Killer Yeast Toxin Control for Beer Fermentation Attenuation
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Solution Overview
Problem
Current methods for controlling Saccharomyces cerevisiae var. diastaticus infections in beer fermentation, such as pasteurization, negatively affect beer quality, particularly in aggressively hopped styles, and there is a need for alternative methods to stabilize beer without destroying hop aromas.
Innovation Solution
The use of killer yeast toxins, such as K1, K2, or K28, is introduced during fermentation to deactivate diastatic yeasts, either directly or through genetically modified host cells, to control over-attenuation and prevent further fermentation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pasteurization is used to control diastatic yeast infections, then beer stability is improved, but hop aroma quality deteriorates
Solution Approach 1:
A killer toxin-producing yeast strain is introduced as an intermediary organism that selectively targets and eliminates diastatic yeasts through toxin production, rather than using pasteurization. This mediator approach allows specific pathogen elimination while preserving the beer's sensory qualities including hop aromas.
Solution Approach 2:
The invention changes the control parameter from thermal treatment (pasteurization temperature) to biological treatment (killer toxin concentration and producing organism). This parameter shift enables selective yeast control without the thermal degradation that harms hop compounds.
2Manufacturing precision
If killer toxin is added to deactivate diastatic yeast, then over-attenuation is controlled, but additional process steps are required
Solution Approach 1:
The killer toxin-producing yeast strain performs self-service by autonomously producing and secreting the killer toxin into the fermentation environment. This eliminates the need for external toxin addition and simplifies the process, as the controlling organism is already present in the fermentation system.
Solution Approach 2:
The killer toxin-producing yeast strain serves multiple functions: it acts as both the primary fermenting organism and the biocontrol agent against diastatic yeasts. This multi-functionality reduces process complexity by combining fermentation and pathogen control into a single organism's role.
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 killer yeast toxins effectively stabilize beer by preventing over-attenuation, preserving beer quality and hop aromas, as demonstrated by maintaining specific gravity levels and reducing gushing and off-flavors.
Implementation Method 1
The killer toxin is added in an amount effective to deactivate the fungus
Data Source
AI summary
A method of controlling attenuation in a fermentation process includes culturing a fungus in a medium to produce a fermented liquid and adding a killer toxin to the fermented liquid. The killer toxin is added in an amount effective to deactivate the fungus.