed similar values of color changes compared with freeze-dried samples with main differences corresponding to the "a" and "b" axes, i.e., in red and yellow. Textural properties of Sc-CO2 dried samples were not statistically different compared with freeze-drying. Sensory evaluation showed promising evidence for the use of supercritical CO2 as an alternative drying method to produce dried bell pepper products.