The Science Behind Bread Production

Cereal grains are the primary crops that have enabled the sustenance of human life. Currently, cereal grains constitute the primary source of energy for the majority of the global population. Wheat bread represents one of the most commonly consumed cereal items (Alkurd et al., 2020). The significance of wheat mostly arises from its seeds, which may be milled into flour, semolina, and other products that constitute fundamental ingredients for bread, bakery products, and pasta, thereby serving as a principal source of nutrition for a substantial portion of the global population (Šramková et al., 2009). Bread has been the most significant staple food source for humanity since ancient times. Recent investigations indicate that baked bread was incorporated into the diet of hunter-gatherers no less than 30000 years ago (Valavanidis, 2018).  

Bread has been produced since 10,000 B.C. and it is identified as "the essence of life." Before agriculture began to flourish at the beginning of the Neolithic era, the primary component in bread was seeds. Some of the oldest surviving papyriin from Egypt have instructions on how to make bread, a form like modern bread. It was also stated there that the workmen's inadequate access to bread was the reason for the delay in the construction of the pyramids (Kourkouta et al., 2017). Various nations exhibit distinct approaches to bread preparation, encompassing both unleavened and leavened varieties. Natural leavening sponge is generated from residues in dough containers, retained dough from prior batches, or baker's yeast combined with flour, water, and leavening agents. Sourdough fermentation is often preferred due to its flavor and sensorial characteristics (Becila et al., 2026).

Bread differs in form, composition, flavor, preparation techniques, state of origin, and nomenclature, influenced by regional culture. In the basin of the Mediterranean, wheat is frequently the primary cereal utilized in bread making, although barley or a combination of both is also popular (Becila et al., 2026). In times of severe hunger, it is considered to be the most affordable, nutritious, and basic supplementary food available (Kourkouta et al., 2017). 

Wheat Grain Morphology

Wheat grains are generally oval-shaped, although different types of wheat have grains that range from almost spherical to long, narrow and flattened shapes. The wheat grain in Figure 1 comprises 2-3% germ, 13-17% bran, and 80-85% mealy endosperm, all expressed on a dry matter basis (Šramková et al., 2009).

Figure 1: Wheat Grain Structure (AgCommunicators, n.d.).

The outer layers of wheat grain, known as the bran, consist of many layers that shield the core of the grain. Bran is considered to be rich in B vitamins and minerals. It comprises water-insoluble fibre (approximately 53% of the bran), which protects the grain and endosperm material. The chemical composition of wheat bran fiber is mostly cellulose and pentosans, which are polymers derived from xylose and arabinose, strongly linked with proteins. The fused pericarp and seed coat surround the endosperm. The outer endosperm, known as the aleurone layer, is abundant in proteins and enzymes that are crucial for germination. The inner endosperm, known as nutritious or starchy endosperm, has lipids (1.5%) and proteins (13%), including albumins, globulins, and the principal proteins of the gluten complex: glutenins and gliadins, which are responsible for forming gluten during dough preparation. The germ is located at one end of the grain. It consists of proteins (25%) and lipids (8-13%). It is high in minerals and a source of Vitamin E (Šramková et al., 2009).

Wheat Grain Protein Composition 

The protein concentration in wheat grains may differ between 10% and 18% of the total dry weight. Wheat proteins comprise albumins, globulins, gliadins, and glutenins, with albumins being the smallest in size, followed by globulins. Gliadins and glutenins are complicated high-molecular-weight proteins. In cereals, albumins and globulins are primarily concentrated in the seed coats, with lower levels in the endosperm. The albumin and globulin fractions constitute approximately 25% of total grain proteins, whereas gliadins and glutenins, which are storage proteins, account for approximately 75% of the overall protein composition (Šramková et al., 2009).

Gluten Network Structure

Gluten accounts for 80-85% of the total wheat flour protein, comprising monomeric gliadins and polymeric glutenin proteins. Characterizing gluten is challenging because it encompasses a complex mixture of homologous proteins that vary significantly in molecular weight and charge. These gluten proteins influence the viscoelastic properties of wheat dough by forming a network when hydrated and mixed with flour. They include glutenin, which is polymeric, and gliadin, which is monomeric. The structural differences between glutenin and gliadin confer distinct functionalities during dough production. Generally, glutenin proteins create the polymeric network that ensures dough cohesiveness and elasticity, while gliadins act as plasticizers, affecting viscosity and extensibility (Ooms & Delcour, 2019).

Figure 2: Structural Schematic of Gluten Proteins in Dough (a) and Gluten (b) Network (Feng et al., 2020).

