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The baking industry is paying increased attention to consumers seeking gluten-free products. In fact, sales of these products is on the rise. Coeliac disease is a common digestive condition where a person has an adverse reaction to gluten. Coeliac disease isn't an allergy or an intolerance to gluten.

In cases of coeliac disease, the immune system mistakes substances found inside gluten as a threat to the body and attacks them. This damages the surface of the small bowel (intestines), disrupting the body’s ability to absorb nutrients from food. Exactly what causes the immune system to act in this way is still not entirely clear, although a combination of a person's genetic make-up and the environment appear to play a part.

Gluten are found in wheat, barley, rye, kamut and oats. So apart from bread many other products may contain gluten such as pizza, pasta and not to forget beer, as barley plays an important role in the production of beer. There is also another aspect. Even if a certain cereal does not contain gluten (corn of soy for instance) one has to be careful about cross-contamination. Gluten-free cereals might get contaminated with wheat or other gluten containing cereals during transport, storage and milling. So it is absolutely necessary to know that the source of gluten-free ingredients is completely trustworthy (e.g. producers of improvers; do they have separate facilities to mix the products?) . Same thing applies to the bakery i.e. gluten free products have to be produced in a separate facility and can under no circumstances be produced in a bakery that also produces normal wheat bread.

Consumers with an intolerance to the wheat protein gliadin or suffer from sensitivity to gluten, are estimated at up to 5 % of the EU population. Besides the people who suffer from coeliac disease, an increasing number of consumers choose gluten free products because they are perceived as “more healthy”. However being on a gluten free diet without medical urgency and good guidance can harm your health. A gluten-free diet is fashionable but one-sided because gluten contain lots of healthy nutrients and fibres which are important. The idea that bread an gluten are unhealthy is coming from the United States but there is no scientific evidence to support such a claim.

Gluten is a composite of two proteins called gliadin and glutenin. These exist together with starch and endosperm of wheat and other crops of the Triticeae family (which includes other types of cereals such as barley and rye). Gluten is an insoluble protein that is best recognised for giving kneaded dough its elasticity and for adding chewiness to finished baked goods. It also helps trap gas bubbles resulting from the fermentation of sugars in yeast-raised baked goods, causing the dough to rise. During baking, gluten coagulates, stabilizing the dough mixture and contributing to overall crumb structure and volume.

In baked goods, gluten is a key functional component. It provides extensibility, mixing tolerance, and gas-holding ability to the dough, all of which influence product structure and volume. Gluten contains the protein fractions glutenin and gliadin. The former is a rough, rubbery mass when fully hydrated, while gliadin produces a viscous, fluid mass on hydration. Gluten, therefore, exhibits cohesive, elastic and viscous properties that combine the extremes of the two components. The gluten matrix is a major determinant of the properties of dough (extensibility, resistance to stretch, mixing tolerance, gas holding ability), enclosing the starch granules and fibre fragments. A significant challenge to eliminating gluten from a traditional bread dough system is the change from a plastic dough to a liquid batter. Resulting products are very different in appearance, texture, and eating quality.

Approaches to producing gluten-free baked goods revolve around the use of certain cereal grains like rice and corn in combination with speciality starches and hydrocolloids. These combinations of ingredients can help recover some of the dough characteristics lost when omitting the gluten-containing materials.

Alternative flours that could be incorporated in a gluten-free formulation include rice, sorghum, bean, soy, potato, amaranth, quinoa, and teff. Starch sources include tapioca, potato, corn, and arrowroot. Other binding ingredients such as egg or soy protein may help to form the structure of the gluten-free product. As compared to traditional baked goods, gluten-free products tend to be higher in cost because of the use of speciality ingredients, and have a shorter shelf life.

How to determine the quality of bread

The wheat protein gluten is the origin of the excellent elastic properties of wheat dough responsible for its good baking properties. Gluten forms a network which has high extensional viscosity and is strain hardening thus stabilizing and trapping air bubbles to give the desired porous structure typical of white bread. There are prolamine proteins corresponding to wheat gluten in all cereals, however, few of them have the required properties for baking, i.e. they especially lack the extensional rheological properties necessary for foam stabilization under normal baking conditions. There is still desire to bake gluten free bread both due to the demand from gluten intolerant Europeans and due to high wheat prices in e.g. Africa. Gluten-free products are necessary for those suffering from coeliac disease caused by wheat gluten, which is a well-recognized problem in Western Europe and USA where about 1 % of the population is suffering from it.

