Microorganisms and Some Quality of Red Grapefruit Juice Affected by High Pressure Processing and High Temperature Short Time

The aim of this study was to evaluate the effects of high pressure processing (HPP; 550 MPa/10 min) and high temperature short time (HTST; 110 A degrees C/8.6 s) on microorganism, ascorbic acid, total phenols, antioxidant capacity, color, enzyme activity, and rheological behavior in red grapefruit juice during 30 days of storage at 4 A degrees C. After HPP, the total plate count (TPC) and yeast and molds (Y & M) in red grapefruit juice were significantly decreased by 4.83 and 4.15 log cycles and showed to be microbiologically safe during storage. The activity of pectin methylesterase (PME) and peroxidase (POD) was only inactivated by 22.5 % and increased by 10.4 % by HPP, but completely inactivated by HTST. For all the other quality properties (such as total phenols, ascorbic acid, antioxidant capacity, color) except cloud stability studied in this article, their retention was significantly better in the HPP-treated samples than in the HTST-treated samples during storage, which were closer to natural grapefruit juice. A longer shelf life was observed in HPP-treated grapefruit juice compared to HTST-treated ones.