Cellulose food gums: baking quality into gluten-free products.
As the number of people diagnosed with gluten intolerance, also known as celiac disease, is rising sharply around the world, and consumers choose to reduce their intake of wheat-based products, the food industry is developing gluten-free baked goods to meet the needs of this demand. Now, as a result of improved technology, these products are competing with their wheat-based counterparts in terms of consumer appeal and quality.
Interestingly, 10 years ago, gluten-free bread was sold in a pharmacy and out of a tin box; such products were used to address important dietary restrictions to avoid celiac disease. Now, thanks to the progress of food companies who have dedicated themselves to the manufacture of high quality gluten-free ingredients and products, people affected by celiac disease can currently enjoy a variety of bakery products, ranging from muffins, bread, cookies and pizzas. Today, supermarkets have designated sections for gluten-free shoppers and it is likely that, during the next 10 years, we will see "gluten-free" as a choice on food menus in restaurants--in much the same way that vegetarian and meat-free choices are available.
In food production, gluten is a protein that plays a significant role from the early stages of dough processing all the way through to the baking of the finished product. Gluten-free bakery products could, potentially, end up being more dense and have a much less tender texture as a result of its absence. METHOCEL food gums offer a solution to gluten replacement. They are allergen-free and a good source of dietary fibre. In addition, they offer surprisingly unique benefits that mimic the gluten protein and can address the food formulation issues that developers face when processing dough products without gluten, such as aiding with dough structure and development. METHOCEL technology is based on cellulose derived from natural sources; it undergoes a proprietary procedure that enables its unique emulsifying and thermal gelling characteristics, which support the replacement of gluten throughout the bakery process.
It All Starts with the Dough
Anyone who has ever tried to bake a gluten-free product knows that the handling of the dough is, indeed, "a sticky problem." The issue is especially important when a bread dough is needed: without gluten, elasticity cannot be developed within the dough and the kneading process remains ineffective. During the kneading of a traditional wheat-based bread dough, the gluten lengthens and develops a film network that provides both strength and elasticity, as well as the ability to trap water and gases, which ensures moistness and enables the dough to rise during baking (Figure 1).
Hydrocolloids, more commonly known as food gums, can also affect the rheological behaviour of dough, as they mimic the viscoelastic properties of gluten and trap water. METHOCEL has the ability to hydrate quite quickly when used in dough or cake batter formulations and can trap water very effectively. Dough processing is a high shear procedure: METHOCEL, like gluten, is very process tolerant and resistant to this shear. As gluten-free batters are usually mixed quite intensely to develop and distribute ingredients, it is key to use hydrocolloids that will not be damaged by this high shear process. Moreover, it has been observed that the film-forming properties of METHOCEL act as a lubricant inside the batter and protect the other formulation ingredients from being damaged by mixing--particularly starch granules. This increased mixing tolerance will, to some extent, protect the dough from occasional "over-mixing accidents" and ensure optimal functionality of the ingredients in the latter stages of production. And, finally, cellulose gums are used widely in food products for their tensioactive properties. This tensioactivity, derived from METHOCEL's hydrophilic and hydrophobic properties, provides reduced surface tension between the water and air/ water/fat inside the dough. This provides the unique emulsifying properties that are necessary to mimic the gluten protein.
[FIGURE 1 OMITTED]
It is important to describe and understand this emulsifying property better. When oil and water or air are combined in foods, an interface is created inside the food product. For example, an air and water interface is created in a mousse or whipped topping and an oil and water interface is seen when we create an emulsion or dressing. Typically, oil and water or air do not want to be in contact with each other and, to mix effectively, they require an emulsifying agent that reduces the tension created between these two interfaces. Gluten acts as such an agent because it is "amphiphilic" and has both a hydrophobic and hydrophilic moiety on its surface. METHOCEL also possesses this characteristic and will thus migrate to the interface. So, during the mixing of the dough, when air becomes incorporated into the dough matrix, gluten helps to ensure that the air stays trapped by emulsifying the surface; this keeps the gases in place and ensures that the dough rises properly during baking. In gluten free dough, however, there is no gluten to trap the gases. So, METHOCEL is used as a gluten replacement and wraps itself around the air bubbles and keeps the gases trapped for the baking cycle. Later, during proofing and baking, proper nucleation of the gas cells will be induced in the dough structure by using a bicarbonate or yeast leavening agent.
A Key Role During Baking
It was described earlier that, in the absence of gluten, gases produced by yeast during proofing or chemical leavening--needed to support the volume expansion caused by increased temperature in the oven--are not trapped in gluten's elastic network. There are other food gums that can trap air as a result of thickening and viscosity; but, when heated, these gums typically lose their viscosity. This is the case with guar gum, cellulose gum and, to a lesser extent, xanthan gum. This loss of viscosity weakens the dough structure and, especially in large size products or free-bake products, will not enable the proper raising of the foodstuff. The result is a bakery product that is very dense or compact, the starch cooking time becomes very long and difficult, and the resulting texture of the product is often wet and gluey. Figure 2 shows three different gluten-free breads. The control (gluten-free with no food gum) is compared with a gluten-free/guar food gum and a gluten-free/ METHOCEL food gum loaf. The difference in volume and expansion of the bakery product can easily be seen between the control and guar gluten-free breads versus the bread made with METHOCEL. This is the result of the loss of gases too early during the baking process.
