Various substances and additives that somewhat slow down the staling of bread
Staling of bread is its most unpleasant drawback, which sharply reduces the consumer properties of bakery products. Extending the freshness of baked bread is the most urgent task for baking practitioners and scientists. At one time, many dissertations were defended on this subject, but in practice, the freshness of bread in stores does not exceed 30-40 hours, that is, two days.
The mechanism of staling is determined some changes in the starch of the bread during its storage, as well as some changes in the protein of the bread. The starch of the flour gelatinizes during baking, softens, absorbs and binds water. The longer the moisture stays in the bread, the longer the bread will stay fresh. During storage of bread, starch begins to retrograde - to restore hydrogen bonds between chains of oligosaccharide residues. Starch loses previously bound moisture, starch is saccharified, its grains decrease, harden, the crumb of bread begins to crumble, the bread becomes stale.
During storage of bread, significant changes also occur in the protein substances of the crumb. When bread is baked, the phenomenon of protein denaturation occurs, and when it is stored with protein, the opposite occurs. Protein in the crumb of bread is much less than starch, and changes in protein are several times slower. Therefore, the contribution of changes in starch to the process of staling of bread is an order of magnitude greater than the contribution of changes in protein.
For a long time, bakers have added various substances and additives to the dough, which somewhat slowed down the staling of bread. These additives included four main groups of ingredients:
- substances that slow down the saccharification of starch;
- substances that bind moisture in bread;
- substances that change the structure of the protein (enzymes);
- natural preservatives.
Over the past hundred years, almost nothing has changed, only special types of packaging have been added, which also reduce the loss of moisture in the product and slow down the celebration process.
Various chemical and natural ingredients are added to the dough as preservatives, which effectively suppress the development of whitish bacteria and mold fungi. Such preservatives include the widely used sorbic acid and its salts (E-200, E-201, E-202, E-203). Sorbic acid is found in some berries and fruits (cranberries, mountain ash) and has been used as a preservative since antiquity. Abroad (in our country less often), propionic acid salts (E-281, E-282, E-283) are also widely used. In general, all food acids affect the staling process: tartaric, citric, and lactic.For example, rye bread and mixed roll varieties are known to be less prone to staleness than wheat bread. Their acidity is much higher (lactic acid when fermented), which helps to extend the freshness. Ascorbic acid (E-300 vitamin C) and some of its salts are often used, which are also good antioxidants that smooth out the effects of contact of the crumb of bread with atmospheric oxygen.
Enzyme additives are widely used to slow down the staling process. To slow down the saccharification of starch, starch-splitting amylase preparations are added; fungal proteases are also used, which partially destroy the bonds in the protein structures of the crumb. In order to influence gluten protein molecules, additives in the form of bacterial proteases and papain are used. Most often, these preparations are contained in special enzymatic or complex bread improvers. Significant amounts of enzymes are found in soy flour and malt, which have long been added to bread by bakers.
Additives that greatly slow down the saccharification of starch. These mainly include glucose, which prevents the formation of hard sugar crystals. Glucose is found in significant quantities in special syrups that are used in the confectionery industry and in bakery. The addition of glucose syrup (content of pure glucose 45%) in an amount of 5-6% to the weight of dry flour, allows you to increase the freshness of the bread by more than two times. In Russia, cheaper molasses is more often used, in which there is much less pure glucose than glucose syrup. Some types of bread, in which molasses (glucose) is added according to the recipe, are famous for prolonged freshness (Borodinsky, Orlovsky). Various infusions (in custard varieties) are a method of saccharification of starch, a method of increasing the fementative activity of the dough, thus helping to prolong the freshness of the products.
Additives that bind water in bread, prevent intensive drying (staling). The use of jelly-forming substances (thickeners) is very effective, they bind water in bread, the moisture content during storage does not decrease so intensively, it does not dry out. Natural thickeners include carrageenan and its salts (E-407), Agar (E-406), gums, pectins (E-440). In bakery, low-esterified pectins are most often used, the addition of which to the dough in an amount of 0.1-0.2% allows not only to significantly prolong the freshness of the bread, but also to increase the yield to 5-6% due to the large amount of bound moisture. The addition of gluten concentrate to the dough is very effective, which binds water about 2-3 times its own weight. Gluten concentrate is added in the amount of 2-3% by weight of flour, increases the percentage of gluten in the dough by 5-7%, binds about 8% of water.
Another way to bind moisture in bread is additives of various types of emulsifiers. There are a lot of them, so we will not list them. The most famous is lecithin. This substance is found in significant amounts in egg yolk, so bakers and pastry chefs add eggs to baked goods to increase the ability to knead "heavy" pastry dough (emulsifier) and prolong the freshness of the product (moisture binding). Emulsifiers work especially well in doughs with a lot of fat. It is well known that even with prolonged agitation, water and liquid fat do not mix. In order to combine water and fat, the emulsifier must be composed of two molecules. One molecule is attracted by water, the other by fat. Thanks to this feature, the emulsifier combines water and fat, becoming a mediator. A lipophobic molecule attracts water, while a hydrophobic molecule attracts fat. Water and fat are thus bound by the emulsifier. The fat, in turn, also contributes to the elasticity of the crumb, since it softens the connection of the starch grains with the gluten framework. Adding up to 3% fat to the dough also prolongs the freshness of the bread to a certain extent.
There are also some other dough additives that perform similar functions, or a combination of such functions. There are many improvers that, among others, perform freshness-prolonging functions. However, no one has yet reached a complete solution to this problem. Very complex processes take place in the crumb structure, a lot of factors affect this. Moreover, you should not look for a "drug" that will completely solve the problem of stale bread, you should also not believe the advertising statements of some manufacturers that only their improver prolongs the freshness of bakery products.