Malt - Understanding the role of Malt in European Rye Breads
Best link I have found explaining the role of Malts and Rye:
What is Malt?
"When grains (or most of seeds in general) are soaked in water, they start to germinate. This is the first stage of a growing process of a plant. Germination process develops enzymes, which start to break down complex saccharides like starches into simpler ones like sugar and glucose. The same is true for complex proteins present in the grains as well. Simpler variations of carbohydrates and proteins are then used as an energy source and building blocks for a new plant.
Malt is made when this process is halted midway to stop grains from growing into new plants. This allows us access to all of the enzymes which became available. These enzymes can then be used in multiple different ways for all kinds of products, including bread and beer."