Malt extract is a product most commonly known for its use in brewing beer. It is available in both a liquid form for the purist, and a dry form for the practical. Both types are produced by first simulating the germination of the barley grain with a process called malting. In this process, sugars are extracted from the sprouted grain and concentrated into an extract.
To begin the process, barley is immersed in water to encourage the grain to sprout, then quickly dried to halt the progress once it begins. Enzymes then begin to break down the starches in the barley and turn them to sugar. This sugar is called malt or maltose. The quick drying step stops the sprouting, but the enzymes remain active.
The next step is to extract the malt sugar from the barley. To do this, brewers use a process called mashing, which initiates the further breakdown of starches. Brewers boil the grain in precisely heated water, dissolving the sugars and pulling them from the solid casing. The liquid produced from this is called wort. Wort is then concentrated by using heat or a vacuum procedure to pull the water from the mixture.
The concentrated wort is called malt extract. When used in brewing, the extract will then enter the fermenting process where yeast catalyzes its transformation into alcohol. Brewers have the option of using a liquid or dry form of extract, and each has its pros and cons, so the choice is solely dependent on the individual's preferences.
Liquid malt extract is a thick syrup. Some brewers choose only to work with the liquid form because they feel it works best for the result they wish to achieve. Also, it requires one less processing step, so it's appealing to those who favor the purest form of product available. Liquid extract is very sticky, however, and therefore messier to work with. It also has a shorter shelf life, and some brewers feel the results are just as good with the dry version.
Dry extract is dried with a special process that removes almost all the moisture content. The biggest advantage to opting for this version is its ease of use. Though it can become stickier when in contact with water, it is easy to measure and requires very little cleanup compared to the liquid version. It also has a much longer shelf life. Disadvantages include a higher product cost due to the extra processing steps, and a more limited list of varieties available.