Light-Stable Hop Extract via Pre-Isomerization and Reduction
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Solution Overview
Problem
Conventional brewing methods result in inefficient alpha acid extraction and isomerization, leading to low yields of iso-alpha acids, which are prone to light-induced degradation, causing 'lightstruck' flavor in beer.
Innovation Solution
Illuminating pre-isomerized hop extracts with sunlight to enhance light stability without significantly affecting bitterness or flavor, resulting in the formation of specific hop-derived substances that prevent the formation of 3-MBT.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional brewing methods are used for alpha acid extraction and isomerisation, then the process is simple and traditional, but the iso-alpha acid yield is low (below 40%) and the products are prone to light-induced degradation
Solution Approach 1:
The patent applies preliminary action by performing isomerisation of alpha acids to iso-alpha acids before the brewing process (off-line pre-isomerisation). This allows the iso-alpha acids to be formed in advance and then protected from light degradation through subsequent reduction to hydroxy-acids, which are light-stable. The pre-formed iso-alpha acids are then added to beer during packaging, avoiding exposure to light during storage and distribution.
Solution Approach 2:
The patent changes the chemical parameter of the iso-alpha acids by reducing them to hydroxy-acids (e.g., isohumulone to 3-methyl-2-butene-1-thiol resistant compounds). This chemical transformation eliminates the light-sensitive carbonyl group, converting the light-unstable iso-alpha acids into light-stable derivatives that maintain bitterness without undergoing photo-degradation.
2Productivity
If alpha acids are isomerised outside the brewing process (off-line pre-isomerisation), then iso-alpha acid yield is improved, but the products become susceptible to lightstruck flavor formation
Solution Approach 1:
The patent converts the harmful light-sensitive property of iso-alpha acids into a benefit by using the knowledge of their instability to drive their transformation into stable derivatives. The light sensitivity that causes degradation is exploited as a motivation to perform reduction chemistry, converting the vulnerable carbonyl group into a light-stable hydroxyl group, thereby eliminating the harmful photo-reaction pathway while preserving the desired bittering function.
Solution Approach 2:
The patent changes the chemical parameter of the iso-alpha acids by reducing them to hydroxy-acids (e.g., isohumulone to 3-methyl-2-butene-1-thiol resistant compounds). This chemical transformation eliminates the light-sensitive carbonyl group, converting the light-unstable iso-alpha acids into light-stable derivatives that maintain bitterness without undergoing photo-degradation.
3Reliability
If hop extracts are reduced to form light-stable products, then light stability is improved, but the bitterness and flavor characteristics may be affected
Solution Approach 1:
The patent carefully controls the reduction parameter to selectively transform only the light-sensitive carbonyl group while preserving the bittering-active structural features. By using mild reducing agents and controlled reaction conditions, the patent modifies the chemical structure just enough to eliminate photo-degradation pathways while maintaining the molecular features responsible for bitterness and flavor characteristics.
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 significantly improves the light stability of hop extracts, maintaining bitterness and flavor characteristics while reducing the formation of 3-MBT in light-exposed beer.
Implementation Method 1
the alpha and/or beta acids are subjected to photolysis by sunlight, for a predetermined duration, under conditions adapted to produce an optimum quantic yield under suitable temperature conditions
Implementation Method 2
the wort (sugar-rich liquid produced from malt) is boiled with hops before it is cooled down and yeast is added, to start fermentation. Boiling the wort with hops results in the extraction of alpha acids (humulones, such as humulone, adhumulone, cohumulone, posthumulone and prehumulone) into the sweet wort, which under the influence of temperature (thermal isomerisation) are partially isomerised to the corresponding iso-alpha acids
Data Source
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AI summary
The invention relates to a light-stable hop extract comprising at least 1 g per kg of dry matter of one or more hop derived substances represented by formula (I), wherein R = -CH(CH3)2, -CH(CH3)CH2CH3 or -CH2CH(CH3)2. The invention further relates to the use of the light-stable hop extract in beer and to a method of preparing such a hop extract.