Process for shelf-life extension of fish
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Solution Overview
Problem
Current methods for preserving and packaging fish do not effectively extend its shelf life beyond a few days while maintaining freshness, especially for shipping and retail presentation.
Innovation Solution
A process involving initial chilling, filleting, portioning, vacuum skin packaging, super-chilling using a spiral chilling chamber with cooled air, and controlled temperature storage to maintain fish core temperature between -4°C to -2°C, allowing for up to 12 days of shelf life without additional insulation or handling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If conventional chilling and vacuum packing is used, then fish can be preserved for several days, but shelf life is limited and cannot be extended beyond a few days while maintaining freshness
Solution Approach 1:
The patent applies parameter changes by transitioning from conventional chilling temperatures to super-chilling temperatures (below -4°C but above freezing point), and by controlling oxygen levels in the packaging atmosphere. This changes the physical state and chemical reactions occurring in the fish, thereby extending shelf life while maintaining freshness.
Solution Approach 2:
The patent utilizes phase transitions by super-chilling the fish to a temperature range where water in the fish tissue approaches freezing but remains in liquid state, creating a metastable state that slows bacterial growth and enzymatic activity without forming ice crystals that would damage tissue structure.
2Duration of action of moving object
If extended shelf life is achieved through conventional methods, then storage time increases, but additional insulation and special handling are required for shipping
Solution Approach 1:
The patent applies preliminary action by super-chilling the fish to -4°C or below before packaging, and by establishing the desired oxygen level in the packaging atmosphere in advance. This preliminary treatment allows the fish to maintain extended shelf life during shipping without requiring additional insulation or active chilling equipment in the packaging.
3Duration of action of moving object
If vacuum packing is used to extend shelf life, then storage duration increases, but bacterial control and freshness maintenance become challenging
Solution Approach 1:
The patent applies inert atmosphere by controlling the oxygen level in the packaging environment, creating a modified atmosphere that is less conducive to bacterial growth and oxidation. This inert or low-oxygen environment helps preserve freshness and control bacterial proliferation during extended storage.
Solution Approach 2:
The patent changes the temperature parameter to super-chilling levels (below -4°C) which significantly reduces bacterial metabolic activity and growth rates, while maintaining the fish in a non-frozen state that preserves texture and quality.
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
The process extends the shelf life of fish to 12 days, maintaining freshness and reducing bacterial count, while providing a consumer-friendly, ready-to-sell product that can be shipped without special containers or additional chilling procedures.
Implementation Method 1
a spiral chilling chamber, having a closed environment within which air is circulated vertically through a spiral-mesh open conveyor holding the packages and is cooled by a heat exchanger which draws air in and delivers it between heat exchanger or evaporator plates
Implementation Method 2
cooled by a heat exchanger which draws air in and delivers it between heat exchanger or evaporator plates
Implementation Method 3
The super-chilling of step (f) is implemented by delivering air in the range of -25°C to -30°C to the fish for a cycle time of approximately 60 minutes
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
A process for treating and packaging fish comprising the steps of receiving (1) and inspecting fish at a point of intake; chilling (2) the fish; and fileting and portioning (4) the fish. The process includes holding (6) the fileted and portioned fish in bulk production trays in an environment of - 1°C to +1°C; followed by packing (7) the portions to provide a package which is vacuum skin sealed (8, 101), wherein the fish is vacuum skin packed by placing the portions in a retail individual-product tray and covered with a skin film, and sealing with a vacuum pressure of less than 5mBar. The packages are super-chilled in a super-chill stage (9, 200), to a temperature in the range of -4°C to -2°C during a time duration in the range of 45mins to 180mins. The superchilling is implemented by delivering air with a temperature in the range of -25°C to -30°C to the packages. The method finally includes storing (10) the packages in a chill hold environment at a temperature of -6°C to -1°C; and despatching the packaged fish portions for transport to retailers. The packages have a shelf life up to 12 days (Fig. 5) arising from the combination of steps in the process.