What does kilning do to the green malt aside from drying it?

Kilning is a crucial process in malt production, and one of its key functions is to develop the color and flavor of the malt. During kilning, the green malt is not only dried but also subjected to heat that causes various chemical reactions. One of the most significant outcomes of this heating process is the production of melanoidins, which are complex compounds formed from the Maillard reaction between sugars and amino acids. These melanoidins contribute to the malt's color and flavor profile, resulting in the rich browns and ambers often desired in various beer styles.

The other options don't accurately describe the primary effects of kilning. While kilning does create a drier product and can affect enzyme activity, it does not significantly enhance enzyme activity; in fact, too much heat can denature enzymes. Also, kilning does not notably increase sugar content; that development occurs mainly during germination as the starches convert to sugars. Lastly, while kilning can offer some degree of protection from microbial contamination due to drying, it is not its primary function and should not be considered a principal outcome of the process.