Comparative shelf life study and vitamin C loss kinetics in pasteurised and high pressure processed reconstituted orange juice

Shelf life of reconstituted orange juice after conventional thermal (80 degreesC, 30 s) or high hydrostatic pressure (500 M Pa, 35 degreesC, 5 min) pasteurisation was comparatively studied. Polypropylene bottles and laminated flexible pouches were used. Ascorbic acid loss, colour, viscosity and sensory characteristics were measured during storage at 0-15 degreesC. Ascorbic acid degradation rates were lower for high pressurised juice, leading to an extension of its shelf life compared to conventionally pasteurised juice. Kinetic modelling established a higher temperature dependence of ascorbic acid loss for high pressurised juice as expressed by activation energy values (61.1 and 43.8 kJ/mol respectively for high pressurised and thermally treated bottled juice). Based on ascorbic acid retention, the increase of shelf life of high pressurised juice stored in bottles compared to thermally pasteurised one ranged from 11% (storage at 15 degreesC) to 65% (storage at 0 degreesC). Respective values of shelf life increase for juices in pouches were 24% and 57%. Colour was not substantially affected by type of processing. Higher viscosity values were determined for high pressurised juice, while its sensory characteristics were judged superior. (C) 2003 Elsevier Science Ltd. All rights reserved.