It is important that the food gum does not lose viscosity too quickly when heated, or gases will escape. Most food gums dehydrate and lose viscosity when heated but METHOCEL actually increases in viscoelastic performance when heated and forms a gel network. A gel is defined as having an infinite viscosity, and the METHOCEL gel networks can best trap gases and water when heated during the baking process; the loss of viscosity is reduced, which improves the dough's ability to both rise and retain moisture, giving optimal texture properties. The gel traps water and gases during the baking cycle but will then revert back to normal when removed from the heat. This technology allows you to select the thermal gelation temperature that is most suitable for your product, to provide structure or trap water and gases, as well as select the required degree of gel strength, which ranges from
uid gel type to slight to firm, brittle and cuttable gels. Figure 3 shows various degrees of gel formation. A uid gel can be seen at the bottom. This uid gel will trap water but has a pourable texture. If needed, you can also achieve a firm gel texture, which traps water in a more rigid gel network and provides a firm texture, as pictured in A.
[FIGURE 2 OMITTED]
[FIGURE 3 OMITTED]
[FIGURE 4 OMITTED]
For gluten-free dough, METHOCEL's thermal gelation property means the creation of a viscoelastic layer around the gas cells that will not only trap them inside the product, but will also enable their expansion. Of course, appropriate selection of the gum type is critical, and this selection depends on the other ingredients and is adjusted to each formulation. Although METHOCEL gels do reverse when removed from the baking cycle, this does not mean that the bakery products collapse. as the starch structure will be well set by then.
It is well known that gums, because of their hydrophilic character, can control the swelling and gelatinization of starch granules. Whereas carrageenans, alginates and xanthan gums decrease the temperature of starch gelatinization, optimum levels of METHOCEL can delay its initiation. This may be a result of MEfHOCEL molecules wrapping themselves around the starch granules (tensioactivity) and the subsequent release of free water when the gum forms a gel; the free water ensures the optimum cooking of the starch. For a gluten-free dough, this will mean delayed setting of the structure and optimum volume expansion (Figure 4).
Softness and Shelf-Life
Once the structure a of the gluten-free products has been set by baking, they are packed and stored. It is important that these products can hold onto their freshness; they are not generally sold at the "local bakery" so maintaining quality and freshness is extremely important. Typically, gluten aids in retaining freshness as it helps to delay starch retrogradation; however, in the absence of gluten, starch undergoes a rapid retrogradation and the staling of gluten-free products can occur quite quickly. Several options exist to reduce this phenomenon, including the incorporation of food gums, fat and enzymes in the formulation. The ability of METHOCEL to trap water, as described in the first mixing stage, will slow down the dehydration rate of gluten-free products and enhance their shelf-life and freshness.
In summary, the increasing consumer demand for gluten-free products is fortunately being met with improvements in food technology that will support both their quality and freshness as they make their way to becoming more mainstream among the growing selection of choices for healthier foods. METHOCEL products have been used in the food industry for the past 40 years. Dow's Food & Nutrition group is a leader in the formulation and product knowledge of this cellulose food gum. Our team offers the gluten-free customer an understanding of these dynamic surface-active food gums and assistance in replacing gluten in dough while maintaining proper rheology, gas entrapment and dough conditioning. Dow's team is able to cut development times and increase speed to market, while enhancing finished product quality and production reliability. We are focused on new solutions that help gluten-free producers address the health trends and needs of the gluten/allergen-free market. Bon Appetit!
The Gluten-Free Market
There are three main gluten-free consumer categories:
1. Gluten-intolerant people (celiac disease) suffer from an inflammation of the small intestine when eating gluten-containing foods. The disease can take a great variety of forms, ranging from typical enteropathy to skin rashes and emotional disorders. Gluten intolerance is also the first cause of nutrient malabsorption in children. One in 300 people in Europe and USA are affected by gluten intolerance.
2 Gluten reducers and/or avoiders reduce or eliminate the gluten present in their food and may suffer from mild intolerance to gluten, "allergies" or irritable bowel syndrome. They may also be members of a family wherein one or more persons is affected by celiac disease.
3. Phenylketonuriacs suffer from a life-threatening disease that manifests itself as an impossibility to break down the proteins contained in their diets.
For more information
Global Food & Nutrition Marketing Manager
Dow Wolff Cellulosics
Dow Europe GmbH
Tel. +41 44 728 2035
METHOCEL[TM] is a registered trade mark of Dow Wolff Cellulosic
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|Title Annotation:||free-from nutrition|
|Publication:||Nutraceutical Business & Technology|
|Date:||Sep 1, 2008|
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