Microwave Sterilization of Food Containers via Periodic Inversion

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Solution Overview

Problem

Conventional methods for sterilizing food and beverage products in containers, such as hot-fill and tunnel sterilization, face issues like energy inefficiency, long processing times, and potential damage to containers, while also not ensuring complete sterilization due to agglomeration of inclusions and uneven heating.

Innovation Solution

A method using non-ionizing electromagnetic radiation, specifically microwave and radiofrequency energy, to heat the products within containers, combined with a manipulation sequence that involves repeated inversions to ensure thorough heating and distribution of heat throughout the product and container, achieving commercial sterilization temperatures in a shorter time without damaging the containers or degrading the product's quality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional hot-fill sterilization is used, then sterilization of container interiors is achieved, but solid inclusions agglomerate in container necks and caps, preventing complete sterilization

Engineering Contradiction:

Improvesterilization completenessVSAvoidinclusion distribution uniformity

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The container undergoes periodic inversion movements during the sterilization process, alternating between upright and inverted positions. This periodic motion prevents solid inclusions from settling and agglomerating in the neck and cap regions, ensuring uniform distribution and complete sterilization of all container surfaces including closures.

Inventive Principle:

Principle #19Periodic action

2Reliability

If conventional tunnel sterilization is used, then sterilization is achieved, but processing time is long (10-20 minutes or more)

Engineering Contradiction:

Improvesterilization effectivenessVSAvoidprocessing time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent replaces the conventional thermal conduction-based sterilization system with a microwave electromagnetic radiation system. Microwaves directly heat the product and container contents through dielectric heating, achieving sterilization temperatures much faster than conventional hot water spraying or steam heating, thereby reducing processing time from 10-20 minutes to a significantly shorter duration.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If conventional tunnel sterilization is used, then sterilization is achieved, but energy efficiency is low (30-50% heat delivery)

Engineering Contradiction:

Improvesterilization effectivenessVSAvoidenergy efficiency

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent substitutes the inefficient thermal conduction and convection system with microwave electromagnetic radiation. Microwaves directly couple energy to the product and container through dielectric heating, eliminating the need for heat exchangers, steam generation, and hot water circulation systems. This direct energy transfer achieves superior energy efficiency compared to the 30-50% heat delivery of conventional tunnel sterilization.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Reliability

If prolonged high temperature sterilization is used, then sterilization is achieved, but thermal abuse degrades product quality and container integrity

Engineering Contradiction:

Improvesterilization effectivenessVSAvoidthermal degradation

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent replaces prolonged thermal conduction heating with rapid microwave dielectric heating. Microwaves heat the product and container simultaneously and uniformly from the inside out, achieving sterilization temperatures in a fraction of the time required by conventional methods. This rapid heating prevents thermal abuse that would otherwise degrade product organoleptic properties and compromise container structural integrity.

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 processing time, enhances energy efficiency, prevents agglomeration of inclusions, and ensures complete sterilization of both the product and container surfaces, allowing for longer shelf life without the need for chemical preservatives, while being cost-effective and environmentally friendly.

Implementation Method 1

transmitting non-ionizing electromagnetic radiation, specifically microwave and radiofrequency energy, to heat the products within containers

Methodology Applied

Scientific EffectMicrowave radiation: Microwave Radiation

Implementation Method 2

heating the products within containers, combined with a manipulation sequence that involves repeated inversions to ensure thorough heating

Methodology Applied

Scientific EffectDielectric heating: Dielectric Heating

Data Source

PatentEP2779847B1In-package non-ionizing electromagnetic radiation sterilization

Publication Date: 2018.08.01 PEPSICO INC

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AI summary

A method for reducing microorganisms (sterilization) in a free-flowing product in a container. The product in the container is radiated with non-ionizing electromagnetic radiation at an energy density sufficient to achieve commercially sterile temperature and is manipulated in a manner to distribute heat and ensure that the product and the container reach a temperature sufficient to commercially sterilize the product and the interior surfaces of the container.