Next to yeast, the most important ingredient in any type of brewing is a source of sugar. Without sugar, there is no brewing. The sources of this sugar can be as varied, but without some form of sugar, fermentation becomes impossible. Before we get into the different sources of sugar, we should first describe the different types of sugar.
Types of sugar
There are three different forms of sugar: glucose, fructose, and sucrose. Glucose comes from breaking down starches into sugar by use of an enzyme called amylase. Fructose is the natural forming sugars in most fruits, like grapes. Sucrose usually comes from evaporating the sugary sap found in plants like sugar cane and sugar beets.
Sources of sugar
The source of sugar that most beer and ale brewers are familiar with comes from some type of grain, usually barley. The process of forming this sugar comes from taking the malted grain and steeping in hot water during the “mashing” process. The enzymes that are in the mashing bath convert the starches in the grains into sugar required for fermenting.
Another source of sugar comes from fruits used in brewing. Grapes are normally the first fruit that comes to mind since it’s the primary component of wine. The mashing and pressing of the grapes releases the sugar rich juices, which then proceeds to get fermented to create wine.
Sugar in fermentation process
This brings us to the main reason for home brewing. Fermentation is the process of converting sugar into alcohol by use of yeast. In an oxygen poor environment, yeast eat the sugar and expel Carbon Dioxide (CO2) and alcohol. Fermentation takes place until the yeast die. The two primary situations that cause the yeast to die is starvation or the level of alcohol in the wort is high enough to poison them.
In the first situation, where they die from starvation, is caused by not having enough sugar available for the yeast to keep eating and reproducing. What this means in more practical terms is that, with all the available sugar being converted to CO2 and alcohol, your final resultant brew is going to be less sweet and dry. It’s also going to have a lower alcohol content since more alcohol could have been produced if more sugars had been available to convert into CO2 and alcohol.
This brings us to the second situation, which could be thought of as having too much sugar in the fermenting liquid. What happens in this situation is the yeast keep eating the available sugar and multiplying while also generating the alcohol and CO2. What’s different in this situation is that the yeast continue to create alcohol until it reaches a level toxic to them. This causes the yeast to die off while still leaving sugars available in solution. This remaining sugar makes the resultant liquid sweeter. It also means there’s no way to make a drink with a higher percentage of alcohol content without using the process of distillation.
Sugar as a flavoring agent
A final area that sugar plays a role in brewing comes from its use as a flavoring agent. The best example of this is in the brewing of mead. In its most basic recipe, all that’s required is honey, water, and yeast. The honey is the main source of flavoring. Another example is using maple syrup as an ingredient in brewing beer. While the primary flavoring agents are the grains and hops, there is a distinct flavor difference to the resulting beer if maple syrup was used as an ingredient.
This all comes back to the most important thing to keep in mind. If there’s not enough sugar available for the yeast to eat, there’s not going to be much brewing going on.