Pav Improvers

The use of improvers in the production of baked goods is common practice today. It is also part of the technological effort to produce baked goods from wheat flour that have high sensory, practical and nutritional value. Besides the use of machines for dough and batter make-up, processing and baking, improvers are used specifically to improve production methods and the quality of bakery products.

According to the definition laid down in the German Guidelines for Bread and Small Baked Items, improver are mixtures of food including additives intended to facilitate or simplify the production of baked goods, to compensate for changes in processing properties due to fluctuations in raw materials and to influence the quality of baked goods. Improvers are made from food (cereal products such as starch, malt, different sugars, dairy products such as powdered milk, soy flour, …) with or without additives (preservatives, fruit acids, phosphates, thickening agents, …), depending on the relevant application. The substances used for improvers are often also components found in the food product that is being made with these improvers.

Improvers can be composed differently depending on the product to be used in or on the intended production method. They belong to either one of the following groups:

Production processes: (Common for all baked goods)

Only milled grain products from wheat and rye can be used to make products according to the above scheme. Milled products from other types of cereal such as rice, barley, oat or corn will not yield proper dough when combined with liquid. These results in products with a low increase in volume, hardly any browning and which, in addition, are hard to cut, spread and chew. On the other hand, milled wheat and rye products in combination with liquid will yield visco-elastic dough which retains the gas from the yeast fermentation (CO2) in the form of tiny bubbles. In wheat dough, the so-called gluten is responsible for that. This protein absorbs water and forms an extensible and elastic membrane which encloses the gas bubbles. In rye and wheat doughs, the gas is retained due to the high viscosity of swollen gum-like substances (pentosanes) present in the dough. However, the gas permeability of the mass surrounding the gas bubbles is higher in rye dough than in wheat dough. Therefore, rye-containing baked goods have a lower specific volume than wheat dough products.

In wheat flour products the protein gluten is mainly responsible for the formation of dough. The amount of gluten, its water absorption capacity as well as its elasticity and extensibility define the processing properties of the dough. Gluten encloses the gas-containing pores in the dough and is thus responsible for the gas retention capacity of the dough and therefore for the volume of the baked good. The quality of the gluten dictates how much gas is retained in the dough. The main component in flour is starch which is present as lentil-shaped granules.

During the baking process, starch swells and partly gelatinises by absorption of the water previously bound to gluten or pentosanes during dough preparation. The swollen starch granules form the crumb structure in the finished baked good, a small portion of the starch granules will be mechanically damaged during milling of the grain. The damaged starch will absorb a greater amount of liquid during dough preparation and can be attacked by amylases.

Enzymes are other ingredients important for the baking process. They are located in the outer layer of the grain kernel. Amylases degrade starch to dextrins and then further to fermentable sugars. An excess of alpha-amylase activity in the dough may result in increased starch degradation during the baking process which impairs the crumb formation. This results in an inelastic, sticky crumb. An increased alpha- amylase activity can be observed if the grain kernel is damaged by pre-harvest sprouting. This can happen if the ripe kernel takes up water during instances of prolonged rainfall. In particular, rye is susceptible to premature sprouting due to the short dormancy and because the kernels are not completely protected by the husk. This phenomenon is called sprout damage.

Influence of improvers on the baking properties of milled grain products, white wheat flours, used for production of small bakery items, contain only low levels of alpha-amylase because the enzymes is located beneath the hull of the grain which is removed during milling. In the 19th century it was established that the inclusion of flours made from sprout-damaged grains into wheat dough increased the volume of the baked goods. Some years later, flour from artificially sprouted grains (malt) was used as source of amylase. Today microbial amylase preparations as well as malt flour are used. Amylases have two important effects on the volume of wheat based bakery items.

During the dough phase, amylases partly degrade the damaged starch to fermentable sugars. These, in turn, will be converted into alcohol and carbon dioxide by the yeast and ultimately contribute to the leavening of the dough. The main effect of the alpha-amylases, however, takes place during the baking process when the gas bubbles in the dough expand because of the temperature increase (oven spring). This thermal expansion is counteracted by the increasing viscosity of the starch which is simultaneously absorbing water, swelling and partially gelatinizing. Selective use of amylases can decrease the viscosity of the starch enabling greater expansion of the gas bubble at the start of the baking process.

