It’s not a fundamental ingredient of bread.
It is used when you want the bread to be sweet, festive, or have a more attractive crust colour. Small amounts of sugar help retain moisture so crumb is softer and crust tender. This bread keeps fresh for a longer time. Sugar is especially important in whole wheat bread.
Sugar and sweet juices of certain fruits are important in bread made with natural yeast because they are additional food for the yeast and help the fermentation process.
White sugar may be alternated with brown sugar (unrefined cane juice), with honey, maple syrup, grape juice or other sweet fruit. Syrups, honey and molasses have a high water content, so that its capacity to sweeten a dough is lower by weight than solid sugar. To use such liquid products we’ll have to increase the amount of sugar the recipe calls for and reduce the amount of water in the dough.
Maltose is a natural sugar that is formed in the dough due to the action of certain enzymes called amylases which come with the grain and cause large starch molecules to split into smaller ones to form maltose.
The amount of maltose in the dough increases with the time the dough is resting. Not all flours have by nature the same amount of enzymes. Hence, the colour of the crust after baking is not the same with every flour. Some poor flours are usually enriched with the addition of enzymes or just a small amount of malted barley. If your flour produces a pale and sickly crust colour, you can improve it by adding small amounts of Malted Barley Flour. In doing this you must be very careful not to add too much as excess maltose ruins the dough. You can try with 1 or 2 teaspoons of malted barley flour, also called malt flour, per kilogram of flour in the mixer. If the crumb in the baked piece is sticky, you added too much malt. Next time try less. The amount required depends on the flour you use. The right amount of malt has to be found by personal practical experience.
You can also use Malt Extract, which is maltose in the form of a thick and sticky dark brown honey. Malt extract is not an active enzyme but only a concentration of maltose. Use it the same way you use sugar or any other ingredient. Time has no effect on malt extract.
In the place I live, I find it quite difficult to find malt extract on the market. It can be found in beer brewery stores, but not always plain. It generally comes added with hops giving the malt extract a strong bitter taste.
It is possible to make homemade malt extract. In another article (in process) on this site, I present an easy procedure to make it at home.