Continuous Yeast Fermentation with High Cell Density
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Solution Overview
Problem
Continuous fermentation processes for yeast fermented beverages face challenges in maintaining high yeast concentrations, which are crucial for efficient fermentation and reducing microbial infections, while also allowing for rapid product switching without intermediate cleaning or standstill.
Innovation Solution
A method involving consecutive continuous processing steps where wort is introduced into propagation vessels with recirculated yeast-containing residue under aerobic conditions, then transferred to fermentation vessels under anaerobic conditions, with optional recirculation and yeast separation, maintaining wet yeast content above 100 g/l to achieve high yeast concentrations and reduce fermentation times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If continuous fermentation is operated with high yeast concentrations to reduce microbial infections and improve efficiency, then reliability and productivity are improved, but device complexity and difficulty of maintaining stable yeast levels increase
Solution Approach 1:
The fermentation process is divided into multiple continuous stages (propagation vessels followed by fermentation vessels) with distinct functions. Each stage maintains optimized yeast concentrations independently, allowing high yeast levels in fermentation stages for microbial protection while managing overall process complexity through functional segmentation of the continuous system.
Solution Approach 2:
The process dynamically adjusts yeast concentration parameters across different stages and time periods. By controlling yeast levels to exceed 100 g/l in fermentation vessels while using separate propagation stages, the system optimizes reliability against microbial infections without requiring uniformly complex control throughout the entire process.
2Productivity
If continuous fermentation uses high yeast concentrations to reduce fermentation times and volumes, then productivity is improved, but energy consumption and operational complexity increase
Solution Approach 1:
The system maintains continuous fermentation operation with steady-state conditions, eliminating batch processing interruptions. High yeast concentrations (>100 g/l) are maintained continuously in fermentation vessels to sustain rapid fermentation rates without periodic restarts, improving productivity while spreading energy consumption evenly over time without major peaks.
Solution Approach 2:
The process transitions from traditional batch fermentation to continuous multi-stage fermentation, adding the dimension of temporal continuity and spatial staging. This dimensional change allows sustained high yeast concentrations and rapid fermentation rates while distributing energy requirements across continuous operation rather than periodic intensive processing.
3Productivity
If continuous fermentation process is designed for rapid product switching without cleaning, then productivity and adaptability are improved, but hygienic standards and product quality may be compromised
Solution Approach 1:
The system continuously separates and recycles yeast cells from fermented wort through centrifugation or filtration. Yeast is recovered and returned to propagation or fermentation vessels, while clarified wort proceeds to subsequent processing. This continuous separation and recovery mechanism enables rapid product switching without cleaning by maintaining hygienic conditions through active yeast management and separation.
Solution Approach 2:
The continuous fermentation and separation process operates without interruption or cleaning cycles. Yeast is continuously managed through propagation, fermentation, and separation stages, maintaining hygienic conditions throughout. This uninterrupted continuous operation enables instant product switching while preserving quality through consistent hygienic control rather than periodic cleaning.
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 method enables high-quality beer production with reduced fermentation times and volumes, increased resistance to microbial infections, and the ability to instantly switch between different products on the same equipment without cleaning, leveraging extremely high yeast concentrations.
Implementation Method 1
a method of producing yeast fermented beverages which method comprises the following consecutive continuous processing steps: a. introducing wort into a series of one or more propagation vessels in which it is combined with a recirculated stream of yeast-containing residue and in which the yeast is allowed to propagate under aerobic conditions... b. transferring the yeast-containing wort from the propagation vessel into a series of one or more fermentation vessels in which the yeast is kept suspended under anaerobic conditions and is allowed to metabolise carbohydrates present in the wort
Data Source
AI summary
The present invention relates to a method of producing yeast fermented beverages, which method comprises the following consecutive continuous processing steps: a. introducing wort into a series of one or more propagation vessels in which it is combined with a recirculated stream of yeast-containing residue and in which the yeast is allowed to propagate under aerobic conditions whilst being kept suspended; b. transferring the yeast-containing wort from the propagation vessel into a series of one or more fermentation vessels in which the yeast is kept suspended under anaerobic conditions and is allowed to metabolise carbohydrates present in the wort; c. transferring at least a part of the fermented wort from the series of one or more fermentation vessels to one or more separators to remove a yeast-containing residue; d. recirculat ing part of the yeast-containing residue to the series of one or more propagation vessels; and e. feeding the remainder of the fermented wort to subsequent processing steps; wherein the wet yeast content of the wort in the series of one or more fermentation vessels is maintained at more than 100 g/l. The utilisation of very high yeast concentrations offers the advantage that fermentation times and/or fermenter volume can be reduced substantially. Furthermore, continuous fermentations conducted at high yeast concentrations are less vulnerable to microbial infections.