In the United States, most consumers choose sliced, wrapped bread from the supermarket. The longer a loaf stays soft and succulent, the more likely it is to be bought, so anti-staling is increasingly becoming a topic in the production process, too. The latest generation of enzyme systems can keep bakery products fresh significantly longer — not only increasing their enjoyment value, but also improving their cost-effectiveness and reducing their environmental impact.
Most U.S. consumers have a clear idea of what their bread should be like: wrapped, sliced, with a high volume and a soft crumb. Bread is bought during the weekly shopping expedition to the supermarket; artisan bakeries play only a subordinate role in the United States.
Large retail chains stock a selection of more than 50 varieties. Besides the classic type made from light-colored wheat flour there are sliced loaves containing rye or wholemeal flour, with grains and seeds, with sour dough, with dietary fibers or oatmeal, in “farmhouse style,” as low-carb or fat-free variants, and many other varieties.
Bread consumption in the United States is currently declining slightly because of a change in eating habits, but bread is still an important staple food that is usually eaten toasted or as a filled sandwich.
Long shelf life urged
There is a great demand in the food trade for loaves with an extremely long shelf life. As a result of hygiene measures, customers can still buy a quality loaf with pleasant freshness and elasticity even days after its production. So the service interval for the shelves can be extended and the return of stale goods reduced. This helps to increase a company’s profitability and improve its sustainability balance.
In the consumers’ homes, it generally takes several days for an opened pack to be used up, so the microbiological and structural stability of the goods is an important quality attribute. However, as far as the fresh keeping is concerned, the right mouthfeel has now become an additional criterion, besides the elasticity and the structure of the crumb. Sensory deficits are no longer accepted. U.S. customers expect the enjoyment value of their favorite bread to remain unchanged for as long as possible.
Measure to optimize shelf life
Preservatives: In order to prolong the service intervals, bakery products must have long microbiological stability. The statutory regulations permit the use of chemical preservatives such as sorbic or propionic acid and the salts of these. But in practice it has to be taken into account that preservatives inhibit fermentation in yeast-risen doughs.
Therefore, they should not be dissolved in the added water too soon and come into contact with the yeast. It is advisable to increase the amount of baking yeast by 20% to 30%.
The addition of preservatives and the high yeast content increase the costs.
From the sensory point of view, too, the use of preservatives has its limits: both sorbic and propionic acid have considerable influence on the smell and taste of baked goods.
Modified atmosphere packaging and clean-room technology: As far as production plant and machinery are concerned, there are a number of ways of prolonging the shelf life and freshness of bakery products. One tried-and-tested possibility is to pack them in a modified atmosphere. In this method, the oxygen in the pack is expelled with the aid of natural gases such as carbon dioxide or nitrogen in order to suppress the growth of mold spores on the surface of the goods for as long as possible. The most reliable form of protection, and the method used in industrial bakeries, is clean-room technology, which ensures that the ambient air is sterile when the goods are packed.
If all the precautions necessary for prolonging microbiological stability are taken, the shelf life of bakery products can be extended significantly. A minimum safe consumption period of up to 60 days for wrapped sliced bread is no longer utopic.
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.