<p>The overall hypothesis is that computer aided design of radiofrequency (RF) applicators and treatment systems for continuous processing of low-moisture food with appropriate mixing will result in improved heating uniformity. Improved heating uniformity will facilitate development of high temperature short time RF treatments for enhanced microbiological safety of the products. </p><p>Specific objectives of this proposal are to: Develop a continuous RF processing system for in-package powder and pumpable food pastes. Measure temperature-dependent dielectric and thermal properties of selected low moisture food products Using computer simulation, design applicator and package configuration for uniform heating of low moisture foods Determine RF process parameters based on microbial inactivation kinetics and product quality deterioration kinetics Validate process design with microbial challenge study with the selected low-moisture food products.</p>
<p>NON-TECHNICAL SUMMARY:<br/> Recent illness associated with ingestion of multiple low-moisture foods have heightened concern of their microbial safety. There is a critical need to minimize the risk of foodborne pathogens in low-moisture foods by incorporating a lethality step in the last leg of production processes. Radio frequency (RF) waves heat these products rapidly and volumetrically and therefore we propose to develop a high temperature short time RF process. Heating non-uniformity and arcing have been the major issues limiting the successful deployment of RF process technology. We propose modeling as a tool to develop guidelines for design of RF applicators and design of continuous treatment systems (pumps for paste and conveying and packaging systems for powders) to improve heating uniformity and therefore food safety. The overall hypothesis is that computer aided
design of RF process system will result in improved heating uniformity which will facilitate development of high temperature short time RF treatments for enhanced microbiological safety of the products. The specific objective are to: 1) develop continuous RF processing system for in-package powder (wheat flour) and pumpable food pastes (peanut butter) by using computer simulation as tool for designing applicator and package configuration for uniform heating, 2) determine RF process parameters based on microbial inactivation kinetics and product quality deterioration kinetics, and 3) validate process design with microbial challenge study. The successful development of RF processing for two products will wide open the application of this technology in to other low moisture food products. Development of this RF-based lethality step will improve microbiological safety and will give a
competitive edge to US food processers in global market.
<p>APPROACH:<br/> Thermal destruction kinetics data (D and z values) of pathogens in low-moisture foods (wheat flour and peanut butter) will be obtained from the Dr. Marks group (Refer to his collaborative support letter). Time-temperature combinations required for desired inactivation of pathogen in each food item will be identified based on log reduction required and D and z values of the Salmonella spp. As RF heating is rapid, we will be striving for high temperature short time treatment. However, quality and stability of the low-moisture food products after high temperature short time RF treatment can be an issue. Quality evaluation study will be performed to insure that the selected treatment do not imparts considerable undesirable changes to the quality of treated product. We have already developed a preliminary heat transfer model to understand the interaction of RF
waves with food products. Using our computer model, electrodes and food package shape will be modified to improve the heating uniformity. The package and electrode configuration will be modified and fabricated. Validation of the design change will be performed by conducting experiments in the modified RF systems and measuring the temperatures using fiberoptic thermocouples and IR imaging system. The heat transfer model will be integrated with the microbial destruction model to determine the inactivation of pathogens during processing. Finally microbial challenge studies on pilot scale RF unit will be performed to validate the efficacy of the designed process for the selected products.