Antimicrobial Food Packaging Colloidal Metal Distribution
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Solution Overview
Problem
Existing food packaging technologies face challenges in extending the shelf life of meat and cheese products due to microbial growth, as antimicrobial substances used in packaging can leach into the products and have limitations at high processing temperatures, and the incorporation of solid metal oxides leads to sedimentation and agglomeration issues during processing.
Innovation Solution
The use of antimicrobial metal ions like Ag+, Cu+, Sn2+, and Zn2+ in a finely distributed colloidal form within the packaging layers, achieved through the reduction of metal salts in an organic solvent and subsequent extrusion, allows for a thin, evenly distributed metal layer that prevents microbial penetration without compromising strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If solid metal oxides are incorporated into the packaging layer, then antimicrobial effectiveness is achieved, but sedimentation and agglomeration occur during processing
Solution Approach 1:
The patent changes the physical-chemical state of metal particles from solid oxides to colloidal form with diameters between 1-100 nm. This parameter change in particle size and state prevents sedimentation and agglomeration during processing while maintaining antimicrobial effectiveness through the oligodynamic effect of metal ions.
Solution Approach 2:
The patent uses colloids as an intermediary carrier to distribute metal particles uniformly in the polymer matrix. The colloidal form acts as a mediator that prevents direct agglomeration of metal particles during processing, enabling stable incorporation into the packaging material.
2Strength
If the layer thickness is increased to ensure sufficient resilience, then packaging strength is improved, but the amount of antimicrobial metal increases
Solution Approach 1:
The patent changes the particle size parameter to nanometer scale (1-100 nm), which allows achieving sufficient antimicrobial effectiveness at very low concentrations (1-100 ppm). This enables thin layer design while maintaining both strength and antimicrobial function.
Solution Approach 2:
The patent uses the oligodynamic effect of metal ions, where trace amounts of metal particles (copies of the antimicrobial function) are sufficient to achieve the desired effect without requiring large quantities or thick layers.
3Reliability
If organic antimicrobial substances are added to the packaging, then antimicrobial effectiveness is achieved, but the substances degrade at high processing temperatures
Solution Approach 1:
The patent replaces unstable organic antimicrobial substances with inorganic metal particles that are thermally stable. The metal particles in colloidal form maintain their antimicrobial effectiveness through the oligodynamic effect without degrading at high processing temperatures.
4Manufacturing precision
If metal salts are reduced to metal particles in situ, then fine distribution is achieved, but processing complexity increases
Solution Approach 1:
The patent performs the reduction of metal salts to metal particles in advance during the masterbatch preparation stage, before the actual extrusion process. This preliminary action creates a stable colloidal suspension that can be easily incorporated into the polymer matrix without requiring complex in-situ reduction equipment.
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 effectively delays microbial proliferation and migration on the packaged food surface, maintaining packaging strength while avoiding the issues of sedimentation and agglomeration, with antimicrobial efficacy sustained through moisture absorption and diffusion.
Implementation Method 1
the metal is in the form of a colloid with an oligodynamic effect
Implementation Method 2
achieved through the reduction of metal salts in an organic solvent
Implementation Method 3
the metal is in the form of a colloid with an oligodynamic effect
Implementation Method 4
antimicrobial efficacy sustained through moisture absorption and diffusion
Implementation Method 5
antimicrobial efficacy sustained through moisture absorption and diffusion
Data Source
AI summary
The invention relates to a single or multi-layered food packaging based on plastic. The layer or at least one of the layers contains at least one antimicrobially active metal. At least one part of the antimicobially active metal has a finely distributed metallic form and the remaining part is in the form of a salt.