Frozen Salad Sauce Coating for Listeria Inhibition
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Solution Overview
Problem
Ready-to-eat food products, such as main course salads, face challenges in extending shelf life due to microbial growth, particularly Listeria monocytogenes, which can thrive at refrigerator temperatures, limiting their usability and posing health risks.
Innovation Solution
A method involving cryogenic freezing and coating of food components with a sauce having a pH between 2.5 and 5, a salt content between 5 and 15%, and an oil content between 25 and 50%, followed by packaging, which results in a product with a pH between 4 and 6 and a water activity between 0.978 and 0.990, effectively inhibiting microbial growth and extending shelf life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If traditional packaging methods with preservatives or gassing are used, then shelf life is extended, but the method is not universally applicable to different food products and may require multiple solutions
Solution Approach 1:
The patent applies parameter changes by controlling the pH of the sauce coating between 2.5 and 5.0, which creates an acidic environment that inhibits Listeria growth. This chemical parameter modification provides a universal solution applicable to various food products without requiring different preservation methods for each product type.
Solution Approach 2:
The patent uses a composite coating consisting of sauce with specific pH, salt content (5-15%), and oil content (25-50%). This multi-component coating system provides both preservation functionality and versatility across different food products, eliminating the need for multiple separate solutions.
2Duration of action of stationary object
If the sauce has a low pH (2.5-5) to inhibit microbial growth, then shelf life is extended, but the taste and quality of the food product may be affected
Solution Approach 1:
The patent optimizes the pH parameter within a specific range (2.5-5.0) that is sufficiently acidic to inhibit Listeria growth but not so acidic as to significantly impact food quality and taste. This balanced parameter selection resolves the contradiction between preservation effectiveness and sensory quality.
Solution Approach 2:
The composite sauce coating includes not only acidic components for pH control but also salt (5-15%) and oil (25-50%), which contribute to flavor enhancement and quality maintenance. This composite formulation ensures that the preservation function does not compromise the sensory properties of the food.
3Duration of action of stationary object
If cryogenic freezing and sauce coating are applied, then Listeria growth is inhibited and shelf life is extended, but the process complexity increases
Solution Approach 1:
The patent applies preliminary action by freezing the food components before coating them with the sauce. This sequence simplifies the overall process because the frozen surface provides better adhesion for the sauce coating and the low temperature during coating helps maintain the acidic environment's effectiveness without requiring additional heating or treatment steps later.
Solution Approach 2:
The patent utilizes phase transitions by freezing the food components and then applying the sauce coating which may partially freeze or adhere to the cold surface. This phase transition approach simplifies the process by using temperature differential to achieve both preservation and coating adhesion in a single integrated step rather than requiring separate complex processes.
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 method ensures a shelf life of up to 18 months at -18°C and at least 48 hours after thawing at refrigerator temperatures, reducing the risk of Listeria monocytogenes growth and allowing safe consumption without heating.
Implementation Method 1
cooling one or more types of frozen meal components to a temperature between -30°C and -40°C in a cryogenic mixer
Implementation Method 2
individually coating at least 90% of the cryogenically frozen meal components from step b) with a sauce in a cryogenic mixer, wherein the sauce has a pH between 2.5 and 5
Data Source
Figure 1
AI summary
The present invention concerns the production of a frozen food product, more specifically a main course salad. The method described herein contributes to the shelf life of the food product and its food safety by preventing the growth of food pathogens.