What is the difference between kilning and roasting
I read several posts asking about the difference between crystal and caramel malt. The difference comes from the process to prepare these two kinds of malts. I want to know exactly what is the difference between kilning and roasting. Caramel is prepared by kilning green malt, right? And crystal is prepared by roasting dried malt, right? But what is kilning exactly? Besides, what is the temperature used for kilning caramel malt? It depends on the color of the malt you want, but which is the starting temperature?
Roasting vs. Kilning
There are three main types of specialty malts: color malts (Schreier identifies these as caramel malts), caramel malts (also known as crystal malts), and roasted malts.
Color malts, which have darker wort colors and more intense flavors than brewer's malt, can be be produced in a standard malt kiln, with no roasting.
Caramel malts, which are produced by drying green malt in roasters at temperatures that cause saccharification, essentially have the kilning step replaced by roasting.
Roasted malts, the very dark malts, are finished malts which are further processed in roasters after kilning.
There is frequently some confusion over the words used for the first two groups, color and caramel, which are lighter specialty malts. What European brewers usually call color malts are frequently called caramel or hi-dried malts in the United States. The term "caramel" in Europe is generally reserved for malts that have undergone saccharification during their manufacture. In the United States, these malts frequently go by the name "crystal."
The group known as color malts include a wide variety of products, such as Pale Ale, Munich, Aromatic, Hi Dried, and Vienna. These malts are produced in the same kiln in which brewers malt would be produced, but by using higher temperatures in the cycle, at earlier times, to develop more flavor and color.
The higher the temperature to which malt is subjected during kilning while it is still relatively high in moisture, the more color and flavor will be developed.
In producing color malts, brewer's malt will be kilned in a cycle that begins at about 63 degrees Centigrade for much of the cycle, until the malt is at approximately 10% moisture. Then it will be raised to 71 degrees for two to three hours, followed by three more hours at 85 degrees Centigrade.
In producing Caramel (Crystal) malt, the green malt is sent directly to the roaster rather than the kiln. Low heat is applied during the first part of the cycle to dry off the surface of the grain. Then the grain is subjected to higher temperatures to maximize the activity of the enzymes in the kernel.
After saccarification, the malt is dried to 5 or 6% moisture with higher temperatures. The temperatures may be anywhere from 80 degrees C to 145 degrees C. Colors and flavors are developed during this phase in a way similar to the color malts.
Roasted malts are produced by taking finished malts and further processing them in a roaster. In the roaster the product is subjected to very high temperatures, gradually increasing through the process, as high as 220 to 230 degrees Centigrade. The higher the temperatures, or the longer that the product is exposed to high temperatures, the darker or more carbonized the malt will be.