Reader Evan asks:
How do additives (either traditional like fats or modern) slow staling?
That’s a great question, Evan. The answer is that the way in which additives inhibit staling isn’t always well understood, which shouldn’t be surprising because the chemistry of bread isn’t all that well understood either. Still there are some pretty good theories out there.
We’ve talked before about crystallization, which happens when similar molecules start stacking up on each other like LEGO’s. Crystallization is the phenomenon primarily responsible for the hardening of bread starch (i.e. staling). Thus it stands to reason that if you could somehow stop wheat starch crystals from forming, or at least slow that crystallization down, then you’d keep bread fresher for longer.
One of the ways you do that is by introducing other types of molecules that physically insert themselves between the starches, keeping them from locking together. Emulsifiers like lecithin do that. Emulsifiers tend to be rather small as molecules go, and do a pretty good job of gunking up the works.
Another way to go is to mess up the starch molecules themselves to one degree or another so they don’t fit together as well. Enzymes like alpha amylase do that, breaking pieces off of long starches to that they don’t fit together as easily. The pieces they break off also do a nice job of getting in the way of starches as they seek to lock together.
Other anti-staling agents don’t physically inhibit the molecules but rather make them less (literally) attractive to one another. Acids do this, as do fats, or so it’s thought (lipids are, after all, “fatty acids”).
Still other strategies all but ignore the crystallization process and simply seek to add moisture to the bread so it at least has the impression of freshness. Added fats, for instance, make bread feel tender in the mouth even if the starches they surround are a little on the firm side. Seed coat gums like pentosan gum do a similar job. If you’ve ever wondered why rye breads or whole wheat breads stay fresher longer than simple white breads it’s because of those gums. Black bread can stay fresh at room temperature for a week or more. However lots of moisture is a double-edged sword, as it promotes the growth of mold.
Huh…seems like we need some more additives here…