Modeling of thermal effect in dynamic high-pressure microfluidization and its impact on heat sensitive components from fruit juice

Dynamic high-pressure microfluidization (DHPM) offers advantages in continuous liquid foods processing compared to traditional thermal processes. While generally recognized as a non-thermal technique, the short-duration thermal effects occurred during DHPM and their impact on heat-sensitive components remain unclear. This study simulated the physical changes in the core part of DHPM, quantified cumulative thermal effects based on a chromogenic model, and compared DHPM’s thermal impact with pasteurization or high-pressure processing under comparable conditions. Results revealed that the instantaneous flow velocity during fluid collision at 400 MPa reached as high as 420 m/s, with the localized temperature of up to 107 °C. When the cooling temperature was set to 25℃, the total thermal effects generated by DHPM at 200 and 400 MPa corresponded to 4.8 and 13.2 s, respectively, as 72 ℃ equivalent treatment. Significantly increased (p < 0.05) equivalent treating times were observed for DHPM at 400 MPa without cooling. Under the testing condition, DHPM caused significant degradation of ascorbic acid (31.9–44.2 %) and polyphenol oxidase (PPO) (20.7–38.4 %) alone, and synergistically enhanced PPO inactivation with the presence of ascorbic acid in water. Findings indicated that, based on the model systems in the present work, DHPM at elevated pressure (above 400 MPa) might pose comparable thermal effects as short duration pasteurization. However, its impact on heat-sensitive components was also determined by complex physical actions, such as shear forces and fluid collisions. The information delivered is useful to design optimal DHPM processing with minimal impact on vital nutrients.