Effects of high hydrostatic pressure on the overall quality of Pêra-Rio orange juice during shelf life.

The effect of high hydrostatic pressure on antioxidant activity, total phenolic compounds, physicochemical characteristics, color, pectin methylesterase activity, and microbiological count were evaluated during the shelf life of Pêra-Rio orange juice. Pressurized (520 MPa, 60 ℃, for 360 s), non-processed and pasteurized (95 ℃/30 s) orange juice were compared at zero time of storage. Pressurized and pasteurized juices were studied during a refrigerated 90-day shelf life. Pressurization did not cause expressive change in physicochemical characteristics of Pêra-Rio orange juice along shelf life, but significantly reduced pectin methylesterase residual activity to 13% and microbiological counts below detection levels up to 68 days of storage, with small counts (30.0 × 10 CFU/mL mesophilic aerobic bacteria and 20.7 × 10 CFU/mL yeast and mold) at 90 days, capable of ensuring the juice's stability along shelf life. Lightness ( L*) and b* values were significantly reduced by high hydrostatic pressure during shelf life, while a* values were significantly higher. Ascorbic acid decreased around 80% during shelf life. Antioxidant activity remained stable after processing and during storage.