Effect of high hydrostatic pressure processing and squeezing pressure on some quality properties of pomegranate juice against thermal treatment

The aim of this study was to investigate the effect of high hydrostatic pressure (HHP) treatment (200, 300, 400MPa; 5 degrees C, 15 degrees C and 25 degrees C; 5 and 10 min) on some quality properties of pomegranate juice. Juice samples are obtained under industrial conditions at two different squeezing pressure levels (100 and 150psi - 0.689 and 1.033MPa, respectively). Results are compared against conventional thermal treatment (85 degrees C/10 min) and raw sample. For all three processing temperature, HHP combinations at 400MPa for 10 min were sufficient to decrease the microbial load around 4.0 log cycles for both squeeze levels. All HHP treatments showed no significant decrease at antioxidant activity, total phenolic content and monomeric anthocyanin pigment concentrations, while there was a significant decrease (p.05) in thermal-treated samples. Being the highest sugar alcohol in pomegranate juice, mannitol content must be considered for determining the authenticity, and mannitol content increased with squeezing pressure and thermal treatment