Mushroom Substrate Pasteurization Using Controlled Hot Air Circulation

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Solution Overview

Problem

Current mushroom cultivation at an industrial scale faces inefficiencies in substrate pasteurization due to high energy consumption and environmental impact from using fossil fuels for steam sterilization, which requires long processing times and results in low energy efficiency and potential microbial contamination.

Innovation Solution

A method and device utilizing controlled air circulation with heat from alternative sources, such as combined heat and power plants or hot water boilers, to pasteurize mushroom substrates within a controlled humidity environment, reducing processing time to less than 8 hours and eliminating condensate issues, while maintaining substrate sterility.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If high temperature saturated steam is used for substrate pasteurization, then sterilization effectiveness is improved, but energy consumption increases and processing time extends

Engineering Contradiction:
Improvesterilization effectivenessVSAvoidenergy consumption
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The invention changes the fundamental parameter of the heating medium from saturated steam to hot air. This parameter change allows pasteurization to be achieved with lower energy consumption while maintaining effectiveness, as hot air can be heated to the required temperatures without the energy losses associated with steam generation and condensation. The hot air system eliminates the need for continuous steam supply and condensate removal, significantly reducing energy usage.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention extracts and eliminates the steam generation and condensate removal processes from the pasteurization system. By using hot air as the heating medium, the system removes the harmful condensate formation that occurs with steam, thereby eliminating the energy waste associated with heating, condensing, and disposing of large amounts of water. This extraction of the steam-based process resolves the energy consumption contradiction.

Inventive Principle:
Principle #2Taking out (Extraction)

2Reliability

If substrate is bathed in steam for extended periods, then microbial contamination is prevented, but processing time increases

Engineering Contradiction:
Improvesubstrate sterilityVSAvoidprocessing time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The invention changes the heating medium parameter from steam to hot air, which allows for more uniform and efficient heat transfer to the substrate. Hot air can penetrate and circulate more effectively around the substrate material, achieving the required pasteurization temperature throughout the substrate more quickly. This parameter change reduces processing time while maintaining the sterility requirement.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention substitutes the steam-based thermal system with a hot air-based thermal system. This substitution eliminates the phase change mechanism (steam condensation) that causes prolonged processing times and instead uses direct hot air convection and conduction for heating. The result is faster pasteurization that achieves the same microbial elimination effectiveness in reduced time.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Productivity

If pressurized steam autoclave is used, then sterilization speed is improved, but equipment corrosion increases and maintenance costs rise

Engineering Contradiction:
Improvesterilization speedVSAvoidequipment durability
Core Design Contradiction:
ProductivityVSEase of manufacture

Solution Approach 1:

The invention extracts and eliminates the pressurized steam autoclave system entirely, replacing it with a hot air pasteurization system operating at atmospheric pressure. This removal of the pressurized steam mechanism eliminates the source of equipment corrosion (condensate water and high pressure), thereby extending equipment life and reducing maintenance requirements while maintaining sterilization effectiveness.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The invention adopts a simpler, less expensive hot air heating system instead of expensive pressurized autoclave equipment. The hot air system uses standard heating elements and circulation fans that are less costly and more durable than autoclave systems. This substitution with simpler, more robust equipment reduces both initial investment and long-term maintenance costs while achieving the required sterilization speed.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

4Reliability

If steam pasteurization is applied, then microbial contamination is prevented, but condensate formation isolates substrate from heating

Engineering Contradiction:
Improvesubstrate sterilityVSAvoidheating efficiency
Core Design Contradiction:
ReliabilityVSLoss of energy

Solution Approach 1:

The invention extracts and eliminates the condensate formation process by replacing steam with hot air as the heating medium. Without phase change, there is no condensate to form films on substrate surfaces or equipment. This extraction resolves the heating efficiency problem by ensuring direct thermal contact between the heating medium and substrate without insulating water layers.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The invention substitutes the steam condensation mechanism with direct hot air heating. Instead of relying on steam condensation for heat transfer, the system uses hot air convection and conduction, which do not produce condensate. This substitution eliminates the energy loss associated with heating condensate and removes the insulating effect of water films, thereby improving heating efficiency while maintaining sterility.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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 approach significantly reduces pasteurization time and energy consumption, enhances efficiency, and prevents microbial contamination, allowing for reliable and sustainable industrial-scale mushroom cultivation with improved yields and reduced environmental impact.

Implementation Method 1

introducing air with a temperature of 65-90 °C into said chamber and subjecting said substrate to said air

Methodology Applied
Scientific EffectConvection: Convection

Implementation Method 2

said air is circulated through the chamber

Methodology Applied
Scientific EffectForced Convection: Forced Convection

Implementation Method 3

the humidity in said chamber is controlled such that condensate does not form on surface of the container

Methodology Applied
Scientific EffectHumidity control:

Data Source

PatentEP3547824B1Method and device for pasteurization of a substrate useable for growing mushrooms
Publication Date: 2023.12.20 BIOSTEAM AB
  • EP3547824B1 patent drawingFigure 1~2
  • EP3547824B1 patent drawingFigure 3~4

AI summary

The invention relates to a device configured for growing of mushrooms, said device comprising: a chamber (2), configured to house mushroom growing substrate (5A) provided in enclosures, an air blower device (8) configured to circulate air through said chamber (2), an air heater device (11) configured to heat air that is to be circulated through said chamber (2) to a temperature of 90 °C or below, and an air humidity control device (12, 13) configured to control the humidity of the air circulated through the chamber (2) within a predetermined range.