Processing Frozen Concentrated Orange Juice (FCOJ) by High Pressure Homogenization (HPH) Technology: Changes in the Viscoelastic Properties

The rheological properties of a fluid have an important role in process development and optimization. Due to its high concentration, frozen concentrated orange juice (FCOJ) shows viscoelastic behaviour, especially at low temperatures. In this study, high pressure homogenization (HPH) processing (0, 25, 50, 75, 100 and 150 MPa) was used to change the viscoelastic properties of FCOJ. The rheological behaviour of the FCOJ, before and after HPH processing, was evaluated using dynamic frequency sweep procedures. The storage (G') and loss (GaEuro(3)) moduli were modelled as a function of the oscillatory frequency using the power law. The sample processed at 0 MPa showed G' > GaEuro(3). On the other hand, all other samples presented GaEuro(3) > G'. Both the elastic and viscous behaviours decreased with increasing homogenization pressure. The power law parameters were then modelled as a function of the homogenization pressure using exponential functions. Also, the Cox-Merz rule was verified for all the samples, showing good applicability when a linear mathematical modification was applied. The reduction in the elastic and viscous components was explained by the reduction in particle size and molecular size of the serum constituents. A decrease in viscoelasticity leads to less resistance to flow and therefore to lower energy costs for the FCOJ process. These results are useful to understand the phenomena leading to an industrial application of this technology.