Shielded Data Logger for Microwave Food Sterilization
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Solution Overview
Problem
Current microwave-based food sterilization and pasteurization systems lack a reliable mechanism to ensure consistent processing across batches and identify areas requiring repair or adjustment, particularly in the U.S., where temperature monitoring is not as effectively implemented as in Europe.
Innovation Solution
A data logger is positioned within a food product package to sense temperature at the cold spot, recording temperature and time data to ensure accurate pasteurization or sterilization, and can be wirelessly transmitted, with configurations ensuring it does not interfere with microwave heating or alter the cold spot location.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a data logger is positioned within a food package to monitor temperature, then temperature monitoring accuracy is improved, but the data logger may interfere with microwave transmissions and alter the cold spot position
Solution Approach 1:
A dielectric member is introduced as an intermediary between the metallic data logger and the microwave field. This dielectric member shields the metallic data logger from direct microwave exposure while allowing the logger to accurately measure temperature at the cold spot, thus preventing interference with microwave transmissions while maintaining measurement accuracy
Solution Approach 2:
The patent uses a model food article with known dielectric properties to determine the optimal position and configuration of the data logger before actual processing. This allows the cold spot position to be accurately identified and the logger positioned accordingly without interfering with the actual food heating process
2Reliability
If temperature monitoring is implemented to ensure consistent pasteurization/sterilization across batches, then food safety and quality are improved, but the system complexity and cost increase
Solution Approach 1:
The data logger is designed as a self-contained device that autonomously records temperature data at the cold spot during microwave processing. The logger independently determines when the cold spot has reached the required temperature and for how long, eliminating the need for complex external monitoring systems and providing reliable verification of pasteurization/sterilization parameters
Solution Approach 2:
The patent changes the physical state or configuration of the data logger based on processing conditions. For example, the logger may be positioned in different locations within the package depending on the food type and microwave cavity configuration, or the dielectric shielding may be adjusted to optimize both measurement accuracy and minimal interference with the microwave field
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution provides reliable temperature and time profiles for ensuring proper pasteurization or sterilization, allowing for identification of processing line issues and ensuring consistent food quality across batches without altering the heating pattern or cold spot location.
Implementation Method 1
a member positioned for sensing the temperature at the cold spot of the package
Implementation Method 2
The data logger records temperature, and possibly other parameters of interest, against time
Implementation Method 3
Microwave sterilization of pre-packaged foodstuffs has been researched for a number of years
Data Source
AI summary
The time/temperature history of a food tray or pouch heated by microwave energy applied through a waveguide can be accurately assessed on positioning and stabilizing a shielded data logger in an orientation where the base of the data logger is located generally close to zero depth (near the side wall) and the tip projects to the cold spot in the tray or pouch. A frame can be used to assure stability of orientation in a pouch while bracing can be used to assure stability in a tray. The properly configured food tray or pouch can serve as an accurate witness device for food items being processed in a similar manner under microwave heating for, e.g., sterilization or pasteurization.