Powder Sterilization via Rapid Pressure Reduction
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Solution Overview
Problem
Conventional thermal sterilization methods for powders or grains are inefficient in killing microorganisms on the surface while minimizing heat exposure to the material, leading to quality degradation, and require longer heating times to effectively kill heat-resistant bacteria, which further degrades the material.
Innovation Solution
A method involving brief exposure to heated condensable gas followed by rapid pressure reduction, where the surface microorganisms are heated for a short duration, and then instantly released into a lower-pressure environment, minimizing the heat history of the powder or grain and effectively killing microorganisms without significant material degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thermal sterilization is performed by indirect or direct heating with steam or superheated steam, then microorganisms are killed effectively, but the heating time must be extended to several seconds which causes quality degradation of the powder or grain
Solution Approach 1:
The invention utilizes the phase transition of water inside microorganisms from liquid to vapor through rapid pressure reduction. When pressurized powder or grain is suddenly depressurized, intracellular water boils and expands, mechanically destroying microorganisms and insect pests without requiring prolonged thermal exposure that would degrade the material quality.
Solution Approach 2:
The invention applies preliminary heating at moderate temperatures (80-200°C) for a short duration (0.1-2 seconds) to raise the temperature of microorganisms to near-boiling point, then immediately applies pressure reduction to trigger intracellular water vaporization. This two-stage approach prepares the system for effective sterilization while minimizing thermal damage to the material.
2Reliability
If heating temperature and time are increased to kill heat-resistant bacteria, then sterilization reliability improves, but quality degradation of the material increases
Solution Approach 1:
The invention replaces prolonged thermal sterilization with rapid pressure-induced phase transition. By suddenly reducing pressure from pressurized conditions (0.1-1.0 MPa) to atmospheric pressure, intracellular water undergoes flash vaporization, mechanically disrupting heat-resistant bacteria and spores without requiring extended heating that would degrade material quality.
Solution Approach 2:
The invention substitutes thermal sterilization with a mechanical sterilization mechanism. Instead of relying on thermal energy to denature proteins over time, the system uses rapid pressure reduction to generate mechanical stress through intracellular water vaporization, physically destroying microorganisms while preserving material quality.
3Reliability
If conventional thermal sterilization methods are used, then microorganisms are killed, but the apparatus requires long heated gas flow pipes increasing size and complexity
Solution Approach 1:
The invention eliminates the need for long heated flow pipes by using rapid pressure reduction instead of prolonged heating. The phase transition of intracellular water upon depressurization occurs instantaneously, allowing sterilization in a compact apparatus without requiring extended residence time in heated zones.
Solution Approach 2:
The invention rushes through the sterilization process by combining brief heating (0.1-2 seconds) with immediate pressure reduction. This rapid two-stage process achieves effective sterilization without requiring the powder or grain to traverse long heated pathways, thereby reducing apparatus size and complexity.
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 achieves rapid and effective sterilization with minimal quality degradation, capable of killing insect pests and their eggs, and reduces the size and complexity of the sterilization apparatus by shortening the heated gas flow pipe length.
Implementation Method 1
the surface microorganisms are heated for a short duration
Implementation Method 2
heated condensable gas
Implementation Method 3
rapid pressure reduction
Data Source
Figure 1
Figure 2
AI summary
[Problem to be solved] To provide a method for sterilizing powder or grain by which the heating time is a minimum required time to reduce thermal degradation of the quality of the powder or grain while securing sufficient sterilization effect, and a sterilizing apparatus employing the method. [Means to solve the problem] The problem is solved by a method for sterilizing powder or grain, and a sterilizing apparatus employing the method, and the method includes applying heat and pressure in which powder or grain is supplied into a heated gas flow pipe kept under heated and pressurized conditions, and the powder or grain is transferred while coming into direct contact with a heated condensable gas in the heated gas flow pipe for 0.008 to 2 seconds, and instantaneous reduced pressure sterilizing in which the heated condensable gas and the powder or grain are instantaneously released into a space having a pressure lower than that in the heated gas flow pipe, water contained in microorganisms adhering to the powder or grain is boiled rapidly, and tissues of the microorganisms are destroyed.