Food Sterilization Using Inductive Heating and Vacuum Cooling
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Solution Overview
Problem
Existing UHT systems for sterilizing aseptically packaged foods face challenges in treating foods with chunky portions, as the sterilization process alters structural properties and imposes significant shear stress, particularly during cooling, affecting the rheological properties of the product.
Innovation Solution
A method involving controlled heating of food to 110-130°C and cooling to 60-80°C, followed by immediate bottling and subsequent cooling to 30°C, using inductive heating, jacket cooling, or vacuum cooling, with the process optimized by controlling the F value and utilizing a combination of heating and cooling units to ensure efficient and rapid processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If continuous UHT sterilization with heat exchangers is used, then sterilization efficiency is improved, but the food's structural properties are altered and shear stress increases
Solution Approach 1:
The patent replaces the mechanical heat exchanger system with electromagnetic heating (induction or microwave). This substitution eliminates the mechanical shear stress caused by pumping and heat exchange while achieving rapid sterilization. The food is heated in situ within the container, avoiding the mechanical handling and pumping that cause structural degradation.
Solution Approach 2:
The patent extracts the heating function from the continuous flow system and applies it directly to the stationary food in the container. By taking out the need for continuous pumping and flow through heat exchangers, the food remains stationary during heating, preserving its structural integrity while still achieving sterilization.
2Loss of time
If rapid cooling is applied during sterilization, then processing time is reduced, but shear stress on the product increases
Solution Approach 1:
The patent uses electromagnetic heating which heats the food rapidly and uniformly without mechanical agitation. The heating is followed by controlled cooling where the food is drained and allowed to cool naturally or with gentle air circulation, avoiding the high shear stress that would occur with mechanical pumping through cooling exchangers.
Solution Approach 2:
The food drains under its own weight through a sieve into a cooling area, using gravity rather than mechanical pumping. This self-draining process minimizes shear stress while still achieving rapid cooling and processing.
3Reliability
If hot filling is used immediately after sterilization, then recontamination is prevented, but product quality may be compromised
Solution Approach 1:
The patent performs preliminary draining of the food through a sieve immediately after heating, removing excess moisture and heat before the filling operation. This preliminary action allows the food to be filled at a slightly lower temperature while still maintaining sterile conditions, thereby preserving quality while preventing recontamination.
Solution Approach 2:
The patent creates different temperature zones: the food is heated to sterilization temperature (110-130°C), then drained and allowed to cool slightly (80-95°C) before filling. This local quality variation ensures sterilization is achieved while the filling operation occurs at a temperature that preserves product quality.
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 method effectively sterilizes food while minimizing re-contamination and preserving product properties, allowing for rapid processing within less than an hour, ensuring efficient filling capacity and maintaining product quality by controlling temperatures and using parallel cooking and cooling units.
Implementation Method 1
The food can be heated inductively or with high frequency
Implementation Method 2
The food can be heated inductively or with high frequency
Implementation Method 3
Cooling is preferably achieved by jacket cooling and/or vacuum cooling
Implementation Method 4
Cooling is preferably achieved by jacket cooling and/or vacuum cooling
Data Source
AI summary
Heat sterilizing of food comprises heating the food in a container to 90-150[deg] C and cooling the container to 80[deg] C.