Amylases also have an effect on the browning of the crust (bloom). Dextrins and sugars formed during the enzymatic degradation of starch give rise to the formation of a brown colour during baking and the typical bread flavour develops as a result of the reaction between these ingredients and other dough components.

Finally, the starch quality also influences the staling of baked goods. With selective use of amylases, the starch structure can be altered and the shelf life of the baked goods prolonged.

Flour also contains water-insoluble hemicelluloses originating from the walls of the grain cell. By adding xylanase these materials can be converted into soluble, gum-like substances which bind water resulting in an increase in dough strength as well as improved dough processability. The risk of dough sticking to machine parts and causing production problems can be minimized in this way. The absorbed water migrates into the starch during the baking process causing a decrease in viscosity and resulting in an improved oven spring and higher volume for the baked goods.

Protein degrading enzymes (proteases) are used for improving the processing properties of doughs made with flours containing strong gluten with low elasticity.

Lipoxigenases oxidise lipids present in the dough. They are added as part of an enzyme-active (I.e. not heat processed) soya flour and are used for brightening the crumb (through oxidation of yellow carotinoids) of toast brad.

Emulsifiers are other ingredients found in improvers. Gluten, important for the technological baking properties of wheat flour, contains certain surface-active lipids (emulsifiers) originating from the cell membranes of the wheat kernel (galactosylmono- and -diglycerides) and these contribute to the functional properties of gluten. Dough properties can be further improved by the addition of specific emulsifiers. Lecithin, diacetyl tartaric acid esters of mono- and diglycerides as well as stearoyl lactylate are all used in improvers. These emulsifiers improve the gas impermeability of the membrane that encloses the gas bubbles. This makes the dough less susceptible to mechanical stress during dividing, moulding and handling. Proofing stability as well as oven spring will also increase. Monoglycerides of fatty acids and starch will form so-called "inclusion compounds" which prevent the recrystallisation of starch (retrogradation) in the finished baked good. Retrogradation being the main cause of staling.

Other components in improvers are ascorbic acid and cysteine. After enzymatic conversion of ascorbic acid into dehydroascorbic acid, this substance acts as an oxidising agent and improves gluten quality and dough stability. The amino acid, cysteine, also reacts with the gluten, but by softening the dough and making them smooth and easy to process.

The acidifiers mainly consist of lactic, acetic or citric acids or acidic phosphates. The acids cause a reduction in pH in the dough which inhibits the action of alpha-amylases.

Staling of wheat bread is often experienced as a firming of the bread crumb during storage. This process can be retarded by the inclusion of monoglycerides of fatty acids, stearoyllactylate and/or water-binding/swelling agents such as guar gum or locust bean gum. (Freshkeeping agents) Improvers are also used in production of yeast-raised or chemically leavened fine bakery wares. In yeast-raised fine bakery wares, the same additives can be used as for wheat bread dough because the same effects can be achieved. In chemically leavened fine bakery wares, however, improvers are mainly an aid to facilitate the production of the dough / batter. Diglycerols esters of fatty acids are responsible for air incorporation, because they are able to uniformly distribute the air introduced into the batter during whipping and to stabilize the resulting gas bubbles.

Application of Improvers:
Improvers are generally used at an amount of no more than 10 % calculated on flour. Depending on the purpose, they contain an optimum amount of components. They are commercially available as powder, in granular form.

Optimization of dough properties:

Optimization of the fermentation process :

Control of proofing time (retardation and interruption of proofing time):

Improvement of baked goods properties:

Simplified preparation of doughs and batters:

The fact that no individual substance is able to fulfill all the tasks by itself is clearly demonstrated in the example of the effects that improver components have on the volume of small bakery items made from wheat dough.

Improvers have become an essential component in the recipes for baked goods. This will not change in the future because of the strong influence and important role that milled grain products, as major recipe components, will play in further developments within the baking technology sector.