Microwave pasteurization of pre-packaged carrots

This research investigated the application of 915 MHz microwaves in pasteurizing pre-packaged vegetables. A specially designed 915 MHz single-mode microwave-assisted pasteurization (MAP) system was used to process carrot cuboids in brine pre-packaged in 8-oz polymer pouches. Gellan gel was formulated and selected as the model food to simulate the real foods processed by the MAP system; heating patterns and cold spots of the pouched samples were detected by a chemical-marker based computer vision method. Two MAP processes (F90°C = 3 min and F90°C = 10 min) targeting Clostridium botulinum type E spores were developed and compared with conventional hot water (HW) processes resulting in equivalent microbial safety. Compared with an equivalent HW process, MAP process greatly reduced the total processing time, reduced the cook values and improved quality uniformity of the products. Quality evaluation showed the impacts of MAP processing on each quality attribute of carrot products depended on the specific quality parameter selected.