The effects on orange juice batch pasteurization in an improved pilot-scalemicrowave (MW) oven was evaluated by monitoring pectin methyl-esterase (PME) activity, color, carotenoid compounds and vitamin C con- tent. Trials were performed on stirred orange juice heated at different temperatures (60, 70, 75, and 85 ◦ C) dur- ing batch process.MWpilot plant allowed real-time temperature control of samples using proportional integrative derivative (PID) techniques based on the infrared thermography temperature read-out. The inactivation of heat sensitive fraction of PME, that verifies orange juice pasteurization, showed a z-value of 22.1 ◦ C. Carotenoid content, responsible for sensorial and nutritional quality in fresh juices, decreased by about 13¯terMWpasteurization at 70 ◦ C for 1 min. Total of 7 carotenoid compounds were quantified during MW heating: zeaxanthin and β-carotene content decreased by about 26%, while no differences (P < 0.05) were found for β-cryptoxanthin in the same trial. A slight decrease in vitamin C content was monitored after MW heating. Results showed that MW heating with a fine temperature control could result in promising stabilization treatments.
Effect on orange juice of batch pasteurization in an improved pilot-scale microwave oven
ALBANESE, DONATELLA;CUCCURULLO, Gennaro;DI MATTEO, Marisa
2010
Abstract
The effects on orange juice batch pasteurization in an improved pilot-scalemicrowave (MW) oven was evaluated by monitoring pectin methyl-esterase (PME) activity, color, carotenoid compounds and vitamin C con- tent. Trials were performed on stirred orange juice heated at different temperatures (60, 70, 75, and 85 ◦ C) dur- ing batch process.MWpilot plant allowed real-time temperature control of samples using proportional integrative derivative (PID) techniques based on the infrared thermography temperature read-out. The inactivation of heat sensitive fraction of PME, that verifies orange juice pasteurization, showed a z-value of 22.1 ◦ C. Carotenoid content, responsible for sensorial and nutritional quality in fresh juices, decreased by about 13¯terMWpasteurization at 70 ◦ C for 1 min. Total of 7 carotenoid compounds were quantified during MW heating: zeaxanthin and β-carotene content decreased by about 26%, while no differences (P < 0.05) were found for β-cryptoxanthin in the same trial. A slight decrease in vitamin C content was monitored after MW heating. Results showed that MW heating with a fine temperature control could result in promising stabilization treatments.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
