February 17/Campobasso, Italy/Electronics Business Journal -- "The effects on orange juice batch pasteurization in an improved pilot-scale microwave (MW) oven was evaluated by monitoring pectin methyl-esterase (PME) activity, color, carotenoid compunds and vitamin C content Trials were performed on stirred orange juice heated at different temperatures (60, 70, 75 and 85 degrees C) during batch process. MW pilot plant allowed real-time temperature control of samples using proportional integrative derivative (PID) techniques based on the infrared thermography temperature read-out," scientists in Campobasso, Italy, report.

"The inactivation of heat sensitive fraction of PME, that verifies orange juice pasteurization, showed a z-value of 22.1 degrees C. Carotenoid content, responsible for sensorial and nutritional quality in fresh juices, decreased by about 13% after MW pasteurization at 70 degrees C for one minute. Total of seven carotenoid compounds were quantified during MW heating: zeazanthin and beta-carotene content decreased by about 26%, while no differences (P<0.05) were found for beta-cryptoxanthin in the same trial. A slight decrease in vitamin C content was monitored after MW heating," wrote L. Cinquanta and colleagues, University of Molise.