A clean-label product can be referred to as food or ingredients that are more natural, organic, or not chemical-sounding and free of additives/preservatives. The bread industry and bakeries are going for clean-label products, adding only natural ingredients and additive-/preservative-free formulations but keeping the bread quality high. Thus, more research on natural ingredients can give the same attributes as traditional preservatives/additives to bread.
Bread is a centuries-old food and considered an essential dietary staple food worldwide. In addition, what is considered "bread" and the ingredients used change depending on the region. Bread is essential in the human diet and a good source of carbohydrates, dietary fiber, protein, minerals, and vitamins . Bread making has been changing over time, and there are differences in formulations, depending on the final product. Bread has four necessary ingredients: flour, yeast, water, and salt. The bread industry is usually looking for ways to improve its formulations . In the early twentieth century, the bread industry continued to develop, and the market changed with a more standardized process. Products and processes such as bleached white flour, flour enrichment, and chemicals were added to maintain consistency and improve quality . Bread formulations also have optional ingredients such as sugar (sweeteners in general), milk solids, fats, and conditioners . These ingredients affect the quality and taste of the bread, but other ingredients can improve quality, enhance dough handling, and extend the shelf life . Other ingredients such as oxidizing agents, reducing agents, buffers, enzymes, gluten proteins, and dough improvers/conditioners can improve dough rheology and extend the shelf life .
It is vital in bread making to establish the quality of flour and the final goal, considering its quality or industrial requirements to pick the right ingredients. The performance of bread made with wheat flour is directly affected by gluten proteins. Wheat flour is mainly composed of proteins, carbohydrates, and lipids . The gluten proteins interact with other components of the wheat flour. When mixed with the right amount of water, the gluten matrix develops, which allows the dough to hold gas during fermentation . The gluten proteins play a crucial role in baking by affecting the water absorption capacity, cohesivity, viscosity, and elasticity of the dough . Nevertheless, when the flour’s quality varies or is lower, dough improvers help standardize the final product and preserve quality. In addition, preservatives are sometimes added to the bread formulation to extend the shelf life. Fungal spoilage in bread is commonly known and has a substantial economic impact caused by the bread becoming unsuitable for human consumption due to food safety concerns .
Dough improvers and conditioners have been part of formulations in the bread industry for decades. Bread improvers help overcome deficiencies in the flour’s quality, improving loaf volume, crumb structure, shelf life, flavor, and color. The conditioners can be chemical redox agents and enzymes that may or may not be endogenous to the wheat flour, influencing the gluten network . The bread industry and formulations have changed in the past years due to more consumers being concerned about the food ingredients. Some bread improvers are perceived as unknown and harmful chemicals, and several may have controversial health issues. People want to know what the ingredients are and understand or feel familiar with them due to health concerns. A clean-label product can be referred to as food or ingredients that are more natural, organic, or not chemical-sounding and free of additives/preservatives . The bread industry and bakeries are going for clean-label products, adding only natural ingredients and additive-/preservative-free formulations but keeping the bread quality high . Thus, more research on natural ingredients can give the same attributes as traditional preservatives/additives to bread.
A good-quality gluten network is highly essential in bread making, directly affecting the ability to retain the yeast’s carbon dioxide and enhancing the dough’s properties. The gluten proteins’ quality can vary because of genetic, environmental, and post-harvest conditions. To maintain the same quality in bread making, the addition of additives/preservatives, dough conditioners, or strengtheners helps overcome the deficiencies in wheat quality . These dough strengtheners’ and preservatives’ primary functions are to increase . Some of the process improvements . Many chemical additives can be used in formulations and with different objectives.
Different strengtheners such as potassium bromate (PB), iodate, chlorine dioxide, chlorine, azodicarbonamide (ADA), ascorbic acid (AA), diacetyl tartaric acid esters of mono- and diglycerides (DATEM), sodium stearoyl lactylate (SSL), and peroxides, alter gluten proteins . Besides the effect they have on the overall dough rheology, to extend the shelf life, other chemical additives are used, too. Emulsifiers are a type of dough strengthener that improve the dough’s machinability, reduce resting time, and improve bread qualities such as volume, crust color, crumb whiteness, aroma, and flavor . Another benefit of emulsifiers is that they can improve the products’ shelf life. Chemical preservatives, like organic acids, are commonly used to prevent undesired microorganisms’ growth and extend the bakery products’ shelf life .
