Extended Shelf Life Milk Production Process
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Solution Overview
Problem
Current methods for producing long-life milk do not adequately balance the inactivation of bacteria and enzymes to achieve storage stability while maintaining good taste and visual properties for extended periods, particularly at room temperature.
Innovation Solution
A process involving two sequential heat treatment steps: the first at 94-96 °C for 2-4 minutes and the second at 125-135 °C for 50-400 seconds, both by indirect heating, to inactivate spores and enzymes effectively, ensuring long-life milk stability for up to 12 months at room temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional UHT processing is used (heating above 140°C for 3 seconds), then bacterial spores are inactivated achieving commercial sterility, but the milk develops cooked taste and reduced quality
Solution Approach 1:
The patent applies parameter changes by modifying the thermal processing parameters from traditional UHT (above 140°C for 3 seconds) to a new regime (94-96°C for 2-4 minutes followed by 125-135°C for 50-400 seconds). This changes the temperature-time profile to achieve spore inactivation while minimizing cooked taste development, directly resolving the contradiction between reliability of sterilization and quality preservation
Solution Approach 2:
The patent segments the single UHT heating step into two distinct sequential heating steps: a first step at 94-96°C for 2-4 minutes to inactivate enzymes and vegetative cells, and a second step at 125-135°C for 50-400 seconds to inactivate spores. This segmentation allows each step to target specific microbial populations without exposing the milk to excessive temperatures that cause cooked taste, thereby resolving the contradiction
2Reliability
If extended heating is used to inactivate enzymes like plasmin, then enzymatic spoilage is prevented, but thiamine loss increases and quality deteriorates
Solution Approach 1:
The patent applies parameter changes by optimizing the temperature and time parameters of the first heating step to 94-96°C for 2-4 minutes. This specific parameter range is sufficient to inactivate enzymes like plasmin (achieving at least 3 log inactivation) while limiting thiamine loss to less than 15%, thereby resolving the contradiction between reliable enzyme inactivation and nutrient preservation
3Productivity
If single-step UHT processing is used, then the process is simple and fast, but the shelf life at room temperature is limited and quality deteriorates during storage
Solution Approach 1:
The patent segments the processing into two sequential heating steps with specific time and temperature parameters. The first step (94-96°C for 2-4 minutes) inactivates enzymes and vegetative cells, while the second step (125-135°C for 50-400 seconds) inactivates spores. This segmentation achieves comprehensive microbial inactivation for long shelf life at room temperature (6-12 months) while maintaining processing efficiency, resolving the contradiction between processing simplicity and shelf life stability
Solution Approach 2:
The first heating step at 94-96°C serves as a preliminary action that inactivates enzymes and vegetative cells before the second spore-inactivation step. This preliminary action reduces the burden on the second step and prevents enzymatic spoilage during storage, thereby achieving long shelf life stability without significantly increasing overall processing complexity
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 achieves significant inactivation of bacterial spores and enzymes, maintaining milk quality and preventing enzymatic spoilage, resulting in a product with excellent storage stability and taste retention for several months, superior to traditional UHT milk.
Implementation Method 1
Heating the raw milk to be treated for a period of about 2 to about 4 minutes to a temperature in the range of 94 to 96 °C
Implementation Method 2
Heating the treated milk from step (b) for a period of about 50 to about 400 seconds to a temperature in the range of about 125 to 135 °C
Data Source
AI summary
A long-life milk with a shelf life of at least 5 months at room temperature is proposed, obtained by (a) subjecting the raw milk to be treated to a first heating to a temperature in the range of approximately 85 to 100 °C for a period of approximately 1 to 20 minutes and (b) subjecting the treated milk to a second heating to a temperature in the range of approximately 125 to 135 °C for a period of approximately 50 to 400 seconds. A manufacturing process is also claimed.