Different reactions and interactions are vital for forming a gluten network during dough mixing (Figure 2). Intermolecular disulfide (SS) bonds between glutenin polymers are key. Other covalent bonds, like isopeptide bonds and dityrosine linkages, have been suggested, but some researchers argue their contribution is negligible. At the same time, noncovalent interactions are also important; they significantly influence gluten properties due to their abundance and ability to exchange under stress. 

Gliadin and glutenin from various flours differ in hydrogen bonding, affecting interaction rates and mixing times for full dough development. Hydrophobic bonds also contribute to the gluten network (Ooms & Delcour, 2019).

Standards for Wheat and Flour Quality

The technological quality of wheat encompasses several characteristics of the kernel and flour that are crucial for the production of diverse baked goods, including bread, cookies, and crackers. It is widely recognized that both the quantity and quality of protein affect bread manufacturing. The amount of proteins in wheat grain is primarily dictated by genetic factors, water availability, and temperature throughout growth. The gliadin/glutenin ratio is the primary determinant. The quality of bread baking is influenced by the dough's physical characteristics, flour's ability to absorb water, bread volume, and the coloration of the crumb and crust (Osella et al., 2008).

Bread Types

Bread is a fermented confectionary item created mostly from wheat flour, water, yeast, and salt through a sequence of operations that include combining, kneading, proofing, shaping, and baking. Some varieties of bread are produced using a chemical leavening agent, such as baking soda, instead of yeast, while others are made without any leavening agent, resulting in a flat appearance. Furthermore, several kinds of bread types, differing in size, shape, flavor, and texture, are produced from various ingredients and processed under distinct conditions throughout different regions (Das et al, 2023).

There exists a wide range of bread types globally, each exhibiting distinct features, including those manufactured from various grains, unique ingredients, and made using an extensive number of procedures, resulting in multiple shapes and sizes.

Generally, bread can be categorized into three primary types, as shown in Figure 3.

Figure 3: Bread Types  (Mumpi Ghose, 2020).

Yeast Breads:

These breads are leavened by yeasts and possess a medium to high rise or volume. The gases produced during yeast fermentation become trapped in the dough, resulting in a sponge-like shape during baking, characterized by air cells surrounded by walls containing starch granules incorporated into a gluten matrix.

Flat Breads:

Flatbreads can be either yeast-leavened or unleavened and possess a lower specific volume compared to pan bread. In the preparation, batters or kneaded dough are utilized, allowing for simple mixing and rapid cooking. Pita and Lebanese wrapper breads represent flatbreads; they are produced from yeasted dough that is flattened to a higher level before baking (Das et al, 2023). 

Quick Breads:

Quick breads typically incorporate baking soda and/or baking powder to enable leavening. Quick breads encompass rapid loaves like cornbread and banana bread, as well as muffins and biscuits (Das et al, 2023). 

Factors Enhancing the Gluten Network  

Various methods have been employed to improve the gluten network structure and, consequently, its functionality during the preparation of wheat flour dough. The functionality of gluten protein is heavily influenced by the specific dough formulation, as water and other common dough ingredients, such as salt, serve a crucial role in gluten network development. For instance, mixing and sheeting influence the level of gluten development. Moreover, various enhancing agents are frequently utilized in the baking sector. They provide greater monitoring of production processes, elevate product quality, and/or extend shelf life. For this purpose, redox agents and enzymes are extensively used to modify the development of the gluten network (Ooms & Delcour, 2019).

Oxidizing agents may be added to flour to boost its natural maturation, sometimes referred to as 'flour bleaching.' Benzoyl peroxide is one of the most frequently applied oxidizing agents for bleaching purposes. Chlorine gas can be utilized for this reason in order to achieve remarkable cake-making features, as its application in cake formulations tends to prevent collapse post-baking. When mixing the dough, flour particles are sufficiently moisturized and shredded to the point that they do not remain as separate units. Resulting in the formation of a constant network (Figure 4). 

Figure 4: Gluten Network Development During Dough Formation (Su et al., 2026).

Moreover, the mechanical behavior of dough is heavily influenced by the levels of water and salt added. The gluten network is also impacted by yeast metabolites produced during fermentation, such as ethanol, succinic acid, and glycerol. Furthermore, it has been confirmed that substances like glutathione, which yeast releases during cell death, are important.

However, the inclusion of sugar, for instance, has been linked to diminished consistency in bread dough, elevated stickiness, and enhanced elasticity. This has conventionally been associated with sugar's strong attraction to water, resulting in less water availability for hydrating gluten and starch.  Fat substances have been reported to lubricate gluten proteins and restrict their water absorption during pastry preparation.

