Malting begins by soaking the raw barley. It is dumped in steeping tanks where it spends a couple of days soaking up water. The barley is then transferred to a huge room where it is aerated and held at around 60 degrees Fahrenheit. It is also regularly turned This is all done to encourage the grain to sprout without putting down roots which it does in around five days. It is now called green malt.
The maltsters then kiln or dry the green malt by slowly raising the temperature to over 120 degrees Fahrenheit. The final temperatures vary depending on what kind of malt they want in the end. The result, however, is the same, regardless of the final temperature - the growth of the sprouts is stopped.
That is because the maltster has what he is looking for, a dried barley grain full of sugar, starch and a particular kind of enzyme called diastase. After the grain is transferred to the brewery the brewer will add the grain to hot water. This will encourage the diastase to convert the starch into simple sugars. Once those sugars are dissolved in the hot water, the brewer will have her wort and she will be ready to make beer.