In our previous release (Enzymes Vol 1) we explored the role of endogenous enzymes in the brewing process. This current release delves into how exogenous enzymes can serve as multifunctional tools for fine-tuning various aspects of brewing. Understanding that brewing largely involves enzyme-induced transformations opens new avenues for optimisation and improvement.
Commercially available enzymes, derived from non-malt sources like bacteria or fungi through controlled fermentation, often come as a mix or blend designed to enhance specific brewing operations or characteristics of the final product. In this review, we go over them naming the most commonly used enzymes. However, they are not limited to the ones we make mention of.
If there is a need to tune an attenuation this group of enzymes will be extremely useful, they break down complex carbohydrates into fermentable sugars, increasing reaction rates, yields, and alcohol levels. They are particularly useful for addressing attenuation variations caused by poor malted grains or inconsistent growing conditions. These factors will affect the protein and carbohydrate content of grains. They can be used for lower-calorie / lower-carbohydrate products, lowering the residual sugar content in beer.
α-amylase
These amylases are added to boost conversion rates within a reasonable time frame
Glucoamylases
Widely used for attenuation control, glucoamylases (also referred to as amyloglucosidases) break down 1-4 glycosidic bonds but not the 1-6 branches of amylopectin. They work best with well-modified malt and can achieve high real degrees of fermentation (RDF). However, brewers must be cautious of glucose suppression, where glucose in the medium inhibits the yeast's ability to utilise other sugars.
Limit dextrins
These enzymes possess the ability to break down the 1-6 branch points of amylopectin. They can be used by themselves or in combination with glucoamylases to accelerate and enhance conversion rates.
High levels of β-glucans and arabinoxylans (cell wall materials ) in wort can cause processing issues and affect the final product's flavour, leading to husky, oxidised, and grainy notes. [1].
Β-glucans and xylanas increase wort viscosity, significantly slowing down the mash filtration process. These compounds adhere to filter aids and filter membranes, and even a presence as minimal as 10% (by molecular weight) can cause filtration issues. Additionally, they bind to starch molecules, reducing their availability for enzymatic breakdown, which can lead to lower brewhouse yields or cause haze. Problems may also occur if the brewer uses specialty grains that lack the necessary enzymes to degrade these molecules. Variations in malt quality, which are common due to several factors, can further contribute to these issues. [3]
β-glucanase:
This enzyme hydrolyses β-glucans gummy carbohydrates, which are a major structural component of the cell wall of barley. The usage of this enzyme can represent cost savings by increasing the yield obtained from filtration operations and reducing operation times.
Xylanases
Also known as arabinoxylanases, arabinoxylans are two pentose sugars arabinose and xylanose. It is an integral component of the structure of the grain and its structure is very similar to β-glucans. Arabinoxylanases hydrolyse pentosans in malt barley, wheat, and unmalted specialty grains. Wheat and rye are particularly high in these molecules. They are also used with or interchangeably with pentosanases, which are highly similar
When using malt adjuncts like corn, rice, or unmalted barley, the free amino nitrogen (FAN) levels can be diluted. Naturally, these adjuncts are non-bearing protein materials and so they water down the overall contents of FAN levels of the process. Adding proteases and peptidases helps increase FAN levels by breaking down proteins into amino acids improving fermentation performance. Proteases can negatively impact foam characteristics if not used carefully. Problems with these enzymes often arise from overdosing or improper use, such as allowing the enzymes to act unchecked for an extended period. However, with cautious handling, these issues can be avoided.
Proteases (Proteinases)
These enzymes break down proteins into smaller peptides and amino acids.
Peptidases
Similar to proteases, they break down peptides into individual amino acids.
Diacetyl is formed from a lateral reaction of amino acid conversion by the yeast. This reaction expels as a by-product of α-acetolactic acid, in solution this compound undergoes a decarboxylation forming diacetyl. Under typical conditions, yeast will re-absorb diacetyl back into the cell through energy-reclaiming processes an enzymatic reaction will convert diacetyl into acetoin and yeasts will again expel the acetoin from the cell, however, the flavour impact of acetoin is way less impactful than those from diacetyl.
Some techniques can be used to control this, however, if experiencing control issues that can't be dealt with such techniques, enzymatic control can be an efficient way to approach the issue.
α-Acetolactate Decarboxylase
This enzyme converts α-acetolactic acid directly into acetoin, preventing diacetyl formation. However, it does not eliminate already-formed diacetyl.
These enzymes can be added post-fermentation, they have a high specificity, and they target a particular sequence of amino acids that tends to be rich in proline. Proline-rich proteins are linked to chill haze formation, these proline-rich regions form the protein-polyphenol complexes that cause chill haze and turbidity issues. If you want to know more about this, click here to look at our previous release ‘Polygel BH’ where we cover this topic.
Proline-specific endoprotease
catalyses a carboxyl-terminal hydrolysis of proline, making it unable to for the problematic protein-polyphenol haze complexes and targeting the degradation of gluten proteins.
Click here to look at our full range of enzymes.
Ana Victoria Vasquez de la Peña
ana@neumaker.com.au
9 July 2024
References
Enzymes - Latest research and news | Nature (no date) www.nature.com.
Control of metabolic pathways using enzymes - Metabolic pathways - Higher Biology Revision (no date) BBC Bitesize. Available at: https://www.bbc.co.uk/bitesize/guides/zwnffg8/revision/3#:~:text=All%20metabolic%20pathways%20have%20to.0metabolic%20pathways%20have%20t
Sammartino, M. (2015) ‘Enzymes in Brewing ’, MBAA, 52(3), pp. 156–164.
Difference between Alpha Glucose and Beta Glucose (no date) Unacademy. Available at:https://unacademy.com/content/neet-ug/difference-between/alpha-glucose-and-beta-glucose/.
Hydrolase - an overview | ScienceDirect Topics (no date) www.sciencedirect.com. Available at: https://www.sciencedirect.com/topics/biochemistry-genetics-and-molecular-biology/hydrolase.
Bank, R.P.D. (no date) RCSB PDB - 1AMY: CRYSTAL AND MOLECULAR STRUCTURE OF BARLEY ALPHA-AMYLASE, www.rcsb.org. Available at: https://www.rcsb.org/structure/1AMY?assembly_id=1 (Accessed: 2 July 2024).