Non-fermentable Sugar – A Vital Component of Brewing

Sugars play a key part in the brewing process and if you are familiar with the basics of fermentation you will know yeasts need sugars for the fuel to keep them working efficiently. As they ferment the sugars in the wort they convert them into alcohol and carbon dioxide.

Low alcohol beers or alcohol free beers will often contain up to 28 g of sugar as it has not been converted into alcohol by the yeast or “fermented” as such.

Most of the sugars used come from starches in the grain which are broken down as the grains are malted, but not all sugars in the grains are fermentable, and understanding the role of non-fermentable sugars in brewing is crucial for achieving the desired flavor and texture in the final product.

You may also want to add sugars to the brew, especially if brewing hard cider, to sweeten the drink or give it a lighter body without the finished brew being like rocket fuel in strength.

What exactly are fermentable and non-fermentable sugars? What are the key differences and what are the best non-fermentable sugars to use in brewing?

What are Non-fermentable Sugars?

pouring some sugar from a spoon into a sugar bowl
Photo by Mathilde Langevin on Unsplash

Non-fermentable sugars are basically sugars that cannot be converted into alcohol during the brewing process. A non-fermentable sugar, while it will not contribute to the alcohol levels (ABV) of the beer, can contribute to the overall flavor and mouthfeel of a beer.

Non-fermentable sugars play an important role in the brewing process, and controlling their levels is key to producing high quality beer.

These sugars are typically more complex and include dextrins, which are large, unfermentable sugar molecules. They are created when the enzymes in the mash cannot break down the starches in the grains into smaller, fermentable sugars.

During the brewing process, the mash is heated to activate the enzymes in the grain, which convert the starches into simpler sugars that yeast can ferment. However, if the temperature is too high or the mash is not mixed well enough, some of the starches will not be fully converted, resulting in non-fermentable sugars in the final product.

One of the primary types of non-fermentable sugars in brewing are dextrins, responsible for some of the sweetness in beer and useful for balancing the bitterness from the hops.

The level of non-fermentable sugars in beer is influenced by a variety of factors, including the types of grains used, the mash temperature, and the length of the brewing process. Generally, darker malts and grains contain more non-fermentable sugars than lighter malts, resulting in a thicker, creamier beer.

Brewers can control the level of non-fermentable sugars by carefully controlling the mash temperature, which affects the activity of the enzymes that break down the starches in the grains.

If the mash temperature is too high, the enzymes may denature, resulting in incomplete starch conversion and higher levels of non-fermentable sugars in the final product.

While non-fermentable sugars are essential for achieving the desired flavor and mouthfeel in beer, too many of these sugars can also negatively impact the final product. High levels of non-fermentable sugars can result in a beer that is overly sweet and has a cloying mouthfeel.

Additionally, non-fermentable sugars can cause problems during the brewing process, such as low alcohol content and poor fermentation.

The higher the amount of non-fermentable sugars, the more full-bodied and creamy the beer will be.

What’s the Difference Between Fermentable and Non-fermentable Sugars?

During the brewing process, fermentable sugars are converted by yeast and other microorganisms into alcohol and carbon dioxide through a process called fermentation. This process is what gives beer its characteristic flavor and carbonation.

The amount of fermentable sugars used in a recipe can impact the final alcohol content of the beer, as well as its level of sweetness, dryness, and other flavor characteristics.

The fermentable sugars are glucose, fructose, sucrose, maltose, and maltotriose, and generally account for 60%–70% of the total dissolved solids in the wort. Mashing conditions that favor the action of the enzymes beta amylase and limit dextrinase in the mash create more fermentable worts. Simple sugars can be added to the wort to increase its fermentability.

Fermentable sugars are classed as including oligosaccharides, disaccharides, monosaccharides and polyols. They are composed of short chains of sugar molecules, making them easy to break down.

Dextrins, by comparison, are polysacherides which have 10 or more sugar molecules joined together in a chain. Yeasts don’t produce enough of the enzymes to break down the chains of a dextrin and therefore they are not fermented or converted in CO2 and alcohol.

Think of it as a steak. When a steak is cut into smaller pieces by your teeth or with a knife and fork, it is easier for the human body to digest. Unfortunately, yeast doesn’t have any teeth or knives and forks, just enzymes which can break down the sugars.

And, even more unfortunately, yeast doesn’t have the required enzymes to break down the dextrins, so they remain largely unfermented and don’t give any extra flavor to the beer (although the undissolved sugars can make a beer sweeter) but can change the body of the beer, making it lighter in some cases.

