Dielectric Properties and Heating Rate of Broccoli Powder as Related to Radio Frequency Heating

摘要

Many low moisture foods, including dried vegetables and spices, have been used for various applications such as coating materials, seasoning mixes and flavorings. Recently, an outbreak of Salmonella Wandsworth and Typhimurium has been associated with broccoli powder used for coating of snacks [3]. The safety issues of low moisture foods became a major concern in the food industry and forced it to seek an appropriate pasteurization process. Radio Frequency (RF) heating is a volumetric heating method with adjustable heating rate, appropriate energy efficiency, and short heating time. It has been applied in the food industry for applications such as disinfestation, enzyme inactivation, pasteurization and sterilization [1,2]. Because of its high potential, RF heating can be applied as an alternative pasteurization method for low moisture foods. The objectives of this study were (1) to measure the dielectric properties of the broccoli powder at frequencies from 1 to 30 MHz, different moisture contents (6.9-14.9% w.b.), and temperature from 20 to 80°C, (2) to evaluate the RF heating rate in broccoli powder as influenced by moisture content and compaction density at 27.12 MHz.