What is Malt?
Most likely, you’ve heard malt or malting in reference to beer, but have you ever wondered exactly what malt is?
In general, the subject is malted barley. Malting is the least-familiar part of the beer brewing process, since you won’t see it on a brewery tour. Very few brewers do their own malting but rather rely on maltsters with specialized knowledge, equipment and facilities to produce this crucial ingredient.
Least familiar, perhaps, but quite fascinating, because it harnesses the barley plant’s natural enzymatic processes of converting starch to sugar. The sugars extracted from germinated barley feeds yeast and induces fermentation.
It begins with the selection of barley variety. Brewers generally specify (or work with maltsters to choose) certain barley varieties for a particular influence on their processing and/or finished product. Any new varieties are tested for as long as 10-12 years before being deemed suitable for malting. Maltsters require delivery in pure lots, by season and by growing region; this careful segregation carries through the entire process and ensures consistent, reliable, expected properties for brewing.
Incoming barley is also meticulously inspected for quality and tested for fungal mycotoxins such as deoxynivalenol (DON). Sprouted, damaged, or immature kernels; foreign material; and fungal infections and diseases can at the very least produce poor malt, and at worst be toxic.
The malting process itself starts by steeping barley in water for a couple of days. Experienced maltsters have a deep knowledge of all the factors that determine the exact soak time. It is then laid out in a huge room where it is turned regularly for aeration and to maintain a constant temperature, usually around 60°F. This encourages the barley kernels to sprout or germinate.
As this point, enzymes start converting the kernel’s starch reserves and proteins into amino acids and sugars intended to help the barley plant grow. The trick is to stop the germination process at just the right point so that the kernel retains the optimum level of each to contribute to the final product.
To stop germination, when the time is right, the kernels are kilned (dried) by slowly raising the temperature to a point at which the process is stopped. How high that temperature is determines the kind of malt produced. In general, the higher the temperature, the darker the malted barley, and the darker the beer will be in the end. Finished malt may then also be roasted at even higher temperatures to affect the darkness and even carbonation of the final product.
The maltsters’ finished product is a dried barley grain full of sugar and starch. Once delivered to the brewery, it is added to hot water to convert the remaining starch into simple sugars. The sugars dissolve into the hot water and can be easily accessed by the yeast to begin the fermentation process.
With the brewers controlling the mixing and matching of ingredients, they rely on maltsters to provide malt with reliable and specific physical and chemical characteristics in order to ensure consistency and quality, in their processes as well as their final product.
Photos courtesy of Allagash Brewing Company, Portland, ME.