MALT
So… what is malt? Malting, generically speaking, is when a grain is allowed to begin germination but is then halted prior to the grain fully becoming a “plant”. How is that accomplished? The grain is placed in water to begin the process of germination then dried afterwards. The grain in question - for our purposes - is usually barley, but wheat is also used for certain styles. The process of malting develops the enzymes and starches required for brewing. It’s important to note that unmalted barley, in and of itself, is not suitable for brewing.
The degree to which the barley has been allowed to germinate and develop the necessary enzymes for brewing is referred to as its modification. Fully modified barley malt is typically indicated by an acrospire which is in the range of 75% - 100% of grain length.
Diastatic power is the term used to describe a given malt’s ability to break down long chain starches via enzymes into shorter sugar chains which can be fermented. With that said, this is the appropriate time to distinguish between the two basic types of barley. There is two row barley and six row barley. As the names would indicate, they are descriptive of how the kernels are arranged around the stem of the plant.
Two row malt has a higher extract percentage but a lower diastatic power. Six row malt has a relatively lower extract percentage and higher diastatic power. Because six row malt has a somewhat higher diastatic power, it is used frequently in beers that use adjuncts like corn or rice so that the starches in those adjuncts can be converted to fermentable sugars.
The process of converting the starches found in malt into fermentable sugars is called mashing. The temperature at which this occurs is ~150° F, but malt will convert in the range of 140° F – 160° F. In the 140° F – 150° F range a more fermentable wort will result, but the conversion of starches to fermentable sugars will take longer. In the 150° F – 160° F range the conversion will take place more quickly but there won’t be as complete a conversion and hence, a less fermentable wort will result.
There are two basic methods for mashing. The simplest is the one step infusion mash where hot water is added to the malt and the mix is stabilized at ~150° F while the conversion of starches to sugars takes place. Step infusion/decoction mashing is a method where a small quantity of the mash is removed, boiled, and returned to the main mash in “steps”. The degree of complication you choose for your mashing procedure is fully up to your discretion. Often it’s a reflection of how much time you have available to brew.
With regard to equipment, the vessel in which the mash takes place is called a “lauter tun”. After the mash is complete – usually ~1 hour – the liquid is drained out of the bottom. Following the initial run off, 150° F water is run over the remaining grains to fully wash the fermentable sugars out. This process is known as “sparging”. There are many commercially available as well as homemade contraptions available for this purpose.
If all of this is kind of scary sounding to you, there is a much simpler way to go about it. You can buy malt extract in powder or syrup form where the work of mashing has been done for you. You simply add the extract to the water, boil, and away you go. Mashing, however, provides a fine level of control and a better overall quality of beer. Again, which route you choose – extract or mashing your own – is often a reflection of how much time and effort you wish to dedicate to the process. It shouldn’t be said that extract beers are of bad quality because that’s simply not the case. You can brew an extract beer excellently or an all grain beer poorly. I’ve made many great quality extract brews.
One last point to make here is concerning the use of specialty grains. I’m addressing things like crystal malt, chocolate malt, etc. These are not to be confused with the two row and six row malts I describe above which must be mashed. The specialty grains are usually steeped in hot water and provide flavor and color but not fermentable sugars. Often they are used in conjunction with malt extract to make a beer that has some of the desirable qualities of an all grain brew without the time and special equipment that is required for mashing.