Production of orange juice concentrate using conventional and microwave vacuum evaporation: Thermal degradation kinetics of bioactive compounds and color values

This study aimed to concentrate orange juice using the microwave vacuum evaporation (MVE) and the rotary evaporation (RE) at different absolute pressures (20, 31, and 47 kPa) and investigate the effects of two different concentration techniques on the degradation kinetics of vitamin C, total phenolic content (TPC), total carotenoid content (TCC), and color values. The MVE significantly raised the evaporation rate compared to the RE (p < .05). It was determined that the MVE and the RE at 80℃ required concentration-time 21 and 42 min, respectively. Total soluble solid changes during the MVE and the RE processes were fitted to six different empirical models with an R2 range between 0.915 and 0.998. The results showed that degradation rate constants for vitamin C, TPC, and TCC of orange juices concentrated using the RE were higher significantly than the MVE (p < .05). It was determined that the degradation rate constants of the L*, a*, b*, and ΔE orange juices concentrated using MVE were lower than the RE (p < .05). Novelty impact statement Orange juices were concentrated using MVE and RE. The MVE significantly increased the evaporation rate compared to the RE. The MVE protected bioactive compounds (values vitamin C, TPC, and TCC) and color values (L*, a*, b*, and ∆E) in comparison with the RE.