STALING is the act of retrogradation, gelatinized starch molecules forming and realigning crystalline regions, causing the liquid to gel over time. In bread, specifically, gelatinization occurs during baking when the interior of the loaf reaches a certain temperature, and the dough forms a solid matrix, creating what is known as the crumb.
After gelatinization, the amylose (helical component of starch, making up approx. 20-30% of structure) molecules rapidly form helices, packed tightly, making a compact and firm bread creating the sense of moisture loss. This process also decreases the digestibility of starch, thus coined Resistant Starch, which escapes the small intestines intact, where is it extensively fermented by microflora in the large intestine into short chain fatty acids (acetate, butyrate, propionate, etc). SCFAs help lower the pH of the gut and improve colonic and systemic health.
After the initial rapid retrogradation, the process is slowed due to the structure of amylopectin (branched component of starch, making up approx. 70-80% of structure). The temperature at which retrogradation occurs the fastest is that just above freezing, so avoiding the fridge is ideal. Rather, store at room temperature or freeze. Although the refrigerator inhibits mold, so do the bacteria found in the sourdough culture.
If STORING bread at room temperature, you can simply leave it on the counter, with the cut side face down to reduce open contact with air. Otherwise, kept in cloth or a paper bag works well. Storing bread in an airtight plastic bag will increase chances of mold and soften the crust due to minor (less than 1.5% water loss) condensation.
Reheating bread temporarily reverses the actions of starch retrogradation, disrupting the less stable crystalline regions, and releasing trapped molecules of water.
If storing bread in the freezer, store in a plastic bag, sliced or whole. If sliced, simply reheat in a toaster. If whole, thaw overnight and reheat at 170˚F for 15-20 minutes.
Run the TOASTER empty a few times until it’s red hot. Drop in a slice of thick toast and proceed as normal. This will result in a soft silky interior with that great crunchy, toasty bite. Respect the bread!