Consumers are looking for natural ingredients and no chemical additives due to health concerns. Most of the additives used nowadays do not have a health risk, but still, some consumers prefer the use of familiar names in the list of ingredients. Some of these additives/preservatives show health risks if used in specific ways or in excess. The use of azodicarbonamide (ADA) can impose a health risk during bread making if transformed into semicarbazide (SEM), which can be exceptionally high in the crust and have mutagenic and carcinogenic effects . During baking, ADA is converted to biurea, which is partly converted to SEM. This dough improver is prohibited in the European Union, but other countries such as Brazil, the United States, and Canada still permit it. Potassium bromate is also an additive considered to be carcinogenic. In rats, when given orally, it has been proven to induce renal cell tumors, mesotheliomas of the peritoneum, and follicular cell tumors of the thyroid . After baking, there can still be residual bromate in the bread crust with a usage of 9 ppm. The usage of potassium bromate is banned in some countries, while in others it is still legal, but its usage has reduced significantly . Ascorbic acid is considered an essential dietary nutrient and acts like an antioxidant. In studies with a high dosage of vitamin C, being 2 g per day, it is not likely to pose a risk or adverse effects in most individuals . Diacetyl tartaric acid ester of mono- and diglycerides (DATEM), another dough strengthener used in bread formulations, may have toxicity in rats, causing heart fibrosis and adrenal overgrowth .
Shoppers currently tend to purchase food products that they feel good about and believe are healthy, not only based on nutrition, but also based on being familiar with the ingredients . In Europe, 78% of shoppers consider the ingredients a vital factor when deciding on a product . In addition, some consumers can react adversely to products containing ingredients with unknown names, scientific names, or names that confuse them. Shoppers have become more skeptical, and processed and sometimes even dangerous . Younger-generation shoppers spend more time going through a product before deciding to buy it and are more likely to buy new, trendy, and attractive products . Other products that are shown to be organic or natural, environmentally friendly, socially sustainable, and innovative are also captivating buyers’ attention. Around 56% of consumers look for clean-label products because they are thought to be more natural and healthier . Different ingredients such as ascorbic acid, whey protein, and starch are more accepted in the ingredient list than guar gum, xantham gum, caseinate, and others . Consumers still seek healthier products that maintain freshness, quality, taste, texture, and consistency at an affordable price. The challenge for more industries is trying to look for clean-label reformulations that match the that consumers look for without lowering their quality. Product consistency is what most buyers look for in a product, and bakers seek formulations with better dough handling and shelf-life stability .
Clean-label trends have been continuously increasing in the past few years, and regulations depend on the region . Consumers are more concerned about having a healthier life, and in the United States, sales of natural bread and baking goods saw an overall growth of 11.3% in the last year up to March 2020 . In Europe, consumers are concerned about the ingredient list of a product, which has made the clean label a market success . There is no scientific definition of what is considered clean-label. However, the proposed definition is "Product not using artificial or synthetic chemicals and additives free, ingredient list easy to understand and common use, limited processing and by traditional techniques" .
In a broad sense, a clean-label product will have written or visual. A clean-label product, in the strict sense, will have a detailed ingredient list and a nutrition facts panel; a short, simple ingredient list with familiar ingredients; and no artificial or chemical-sounding ingredients . Even though consumers are looking for what they think are healthier products, such as those with clean-label formulations, the products must still maintain freshness, good quality, taste, texture, and consistency. In recent years, different industries have focused their research on ingredients that fit these characteristics and replace chemical additives/preservatives. Natural ingredients as dough strengtheners and preservatives have become a significant alternative for clean-label formulations .
In bread formulations, dough strengtheners improve the dough-handling process and hydration, increase the volume and/or crumb texture, reduce staling, and improve nutritional qualities . There are different chemical ingredients used for this purpose in the industry. Now more research is conducted to find other improving agents with more natural-sounding ingredients in clean-label formulations. Research has been conducted on the use of wheat flours and other flours and enzymes as alternatives .
Vital gluten is considered a highly valued functional protein and is the insoluble protein portion of wheat flour. In bakery formulations, vital wheat gluten is essential due to its features such as increasing functional protein content, water absorption, dough tolerance, and viscoelasticity, improving the volume and end product quality . The gluten protein network of wheat flour is divided into monomeric gliadins and polymeric glutenins. Most gliadins contain intramolecular disulfide (SS) bonds, and glutenin subunits also form intermolecular SS bonds that stabilize glutenin polymers. In the dough, the hydrated gliadins are responsible for dough extensibility and viscosity and are less cohesive than glutenins .
In contrast, hydrated glutenin is more responsible for dough strength and elasticity due to its cohesiveness and elasticity . A proper mixture of gliadins and glutenins is essential for the dough’s viscoelastic properties and quality for a starch–gluten matrix that can hold gas cells for better crumb and large loaf volumes of bread . High-quality, hard red spring wheat flour and vital gluten can substitute dough strengtheners as an option for clean-label formulations . The dough rheology and bread quality correlate with the molecular weight distribution of protein extracted from hard red spring wheat. Low-molecular-weight glutenin subunits (LMW-GS) strongly influence the bread-making quality . Different researchers have shown that vital gluten is essential in bakery applications used as a binding agent, contributing to dough strength, gas retention, and rise, while improving texture and flavor .
