Physiochemical Processing of Bread and Gluten Essay

Introduction

It is important to note that bread is among the most common forms of carbohydrate foods around the globe. Bread is a product created from the mixing of ingredients and enabling fermentation by yeast microorganisms, which process and ferment sugar in flour. However, some individuals suffer from celiac disease, an autoimmune disorder where consumed gluten triggers the immune system to attack the intestinal lining cells. Therefore, understanding the process of bread making through fermentation and altering it to make it gluten-free can help people to be able to safely consume bread without causing a celiac response.

Part One: Physiochemical Changes During Bread Processing

It should be noted that bread is a result of yeast’s interaction with the mix of ingredients provided for it to grow. Essentially, bread is “the product of baking a mixture of flour, water, salt, yeast, and other ingredients” (Baking Industry Research Trust, 2021, para. 1). The main source of food for the microorganisms is flour itself, which is derived from wheat, and it is a combination of starchy carbohydrates as well as some protein. The latter is mostly comprised of glutenin and gliadin proteins, which become gluten under the mixture with water and kneading (Exploratorium, 2021). It is stated that the “technical definition describes the sourdough as a mixture of flour and water, spontaneously fermented by lactic acid bacteria and yeasts, and having acidification and leavening capacities” (Arora et al., 2021, p. 71). In other words, flour is mixed with ingredients to allow yeast and bacteria to ferment the starches, which produces metabolites, and the baking removes both microorganisms and provides the desired physical properties.

The first step in the process of making the bread is mixing to ensure even distribution. The core ingredients in the mixture are flour, water, salt, and yeast. The given initial mixing additionally allows the development of gluten from glutenin and gliadin proteins present in flour (Baking Industry Research Trust, 2021). It should be noted that overmixing “produces a dough that is very extensible with reduced elastic properties” (Baking Industry Research Trust, 2021, para. 8). However, if the dough is undermixed, the rising will be done to a smaller extent, and there will be unmixed patches leading to poor internal appearance. Therefore, yeast is provided with an optimal environment to induce its next phase, which is primarily driven by the microorganisms.

The second step is fermentation, where yeast cells consume flour and sugar through the alcoholic fermentation pathway. During this process, glucose is used to create ethanol and carbon dioxide as byproducts. Since the mixture of dough is mostly devoid of oxygen, yeast cells are unable to process glucose through a normal respiration pathway, which usually creates carbon dioxide and water (Maicas, 2020). Alcoholic fermentation is triggered due to the lack of oxygen in the dough, and thus, the rising of the mixture occurs because the dense mass is expanded by sockets or cells holding the carbon dioxide (Baking Industry Research Trust, 2021). It is stated that the result is “thousands of tiny bubbles, each surrounded by a thin film of gluten from cells inside the dough piece” (Baking Industry Research Trust, 2021, para. 14). The sticky part of the dough is due to gluten forming networks that combine together and give the mixture its physical properties.

The third step is kneading, which is a rhythmic and repetitive stretching and folding of the dough. The process develops gluten further and releases excess gas formed during the fermentation. It is stated that “any large gas holes that may have formed during rising are released by kneading, and so a more even distribution of both gas bubbles and temperature also results” (Baking Industry Research Trust, 2021, para. 13). In other words, the mixture becomes more homogenous in its consistency and texture. It is important to note that the kneading duration, intensity, and approaches can differentially alter the consistency, viscosity, elasticity, and density of the final product. The same principle applies to the initial mixing phase, where kneading is additionally utilized to mix the ingredients properly before the first fermentation.

The fourth step is called second rising, which is the final enablement of fermentation. After a proper and intensive kneading, new bubbles of carbon dioxide are created by the yeast cells, which provide the bread with its porous structure. The lining of the holes is supported by gluten proteins (Baking Industry Research Trust, 2021). The dough is allowed to sit until it reaches the desired size, after which it is baked.

The fifth critical phase is baking, where the dough is treated at high temperatures in the oven to prepare the final product. It should be noted that the dough itself is heavy, unpalatable, and indigestible to a certain extent, and thus, baking makes it light, digestible, and flavorful (Baking Industry Research Trust, 2021). The temperature turns all of the carbon dioxide content into its gaseous form as well as evaporates alcohol. It is stated that “weight is lost by evaporation of moisture and alcohol from the crust and interior of the loaf” (Baking Industry Research Trust, 2021, para. 26). In addition, higher levels of heat kill the yeast cells and natural enzymes, such as amylase (Baking Industry Research Trust, 2021). The brown crust of the bread is created by the leftover sugar molecules, which sweeten the bread.

The external of the loaf reaches the highest temperatures before the internal parts. It is stated that “the gluten strands surrounding the individual gas cells are transformed into the semi-rigid structure commonly associated with bread crumb strength” (Baking Industry Research Trust, 2021, para. 23). In other words, the loaf gains all of its desired physical properties during the baking, and the temperature removes alcohol and yeast cells.