In general, dough formation occurs in two stages: a hydration stage and an energy input stage during kneading. Followed by depolymerization and (re)polymerization reactions. Mixing intensity and energy are essential elements that significantly influence the attributes of the finished product. Both must exceed a minimal critical level to successfully create the dough, with the level varied according to the type of flour and mixer applied.

Enzymes can also offer a 'clean-label' substitute to chemical agents since they are entirely denatured during baking and do not require labeling. For example, oxidoreductases in dough preparation facilitate the direct or indirect crosslinking of gluten proteins via multiple covalent interactions, hence enhancing the dough structure.

Emulsifiers might be used in order to reinforce or stabilize dough systems by interacting with the gluten network. Diacetyl tartaric esters of monoglycerides and ethoxylated monoglycerides both have superior dough stabilization qualities (Ooms & Delcour, 2019).

Bread Flavour Characteristics

The flavor of bread derives from multiple sources, involving ingredients and processing techniques. Flour often possesses a mild flavor, primarily derived from the oils in the germ and bran components. Throughout the natural fermentation of bread production, new flavor compounds are generated within the dough. The intensity of these flavors and their distinct characteristics develop with prolonged fermentation. In addition, common flavor changes include the development of acid notes caused by microbial activity, which are noticeable in the bread crumb's flavor.

Flavor development is not primarily attributed to baker's yeast; wild yeasts and bacteria, particularly lactic acid bacteria present in the flour, also play a significant role. The most obvious influence on bread flavor comes from baking, where many flavor compounds undergo substantial changes. Including the formation of a dark, brown crust on the dough's surface results from Maillard browning, creating highly aromatic compounds. These compounds play a crucial role in flavor senses, with some opinions suggesting that up to 80% of bread flavor derives from the crust (Cauvain and Young, 2007).

According to a study by Žuljević and Sphao (2024), around 540 volatile compounds are the primary source of bread aroma. Alkaloids, aldehydes, esters, ketones, acids, pyrazines, and pyrrolines are the most abundant groups; furans, hydrocarbons, and lactones are also recognized. Despite this, the ultimate aroma of bread is predominantly influenced by a limited quantity of these. Various aspects, such as the type of flour and its extraction rate, other supplementary ingredients in the bread formulation, as well as the methods, conditions, duration of the fermentation process, and baking conditions, influence the final aroma of the bread.

Bread Preservation Technology 

Bread's shelf life is limited by physical-chemical, sensory, and microbiological alterations that occur in a dynamic system. Consequently, substantial economic losses occur for both consumers and producers (Rahman et al., 2022). Physicochemical and sensory alterations influence a decline in freshness, affecting acceptable texture and flavor, and result in the gradual hardening of the crumb. Microbiological deterioration caused by yeasts, bacteria, and molds includes observable mold proliferation, the undetectable synthesis of mycotoxins, and the development of off-flavors, as illustrated in Figure 5. Numerous efforts have been made to extend the shelf life of bread, minimize changes in organoleptic quality, and ensure safety (Bianchi et al., 2024). 

Figure 5: Origins of microbes in bread fermentation. Bacteria, yeast, and molds originate from packing, the atmosphere, and insects. Molds and bacteria with endospores are resistant to heat and might exist in bread after baking (Vermelho., 2024).

Physical techniques such as infrared, ultraviolet radiation, microwave heating, and ultra-high pressure treatments are employed to eliminate post-baking contaminants. Chemical preservatives, such as acetic acid, potassium acetate, sodium acetate, and others, are utilized in compliance with the limits established for food additives by the European Regulation (EC 1333/2008) (Bianchi et al.,2024).

For the past several years, the bakery field has endeavored to discover treatments that ensure bread safety and prolong shelf-life, focusing on economic and safety concerns, including the substitution of unhealthy chemical preservatives. Conversely, novel fields of study have been recently investigated. Alternative methods of bread preservation, including microbial fermentation, the use of plant and animal derivatives, nanofibers, and other innovative technologies, have shown promising results (Rahman et al., 2022).

Sourdough has lately emerged as a recognized method of food bio-preservation due to its low pH and elevated levels of lactic and acetic acid, which minimize deterioration from molds. Moreover, sourdough fermentation enhances the bioavailability of phenolic compounds and subsequently elevates the antioxidant capacity of the flour utilized. The sensory profile of bread is further influenced, exhibiting a richer flavor and greater sapidity than industrial bread manufactured with different leavening ingredients. In contrast, baker's yeast is favored for industrial applications due to its technological attributes, which streamline the production process and save costs. A viable technique to prolong the shelf-life of bread, without using preservatives, is the implementation of suitable modified atmosphere packaging (MAP) (Rahman et al., 2022).