The Molecular make-up of a Dextrin

Chemical formula of a α-(1→4) and α-(1→6) linked dextrin (such as icodextrin), or of amylopectin
Image Courtesy of Wiki Commons

Non-fermentable sugars do not contribute to the production of alcohol or carbon dioxide during fermentation. Instead, they can impact the body, mouthfeel, and sweetness of the beer. Lactose, another non-fermentable sugar, is commonly used in stouts and porters to add sweetness and increase the body of the beer without impacting the alcohol content.

Some styles of beer, such as stouts and porters, rely heavily on non-fermentable sugars for their signature flavors and textures. These beers are typically made with dark roasted malts that contain more non-fermentable sugars than lighter malts, resulting in a thicker, creamier beer.

To achieve the perfect balance of fermentable and non-fermentable sugars, brewers must carefully control the mash temperature, mix the grains thoroughly, and use the right combination of malts. They may also use different strains of yeast that can better ferment certain types of sugars, or add enzymes to break down the complex sugars into simpler, fermentable ones.

For example, some yeast strains are better at fermenting dextrins than others. Brewers may also add enzymes to break down the complex sugars into simpler, fermentable ones, or they may use a combination of malts that contain both fermentable and non-fermentable sugars.

Should You Add Fermentable Sugars or Non-fermentable Sugars After Fermentation?

It depends on what you want the sugar to do. For affecting the taste or sweetness of the finished beer you should consider adding a non-fermentable sugar or artificial sweetener.

After fermentation is completed, many brewers will add some fermentable sugar to help prime and carbonate the beer via a secondary fermentation. The amount added is so little that it shouldn’t really produce too much more alcohol, just enough C02 to give the beer that essential fizz.

What Are the Best Non-fermentable Sugars for Beer?

The best non-fermentable sugars for beer depend on the style of beer and the desired flavor and mouthfeel. However, there are some commonly used non-fermentable sugars that are popular among brewers.

Dextrins are the most common non-fermentable sugar used in brewing. They contribute to the body and mouthfeel of beer and are responsible for some of the sweetness.

Dextrins are created when enzymes in the mash cannot break down the starches in the grains into simpler, fermentable sugars. Darker malts and grains contain more dextrins than lighter malts, resulting in a thicker, creamier beer.

A commonly used non-fermentable sugar in brewing is maltodextrin. Maltodextrin is a complex carbohydrate made from corn, rice, or potato starch. It is often used in brewing to increase the body and mouthfeel of beer without adding sweetness or altering the flavor.

Maltodextrin is particularly useful in light-bodied beers, such as lagers, where a thin mouthfeel can detract from the overall drinking experience.

In addition to dextrins and maltodextrin, other non-fermentable sugars that are sometimes used in brewing include lactose, glycerin, and xylitol. Lactose is a milk sugar that is commonly used in stouts and porters to add sweetness and increase the body of the beer.

Glycerin is a thick, sweet liquid that can be added to beer to increase the body and mouthfeel. Xylitol is a sugar alcohol that is sometimes used in brewing to add sweetness without contributing to the alcohol content of the beer.

Ultimately, the best non-fermentable sugar for beer depends on the desired flavor and mouthfeel. Brewers can experiment with different types of non-fermentable sugars to achieve the desired result, but it is essential to carefully control the level of non-fermentable sugars to avoid over-sweetness or other issues that can impact the final product.

Is Monk Fruit a Non-fermentable Sugar?

Fructus Momordicae, a kind of Chinese herb for sore throat and hoarseness.
Image from Wiki Commons

Monk fruit sweetener is a natural sweetener extracted from the fruit of the monk fruit plant, which is native to southern China. The sweetness in monk fruit comes from compounds called mogrosides, which are extracted from the fruit using a water-based process.

Dogfish head recently released a low-cal IPA, Slightly Mighty using Monk fruit extract for a low carb, low-cal beer which they boast doesn’t taste like “seltzer water”.

While mogrosides themselves are not fermentable, they are often mixed with other fermentable sugars such as erythritol or dextrose to create a low-calorie sweetener that can be used as a sugar substitute in brewing. However, since these added sugars are fermentable, using monk fruit sweetener as a sugar substitute in brewing may impact the final product’s fermentation and alcohol content.

In summary, while monk fruit itself is a non-fermentable sugar, its use as a sugar substitute in brewing may impact the final product’s fermentability and alcohol content if combined with other fermentable sugars. Brewers should carefully consider the impact of using monk fruit sweetener in their recipes and adjust their brewing process accordingly.

Non-fermentable Sugars – Final Thoughts

Ultimately, non-fermentable sugars are a vital component of brewing that contributes to the body, mouthfeel, and flavor of beer. Understanding their role and how to control their levels is crucial for producing high-quality beer that showcases the unique characteristics of these complex sugars.

By carefully controlling the brewing process and using the right combination of malts, brewers can create a range of delicious beers that highlight the unique flavors and textures of non-fermentable sugars.

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