Retrogradation starts immediately after baking

For bakeries, it is a major challenge to curb the natural aging process of bread, for in light-colored wheat loaves retrogradation starts immediately after baking. The processes underlying the loss of freshness are caused mainly by redistribution of the moisture between the crust and the crumb and structural changes in the starch.

The most important factor is the interaction between the starch and the water added for making the dough: during baking, the starch gelatinizes, and in this condition, it binds the water in the dough. But the process is partially reversible. As soon as the bread is taken out of the oven, the starch has a tendency to return to its crystalline structure, binding the water firmly. The longer the bread is stored, the less free moisture is available to the crumb; it becomes tough and chaffy and feels dry when chewed.

Bakeries have various possibilities of counteracting retrogradation and optimizing the fresh keeping of the products.

Dough processes: The higher the dough yield, the longer a loaf remains succulent. Therefore, dough processes should be cool, soft and long in order to allow intensive swelling and binding of the water. But the water content can be increased with a sponge dough, too, and the flavor enhanced. The addition of hydrocolloids with a high water-binding capacity (e.g. in the form of guar gum powder, potato granulate or dietary fibers) also can be recommended from the point of view of anti-staling.

Another reliable method is the addition of “left-over bread.” This is unsellable but completely hygienic bread, usually losses from breakage or slicing that can be returned to the dough up to a certain quantity. The gelatinized starch has a positive effect on the binding of water, and at the same time the aromatic substances enhance the flavor. To prevent the appearance of coarse particles in the crumb, the bread is first dried and ground, then mixed with water to form a slurry. Alternatively, the loaves can be broken up in a wet grinding process and mixed into a moist, homogeneous mass.

Enzymes: Enzymes specifically designed to optimize the quality attributes “crumb structure” and “chewing feel” play a key role in extending the shelf life of bakery products.

In most cases these enzymes are maltogenic amylases (e.g. Sternzym Fresh), an important attribute being that they remain active during and beyond gelatinization of the starch and are only inactivated at temperatures above approximately 70 degrees C.

This gives them more time to act on the starch during the baking process. As a result, retrogradation is considerably inhibited and the fresh keeping prolonged.

Maltogenic amylases often are used together with or instead of emulsifiers like mono- and diglycerides or stearoyl lactylate.

The new generation of maltogenic amylases has a broader functionality. Whereas classic maltogenic amylases counteract solidification of the crumb structure, the new specificities also help to maintain the succulent chewing feel for several days or even weeks (e.g. Sternzym Fresh 86). Because of this, the crumb of a loaf does not taste dry, brittle or insipid even after a considerable storage period; it still offers a fresh, succulent mouth feel.

Today’s manufacturers therefore have a number of different possibilities of producing quality baked goods economically and with a minimum of waste.