Sourdough Bread

Sourdoughs can be characterized as stable ecosystems consisting of lactic acid bacteria (LAB) and yeasts utilized in the manufacture of baked products. Historically, sourdough served as a leavening agent; however, it is now widely utilized to enhance organoleptic properties and minimize the necessity for chemicals (Fernández et al., 2020).

Sourdough improves the quality of the resulting products and prolongs the shelf life of baked items. This increased shelf life is mainly due to lowering pH, which inhibits microbial growth, and to the breakdown of starch during lactic acid fermentation, resulting in a delayed staling. Utilization of sourdough allows the production of products with enhanced odor and sweetness, attributable to hydrolysis processes and chemicals formed during the Maillard reaction in the baking process (Fernández et al., 2020).

Sourdoughs have been found to reduce gluten content, which may be very appealing for reducing the risks of gluten contamination in gluten-free products. Sourdough can also enhance organoleptic characteristics of gluten-free products, consequently broadening the range of options available for individuals with celiac disease or wheat allergies (Fernández et al., 2020).

Sourdough bread has demonstrated efficacy as a method to enhance bread into a more appealing product, thus contributing to the sustainable growth of society. Breads made with sourdough decreased postprandial glycemia and blood insulin levels. The Glycaemic Index of whole bread leavened with yeast was 72.0%, but the utilization of sourdough reduced the Glycaemic Index to 53.7%. Certain Lactic Acid Bacteria (LAB) in sourdough possess the capability to synthesize exopolysaccharides that exhibit prebiotic, anticancer, and immunomodulatory activities.  Sourdoughs can be utilized to create nutritionally superior breads that incorporate additional cereals such as rye, oats, and barley. Measures are implemented to enhance the quality of these items. Quinoa bread and postponed mould formation by four days (Ognean, 2015).

The production of sourdough bread represents a conventional fermentation method. Historically, the initial method of bread production was natural leavening, utilizing endogenous lactic acid bacteria (LAB) and/or yeasts, which were inadvertently exploited from raw materials for centuries prior to the adoption of commercial yeast for leavening purposes. In sourdough production, a blend of cereal flour(s) and water is made, which is either fermented spontaneously and then backslopped for traditional sourdoughs or fermented in only one stage for a duration ranging from a few hours to several days for industrial sourdoughs. The produced sourdoughs are utilized as functional components of bread dough for the manufacture of leavened breads or as a substitute for baker’s yeast in traditional production (De Vuyst et al., 2023).

In general, sourdough is divided into four categories (I, II, III, and IV) according to the microbial inoculation and fermentation methods, Figure 6 represents sourdough types. Each form of sourdough demonstrates a distinct harmony between traditional techniques and accepted industry standards, providing diverse benefits regarding consistency, efficiency, and customization (Coronas et al., 2025).

Figure 6: Sourdough Preparation Methods (Coronas et al., 2025).

Conclusion 

Cereal grains are essential to the human diet and act as the primary form of energy for a substantial number of the global population, with wheat bread being one of the most extensively consumed cereal-based products. The quality and functionality of wheat dough are primarily determined by the gluten network, which can be improved by the use of oxidizing agents, enzymes, and emulsifiers. The flavor of bread arises from its ingredients, fermentation processes, and baking, with crust creation occurring due to Maillard browning reactions. Nevertheless, bread has a very short shelf life owing to physical, sensory, and microbiological alterations. To enhance preservation, physical treatments including infrared, ultraviolet, microwave, and ultra-high-pressure technologies, used in combination with chemical preservatives, are applied in order to reduce contamination. Sourdough fermentation is recognized as an efficient natural bio-preservation technology due to its low pH and high organic acid content, which prevent microbial development and prolong bread freshness. 

References

Alkurd, R., Takruri, H., Muwalla, M., & Arafat, T. (2020). The Nutritional Value, Energy and Nutrient Contents and Claims of Marketed Multi-grain Breads. Journal of Food and Nutrition Research, 8, 600–605. https://doi.org/10.12691/jfnr-8-10-9

Becila, F. Z., Dridi, L., Bouasla, A., Boussekine, R., & Bencharif, M. (2026). Bread and Bakery Products: Cultural Importance, Consumption, Purchase Patterns, and Household Waste During Ramadan in Constantine, Algeria. Sustainability, 18(1), 543. https://doi.org/10.3390/su18010543

Cauvain, S. P., & Young, L. S. (2007). Technology of breadmaking (2nd ed). Springer.

