Optimisation of High Hydrostatic Pressure Processing of Pra Rio Orange Juice

The influence of high hydrostatic pressure (HHP) on Pra Rio orange juice was investigated using response surface methodology. A central composite design was used to evaluate the effects of three processing conditions (independent variables), namely pressure (100-600 MPa), temperature (30-60 A degrees C) and time (30-360 s), on the native microflora and pectin methylesterase (PME) activity of orange juice. Analysis of variance showed that second-order polynomial models fitted well with the experimental data for PME residual activity (R (2) = 0.9586, p < 0.001) and aerobic microorganism count (R (2) = 0.9879, p < 0.001). The optimum HHP processing conditions to produce orange juice with PME residual activity of less than 20 % and low microorganism count (< 2 log cycles CFU/mL) were 550 to 600 MPa, 55 to 60 A degrees C and 330 to 360 s.