The foam formation during baking involves high extension at low extension rates. The relevant rheological methods for predicting foam stability of dough must involve extension. The microstructure of the flour based dough revealed that the protein was trapped in its physiological structure and the amount insufficient. A protein content of 15 - 20 % was needed to form a good bread structure, and foam formation was facilitated by addition of plasticizing components and hydrocolloids such as beta-glucan rich bran and modified cellulose.

Obviously eating it is the first and most important method to access the quality of bread. But next to that – especially if one has to compare two different loaves – there are some parameters which are useful to quantify the quality of bread in an objective manner. Some of the instruments used for this purpose are:

Additionally one can also evaluate nutritional aspects such as protein content, fibre content etc.

Development of gluten free products

The specific contribution of gluten to texture relates to the strength of the dough, the size and uniformity of the air cells within the dough, and the presence of a heterogeneous matrix within the dough. A weaker dough yields larger and less uniformly sized air cells. Weaker dough also exhibits greater heterogeneity and yields a longer, chewy texture. Stronger dough has smaller and more uniformly sized air cells and exhibits a less heterogeneous appearance. The strength of the gluten replacement system is critical to mimic of the targeted bread product.

The physical space that the gluten occupies within the dough in a whole wheat bread also requires compensating adjustments. An effective replacement method must ensure that the volume and weight contributed by the gluten protein are replaced with a gluten-free alternative ingredient.

The gluten-replacing ingredient must help with water management in a similar manner. Water must be controlled in order to postpone the rate of staling and to prevent mould. The shelf life of a gluten-free product tends to be equal to or less than that of a typical wheat-based product, depending on what the product is and how it is stored. The strategic application of sugars helps to bind water and manage such changes during storage.

The flavours and textures of gluten-free ingredients generally do not result in a product that would be considered acceptable when compared with a refined-flour product such as commercial white pan bread as it is on sale in the UK or the Netherlands. However, the likelihood of success in mimicking the flavours and textures of whole wheat, whole grain, or brown breads is far greater

Currently, many gluten-free products available on the market are of low quality, exhibiting poor mouth feel and flavour. Such problems are rarely encountered during the manufacture of gluten-free biscuits, as the development of a gluten network in biscuit and cookie dough is generally minimal and undesirable; the texture of baked biscuits is primarily attributable to starch gelatinisation and super-cooled sugar rather than a protein/starch structure.

To replace wheat flour, one can choose from a number of alternative ingredients. However the whole issue boils down to two questions:

How to replace wheat flour isn’t an easy question. One can choose from a number of alternative ingredients. However through a method of “trial and error” one has to establish the most suitable recipe. What follows is a list of ingredients one can choose from.

It also has been reported in the literature (Network formation of gluten-free bread with application of transglutaminase – Cereal Chemistry 83:28-36) that transglutaminase can help to form a protein network which subsequently will improve the structure of the gluten-free bread. The efficiency of the enzyme is dependent both on the protein source and the level of enzyme concentration

I understand that everyone hopes to find on this page a good reliable recipe for gluten-free bread. I am however reluctant to give one because developing gluten-free products is not an easy thing to do and all ingredients as well as the quantity used, should be studied and scrutinised carefully. Hence the following recipe might or might not work and can only be a starting point for further development. If you need assistance to develop gluten free products, we gladly advise you for an acceptable fee.

ingredient

quantity

water

2,800 kg

white rice flour

1,350 kg

egg whites

1,150 kg

tapioca starch

1,000 kg

sorghum flour

0,750 kg

brown rice flour

0,700 kg

olive oil

0,250 kg

sugar

0,240 kg

yeast

0,150 kg

psyllium fibre

0,070 kg

salt

0,040 kg

guar gum

0,030 kg

xanthan gum

0,020 kg

total

8,550 kg

Psyllium fibre is derived from the husks of seeds of Plantago ovata but can be replaced by other types of fibres such as apple, pea etc.



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Noël Haegens

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