Coronas, R., Bianco, A., Sanna, A. M. L., Zara, G., & Budroni, M. (2025). Type I Sourdough Preservation Strategies and the Contribution of Microbial Biological Resource Centers to Biodiversity Protection: A Narrative Review. Foods, 14(15), 2624. https://doi.org/10.3390/foods14152624

Feng, W., Ma, S., & Wang, X. (2020). Quality deterioration and improvement of wheat gluten protein in frozen dough. ResearchGate, 3(1). https://doi.org/10.1016/j.gaost.2020.02.001

Kourkouta, L., Koukourikos, K., Iliadis, C., Ouzounakis, P., Monios, A., Tsaloglidou, & A. (2017). Bread and Health. Journal of Pharmacy and Pharmacology, 5(11). https://doi.org/10.17265/2328-2150/2017.11.005

Ooms, N., & Delcour, J. A. (2019). How to impact gluten protein network formation during wheat flour dough making. Current Opinion in Food Science, 25, 88–97. https://doi.org/10.1016/j.cofs.2019.04.001

Osella, C. A., Robutti, J., Sánchez, H. D., Borrás, F., & de la Torre, M. A. (2008). Dough Properties Related to Baking Quality Using Principal Component Analysis Análisis De Componentes Principales Entre Propiedades De Masa Y Productos Panificados. Ciencia y Tecnologia Alimentaria, 6(2), 95–100. https://doi.org/10.1080/11358120809487633

Šramková, Z., Gregová, E., & Šturdíka, E. (2009). Chemical composition and nutritional quality of wheat grain. 2(1), 115–138.

Su, F., Zou, Y., Zhang, Z., Tang, Z., Luo, H., Ye, F., & Zhao, G. (2026). Key Methodologies in Characterizing the Multi-Scale Structures of Gluten Proteins in Dough: A Comparative Review. Biomolecules, 16(3), 382. https://doi.org/10.3390/biom16030382

Valavanidis, A. (2018). Bread, Oldest Man-made Staple Food in Human Diet. Bread intake is integral to good health and whole grain cereals beneficial against chronic diseases. 1, 1–40.

Vermelho, A. B., Moreira, J. V., Junior, A., Silva, C. R. da, Cardoso, V. da S., & Akamine, I. (2024). Microbial Preservation and Contamination Control in the Baking Industry. ResearchGate, 5(231). https://doi.org/10.3390/fermentation10050231

Visual References

Cover image: [Photo of a freshly baked loaf of sourdough bread with a slice cut off displayed on a rustic wooden table with wheat stalks] (wahyu_t), Magnific. https://www.magnific.com/free-photo/freshly-baked-loaf-sourdough-bread-with-slice-cut-off-displayed-rustic-wooden-table-with-wheat-stalks_385493484.htm#fromView=search&page=1&position=29&uuid=950c3cce-a0bf-47c1-9a27-c703c3a65cb6&query=bread

 Figure 1: [Photo of a wheat grain structure] (AgCommunicators), GRDC  https://grdc.com.au/__data/assets/pdf_file/0027/227745/grdc-science-behind-dough-fa.pdf

Figure 2: Feng, W., Ma, S., & Wang, X. (2020). Quality deterioration and improvement of wheat gluten protein in frozen dough. ResearchGate, 3(1). https://doi.org/10.1016/j.gaost.2020.02.001

Figure 3: [Photo of various bread types] (Mumpi Ghose), Only Foods. https://www.onlyfoods.net/types-of-breads.html

Figure 4:  Su, F., Zou, Y., Zhang, Z., Tang, Z., Luo, H., Ye, F., & Zhao, G. (2026). Key Methodologies in Characterizing the Multi-Scale Structures of Gluten Proteins in Dough: A Comparative Review. Biomolecules, 16(3), 382. https://doi.org/10.3390/biom16030382

Figure 5: Vermelho, A. B., Moreira, J. V., Junior, A., Silva, C. R. da, Cardoso, V. da S., & Akamine, I. (2024). Microbial Preservation and Contamination Control in the Baking Industry. ResearchGate, 5(231). https://doi.org/10.3390/fermentation10050231

Figure 6: Coronas, R., Bianco, A., Sanna, A. M. L., Zara, G., & Budroni, M. (2025). Type I Sourdough Preservation Strategies and the Contribution of Microbial Biological Resource Centers to Biodiversity Protection: A Narrative Review. Foods, 14(15), 2624. https://doi.org/10.3390/foods14152624