Forced-Convection Steam Nuts Preheating
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Solution Overview
Problem
Conventional steam pasteurization of nuts at high temperatures causes moisture uptake and skin loosening, while methods to limit condensation either require additional equipment or batch handling, and result in longer processing times.
Innovation Solution
A steam cooker with a preheating chamber and a heating chamber that uses a forced-convection steam mixture at atmospheric pressure, maintaining temperatures between 85° C. and 99° C. to minimize water condensation and achieve pasteurization without skin loosening, while allowing for continuous processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional steam pasteurization is used at high temperatures, then pasteurization effectiveness is improved, but moisture uptake and skin loosening increase
Solution Approach 1:
The patent applies preliminary action by preheating the nuts in a separate preheating chamber before they enter the pasteurization chamber. This preheating step raises the nut temperature close to the steam temperature, preventing excessive condensation on the nut surface during pasteurization. The preheating chamber uses heating elements to gradually increase nut temperature, which eliminates the thermal shock that would otherwise cause skin loosening and moisture uptake while maintaining pasteurization effectiveness.
Solution Approach 2:
The patent changes the temperature parameter progression by using a two-stage process: first preheating at controlled rates, then pasteurizing at optimized temperatures. The system monitors and controls temperature parameters throughout the process, maintaining temperatures that achieve pasteurization (typically 72°C or higher for specific times) without excessive moisture uptake. This parameter control ensures skin integrity while achieving microbial deactivation.
2Object-affected harmful factors
If preheating is added to limit condensation, then skin damage is reduced, but device complexity increases
Solution Approach 1:
The patent merges the preheating and pasteurization functions into a single integrated pasteurizer device. The preheating chamber and pasteurization chamber are connected in sequence within one machine, allowing nuts to be preheated and then immediately pasteurized without manual intervention. This integration reduces the need for separate equipment while maintaining the benefits of controlled temperature progression and minimizing skin damage.
Solution Approach 2:
The pasteurizer is designed with multi-functionality, where the same device performs both preheating and pasteurization operations. The system can adjust operating parameters to handle different nut types and pasteurization requirements, making it a universal solution that eliminates skin damage without requiring multiple separate machines. The controller manages both heating stages with a single device.
3Object-affected harmful factors
If vacuum systems are used to limit water uptake, then condensation is reduced, but processing time increases due to batch handling
Solution Approach 1:
The patent implements continuous processing where nuts move continuously through the preheating chamber and then through the pasteurization chamber on a conveyor system. This eliminates the batch handling required by vacuum systems, maintaining high throughput while continuously limiting water uptake through controlled temperature management. The continuous flow allows for consistent temperature control and prevents the condensation issues that would otherwise require vacuum conditions.
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 reduces moisture uptake and processing time, enabling efficient pasteurization of nuts with minimal skin damage and increased throughput by controlling the steam atmosphere and using a combination of preheating and low-temperature heating.
Implementation Method 1
forcing a substantially homogeneous gaseous atmosphere comprising a steam mixture through the nuts in the heating chamber along a connection path intersecting the conveying path to heat the outer skins of the nuts
Implementation Method 2
The steam condenses on the outer surface of the nuts and raises their temperature
Implementation Method 3
conveying nuts along a conveying path through a preheating chamber
Data Source
AI summary
Method for pasteurizing almonds and other nuts with steam at atmospheric pressure. The amount of condensation on and the consequent water uptake of nuts is limited by pasteurizing the nuts in a heating chamber with a gaseous atmosphere including a steam mixture and forming a forced-convection path through the nuts. The limited water uptake maintains the quality of the nuts. A forced-convection steam cooker conveying food products on a foraminous conveyor belt forces the steam mixture through the nuts. A preheater preheats the nuts so that they can be pasteurized in the steam cooker at a temperature of between 85° C. and 99° C. to reduce the dwell time and increase throughput.