Amylases affect the gluten–starch matrix and, in the end, have been proven to affect the crumb structure, increase the level of fermentable sugars, and increasing the loaf volume, and heat-stable amylases help reduce staling in bread . Some researchers have investigated adding malt flour to whole-wheat bread instead of pure α-amylase due to the abundant amount of this compound . The effectiveness of malt flour depends on the flour quality. Malt flour can increase water absorption and extensibility, but it can also weaken the dough and decrease crumb quality.
Besides malt flour, there have been studies on adding other types of flour or using different yeast species and levels as strengtheners in bread formulations . A higher level of yeast can affect the specific loaf volume in some formulations. Lactobacillus species are used in clean-label breads to inhibit bacterial growth, and strains such as Lactobacillus amylovorus as a culture starter in wheat dough fermentation show good rheological properties in bread. In buckwheat sourdough bread, other fermenters, such as Gluconobacter albidus (TMW 2.1191) and Kozakia baliensis (NBRC 16680), also improved the bread sensory properties, with a high specific volume and softer crumb .
Preservatives are vital in the bread industry to maintain the freshness and quality of bread for extended periods. Mold growth is one of the most critical challenges in bread’s shelf life, Penicillium spp. and Aspergillus spp. being the most dominant species . In bakery products, shelf life is expected to be between 3 and 4 days when they are unpreserved, and spoilage after this period is commonly due to fungi . Food preservation helps reduce fungal spoilage and loss of quality; however, more consumers have a negative perspective toward food preservatives. More people look for natural antimicrobial preservatives instead of chemical-sounding ones, such as propionic and sorbic acids and salts . Some researchers have tested ingredients such as essential oils and fermentates to see whether they can have the same antimicrobial effect in bakery products as chemical preservatives. Other ways to preserve bread are using lactic acid ingredients to control the bread’s pH, being highly effective against pathogens .
Plants can combat pathogen infections by different compounds that can be separated into three categories: phytoanticipins, which are antimicrobial components; inducible performed compounds; and phytoalexins, which are inhibitory components synthesized when the plant feels attacked. All these compounds have a bio-preservative activity useful in the food industry. However, the one with more research are the antimicrobial components, where essential oils are the most significant group. There are around 3000 essential oils, but only 300 have commercial importance in the food, pharmaceutical, agronomic, and cosmetic industries. Essential oils’ antimicrobial activity is influenced by their composition, concentration, structure, and functional groups . In other research, clove bud (Syzygium aromaticum) and oregano (Origanum vulgare) essential oils have been used as antimicrobial preservatives to extend the shelf life of sliced bread. In this study, the authors used different sizes of emulsions of the essential oils in a methylcellulose film and then counted the yeasts and molds in sliced bread during the 15 days of storage at 25 ± 2 °C .
Intending to have a clean-label bread formulation are also studies changing the packaging type and using other types of additives in formulations (Figure 1). The packaging industries came out with strategies to extend the shelf life with modified atmosphere packaging (MAP) and active packaging . Modified atmosphere packaging is defined as the displacement of gases inside the package and their replacement by the desired mixture of gases or a natural result of the selected film type and product respiration . Active packaging consists of applying active agents directly to the packaging material instead of the food, enhancing food quality and safety .
Figure 1. Summary of packaging materials to extend bread’s shelf life.
The clean-label trend has become challenging for the baking industry and small bakeries. The food industry must respond to consumers’ demands for more natural ingredients without losing the bread’s taste, texture, and quality. Although there is no formal and standardized definition of a clean label, consumers still agree that the product should be healthy and have no chemical-sounding names in the ingredient list. Other research has focused on using different dough strengtheners and has shown that it is feasible to use other flour and wheat gluten. Dough properties such as water absorption, extensibility, strength, softer crumb, and loaf volume can be enhanced. Enzymes have shown a possible replacement for dough strengtheners such as hydrocolloids and emulsifiers. In the case of preservatives, there are investigations on fermenters and essential oils but with some challenges. As an option for extending bread shelf life, solutions as active packaging and modified active packaging are evaluated. The use of cinnamon and oregano essential oil has shown inhibition in microbial growth in bread. In conclusion, after proving an effective clean-label formulation, it is vital to assess the final product’s taste and texture and evaluate its replication in small- and large-scale bakeries. The future challenge is to keep investigating feasible and practical replacements of dough strengtheners and preservatives that bakers can use.