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  • Bob Monroe

The Complexity of Simple Sugars

The process of brewing begins with the extraction of various types of sugars from malted barley. The types and quantities of sugar extracted depends on the malt being used and adjustments in the mashing process (more to come on this in a minute). As I prepared to conduct my first non-alcoholic beer test batch, the majority of my focus was around how to manipulate the inputs to create the right amount of sugars in the correct ratio in order to produce a beer with less than 0.5% alcohol by volume.

God Made Barley for Beer

The only thing barley is really great for is brewing beer. Sure, it can be used in small quantities in bread or soup, and can be fed to livestock, but beer brewing is really where it shines. I know that God made barley for brewing beer because it contains everything needed to produce beer right inside its little kernel, namely starch and enzymes.


Mashing is the first step in brewing beer in which malted barley is crushed and then mixed with hot water. The crushing, or milling, of the malted barley exposes the starches inside the kernel, the hot water then gelatinizes (liquifies) the starches and activates the enzymes that are present in the malt.

The starch in malt is a complex carbohydrate made up of multiple glucose molecules joined together. Most beer yeast cannot consume complex carbohydrates and this is where the enzymes, which are conveniently already present in the malt, start to work their magic. Enzymes go to work and start to break the bonds between glucose molecules creating several types of sugars depending on how many glucose molecules are left bonded together after conversion.

This table shows the types of sugar created during the mash:

Number of Glucose Molecules

Type of Sugar


Single Glucose Molecule


Simplest sugar created

Two Glucose Molecules


The most common sugar in wort

Three Glucose Molecules


Fermentable by most but not all beer yeasts

Four or More Glucose Molecules


Not fermentable by most beer yeasts


There are two primary enzymes found within malted barley and each behaves a little different. Alpha amylase works most efficiently at higher temperatures (158 degrees Fahrenheit) and breaks the bonds between glucose molecules at random points. Because the enzyme acts randomly it results in mix of all the possible sugars and dextrins.

The other main enzyme is beta amylase which works best at lower temperatures (145 degrees Fahrenheit) and acts in a very systematic way by breaking off the last two glucose molecules at the end of starches. Because of this only maltose is created by beta amylase.

Because each enzyme works best at different temperatures, by altering the temperature of our mash we can control which enzyme dominates and in turn the mix of sugars created. Lower mash temperatures which favor beta amylase results in a larger percentage of maltose which is easily fermented by beer yeast. Mashing at higher temperatures favors alpha amylase and results in a more diverse mix of sugars and also dextrins which are not fermentable by beer yeast. The brewer adjusts the mash temperature in normal brewing to control the fermentability of the wort and how much body the resulting beer might have. Similarly, we can use mash temperature to help us achieve our goals in non-alcoholic brewing.

Mash Efficiency

Another important concept to understand before we design our first brewing trial is mash efficiency, which is how well we are able to extract the available sugars (and dextrins) from the malted barley. Due to inconsistencies in the mash, temperature fluctuations, water chemistry, and a myriad of other factors we’re never able to extract 100% of the available sugars from the malted barley. To reduce the amount of malt needed and keep our costs down, it is always our goal to get as high an efficiency as possible, unless possibly you’re trying to make a non-alcoholic beer.

Other Controls

There are also a couple other simple ways to control how much sugar is extracted and how much is then consumed by the yeast. The easiest way to reduce the amount of sugar in the wort is to reduce the amount of raw materials used in the mash, in other words just use less malt.

Another straightforward way to control how much sugar is consumed during fermentation and thus how much alcohol is produced is through yeast selection. While almost all beer yeasts are capable of consuming glucose and maltose, not all of them can consume maltotriose. We term these strains of yeast as maltotriose-negative. Because these yeasts cannot consume maltotriose less alcohol is produced. You might also hear this described as low attenuation where attenuation refers to the percentage of all the available sugars consumed during fermentation.

There has also been a lot of talk recently in the brewing world about maltose-negative yeast which can only consume glucose and leave everything else behind. These yeasts exhibit extremely low attenuation and can be particularly useful in the production of non-alcoholic beer.

Putting It Together

If I have not put you to sleep yet stay with me cause we’re about to put it all together. So, if we wanted to put together a formula for making a non-alcoholic beer it might look something like this:

Low sugar content + low mash efficiency + low fermentability + low attenuation = very low alcohol (<0.5%)

We’ll try to achieve each of these through our recipe formulation, ingredient selection, and process adjustments. For my first brewing trial I plan to tackle each of these as follows:

Low sugar content – Use around 20% of the malt I would use for a regular strength beer.

Low mash efficiency – Mash for a shorter amount of time, at a higher temperature, and with a greater percentage of malts with low diastatic power (the amount of enzymes present, more on this in a future blog).

Low fermentability – Produce a wort with a higher percentage of maltotriose and dextrins by mashing at extremely high temperatures which favors alpha amylase.

Low attenuation – Ferment with maltotriose-negative or maltose-negative yeast strains (I actually intend to try both).

So, for my first trial I will mash a small amount of malt at extremely high temperatures (~170 degrees F) and then ferment with two different strains of low attenuating yeast. The main goals with the first trial will be to figure out my new homebrew equipment, confirm some of the theoretical concepts above, and gauge whether it will even be possible to create something worthy enough to serve at Figurehead.

Next: Let the trials begin!



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