The final stage of the process of making bread is cooling. It is critical to allow the loaf to cool in order to enable the full evaporation of the steam. Without it, the bread will be loose and moist enough, which might make the packaging process problematic since the structure can be easily damaged (Baking Industry Research Trust, 2021). It is stated that “a moist substance like bread loses heat through the evaporation of water from its surface. The rate of evaporation is affected by air temperature and the movement of cool air around the loaf” (Baking Industry Research Trust, 2021, para. 30). A specific cooling area can be used with lower temperatures and moving air to facilitate the process of vapor removal.

In conclusion, the usual bread processing involves six stages, which include mixing, fermentation, kneading, second fermentation, baking, and cooling. Throughout the process, the yeast cells are allowed to undergo the alcoholic fermentation pathway to consume the flour and produce the physical porousness of the bread as well as make it more digestible. The protein content of the flour is turned into gluten to enable the desired structure and texture. The baking process removes all yeasts and alcohol, and it makes the bread even more available for digestion.

Part Two: Changes for People with Celiac Disease

It is critical to note that individuals with celiac disease are sensitive to the gluten content of the bread. The condition can be defined as “a serious autoimmune disease that occurs in genetically predisposed people where the ingestion of gluten leads to damage in the small intestine” (Celiac Disease Foundation, 2021, para. 1). It affects approximately 1% of the total global population (Celiac Disease Foundation, 2021). The only available treatment for celiac disease is full and strict avoidance of gluten, which implies adherence to a gluten-free diet. Therefore, the changes that should occur in order to develop the product for individuals with the condition is making bread without gluten. Since the rising structure and dough’s elasticity are mostly provided by gluten, the protein alters the process of bread making. It is stated that “most of the research available to improve gluten-free (GF) bread is based on substituting or imitating the gluten network” (Bender and Schonlechner, 2020, p. 1). In other words, such bread is made by removing the protein from flour during the wheat processing phase.

There are two strategies to make bread for people with celiac disease, which are optimized ingredients or technological approaches. Firstly, in the case of optimization of ingredients, the complete removal of gluten content from the flour only leaves starches, which makes it impossible to make gluten-free bread. However, the structure provided by the protein can be replaced with hemicelluloses, such as arabinoxylans (Bender and Schonlechner, 2020). The latter can be used as a substitute supplemented with gluten-free flour to enable the bread-making process. It is essentially a dietary fiber, which is rigid and indigestible enough to support the carbohydrate network created by starches. Hydrocolloids can also be used as an additive, and it is a long chain of polysaccharides and proteins used to thicken the food product, stabilize, and help to retain water (Bender and Schonlechner, 2020). Other approaches can use different forms of proteins, fats, emulsifiers, or enzymes to ensure that a gluten-free bread resembles its desired properties.

The second strategy is centered around the technological approaches, where non-conventional baking technologies are utilized. For example, it is stated that “Ohmic heating resulted a promising approach to overcome bread quality issues while remaining time and energy-efficient” (Bender and Schonlechner, 2020, p. 1). In other words, it uses an electrical current to generate heat due to resistance. Although it can only be applied to food with a particular degree of viscosity, its advantage is the ability to inactivate yeast cells through electric and thermal damage (Bender and Schonlechner, 2020). By using this non-conventional baking technique, gluten-free bread can be prepared from flour devoid of gluten.

In sum, celiac disease can only be treated by a full avoidance of gluten protein in bread. Since bread processing relies on gluten to support its unique physical properties as well as the elastics structure of its starch complexes, a substitute is needed. The latter constitutes the first strategy of gluten-free bread making. It is important to note that another strategy is to use innovative baking methods, such as Ohmic heating, to be able to bake gluten-free doughs.

Conclusion

In conclusion, bread is commonly made in six stages, which involve mixing of the ingredients, fermentation, kneading, second fermentation, baking, and cooling. The process provides yeast microorganisms with an optimal environment to induce alcoholic fermentation, which turns starches into alcohol and carbon dioxide. Gluten is a protein created from kneading and mixing, and it is responsible for the structural properties of the bread. For people with celiac disease, gluten must be removed. Components, such as hydrocolloids or arabinoxylans, provide the structural support for the bread without the use of gluten. In addition, ohmic heating is an option for baking gluten-free doughs.

Reference List

Arora, K. et al. (2021) ‘Thirty years of knowledge on sourdough fermentation: a systematic review’, Trends in Food Science & Technology, 108, pp. 71-83. Web.

Baking Industry Research Trust. (2021) Science of bread making. Web.

Bender, D., and Schonlechner, R. (2020) ‘Innovative approaches towards improved gluten-free bread properties’, Journal of Cereal Science, 91, pp. 1-8. Web.

Celiac Disease Foundation. (2021) What is celiac disease? Web.

Exploratorium. (2021) Bread science 101. Web.

Maicas, S. (2020) ‘The role of yeasts in fermentation processes’, Microorganisms, 8(8), pp. 1-8. Web.