This study aimed to reduce food waste of orange pomace through an improved vacuum dryer with two different normal (NorAtm) and controlled atmosphere (ConAtm) methods. N2 gas was injected into a vacuum chamber to control the drying atmosphere to limit the oxidation reaction. A Central Composite Design (CCD) optimization approach was applied with temperature and pressure levels of 45 to 85 ℃ with an interval of 10 ℃ and 40 to 80 kPa with a 10 kPa interval, respectively, for both drying methods. The parameters, including effective moisture diffusivity, total energy consumption, color indices (ΔL*, Δa*, Δb*, and BI), antioxidant capacity, total phenolic content, and ascorbic acid, were measured for all samples during the drying process. The results showed that the controlled atmosphere positively affected the drying rate (16% increase on average) and could reduce energy consumption (16% decrease on average). Also, in addition to achieving more antioxidant capacity (11% increase), the ascorbic acid was more stable (up to 200%) under the controlled atmosphere conditions. TPC changes were significant at the level of 0.05 just for temperature changes by NorAtm. On the other hand, the effect of vacuum on the Δa* was insignificant for both ConAtm and NorAtm, and the value of Δa* orange pomace dried by ConAtm was lower than NorAtm by about 27%.
