Bread Dough and Baker's Yeast: An Uplifting Synergy

Enhancement of fermentation traits in industrial Baker's yeast for low or high sugar environments

Saccharomyces cerevisiae SPC-SNU 70-1 is a commercial diploid baking yeast strain valued for its excellent bread-making qualities, including superior leavening capabilities and the production of flavor-enhancing volatile organic acids. Despite its benefits, this strain faces challenges in fermenting both lean (low-sugar) and sweet (high-sugar) doughs. To address these issues, we employed the CRISPR/Cas9 genome editing system to modify genes without leaving any genetic scars. For lean doughs, we enhanced the yeast's ability to utilize maltose over glucose by deleting a gene involved in glucose repression. For sweet doughs, we increased glycerol production by overexpressing glycerol biosynthetic genes and optimizing redox balance, thereby improving the tolerence to osmotic stress during fermentation. Additionally, the glycerol-overproducing strain demonstrated enhanced freeze tolerance, and bread made from this strain exhibited improved storage properties. This study demonstrates the feasibility and benefits of using engineered yeast strains, created solely by editing their own genes without introducing foreign genes, to enhance bread making.

Selenium-enriched yeast, a selenium supplement, improves the rheological properties and processability of dough: From the view of yeast metabolism and gluten alteration

This study investigated the effect mechanism of selenium (Se)-enriched yeast on the rheological properties of dough from the perspective of yeast metabolism and gluten alteration. As the yeast Se content increased, the gas production rate of Se-enriched yeast slowed down, and dough viscoelasticity decreased. The maximum creep of Se-enriched dough increased by 29%, while the final creep increased by 54%, resulting in a softer dough. Non-targeted metabolomics analyses showed that Se inhibited yeast energy metabolism and promoted the synthesis of stress-resistance related components. Glutathione, glycerol, and linoleic acid contributed to the rheological property changes of the dough. The fractions and molecular weight distribution of protein demonstrated that the increase in yeast Se content resulted in the depolymerization of gluten. The intermolecular interactions, fluorescence spectrum and disulfide bond analysis showed that the disruption of intermolecular disulfide bond induced by Se-enriched yeast metabolites played an important role in the depolymerization of gluten.

Honey as a Sugar Substitute in Gluten-Free Bread Production

In recent years, there has been a significant focus on enhancing the overall quality of gluten-free breads by incorporating natural and healthy compounds to meet consumer expectations regarding texture, flavor, and nutritional value. Considering the high glycemic index associated with gluten-free products, the use of honey, renowned for its numerous health benefits, may serve as an optimal alternative to sucrose. This study investigates the impact of substituting sucrose, either partially (50%) or entirely (100%), with five Sardinian honeys (commercial multifloral honey, cardoon, eucalyptus, and strawberry tree unifloral honeys, and eucalyptus honeydew honey), on the rheological properties of the doughs and the physico-chemical and technological properties of the resulting gluten-free breads. The results demonstrated that an optimal balance was achieved between the leavening and viscoelastic properties of the doughs and the physical and textural attributes of the resulting breads in gluten-free samples prepared with a partial substitution of cardoon and multifloral honeys. Conversely, the least favorable outcomes were observed in samples prepared with strawberry tree honey and eucalyptus honeydew honey at both substitution levels. Therefore, the different behavior observed among all honey-enriched gluten-free breads was likely attributable to the distinct botanical origins of honey rather than to the substitution percentages employed.

Moderate regulation of wheat B-starch ratio: Improvement of molecular structure, spatial conformation, aggregation behavior of reconstituted fermented doughs and its processing suitability

Aiming to investigate the changes and effects of different particle sizes of wheat A/B starch during dough fermentation, the present study reconstituted A/B starch fractions in ratios of 100:0, 75:25, 50:50, 25:75, and 0:100, further blended with gluten and subjected to slight (20 min), medium (30 min), and high (60 min) fermentation processes by yeasts. Results showed that fermentation gas production promoted gluten network extension, inducing starch granule exposure and dough surface roughness. Also, fermentation fractured protein intermolecular disulfide bonds and decreased α-helix and β-folded structure content, contributing to GMP, LPP, and SPP content decreases. Moreover, moderately increasing the B-starch ratio in the dough can improve gluten network stability, continuity, and air-holding capacity. The 25A-75B steam bread exhibited optimal processing suitability (better morphology, texture, and quality) due to its higher GMP and polymer protein content with lower free sulfhydryl and monomeric protein content. Further, conformational relationships indicated the key indicators influencing dough products' properties were free sulfhydryl content, GMP content, protein molecular weight distribution, and secondary structure. The obtained findings contributed to understanding the effect of wheat starch granule size distribution on dough processing behavior, and future targeted breeding for wheat cultivars with high B-starch content for improved fermentation pasta product qualities.

Technological and Nutritional Aspects of Bread Production: An Overview of Current Status and Future Challenges

Bakery products, especially bread, exist in many homes worldwide. One of the main reasons for its high consumption is that the main raw material is wheat, a cereal that can adapt to a wide variety of soils and climates. However, the nutritional quality of this raw material decreases during its industrial processing, decreasing the value of fibers, proteins, and minerals. Therefore, bread has become a product of high interest to increase its nutritional value. Due to the high consumption of bread, this paper provides a general description of the physicochemical and rheological changes of the dough, as well as the sensory properties of bread by incorporating alternative flours such as beans, lentils, and soy (among others). The reviewed data show that alternative flours can improve fiber, macro, and micronutrient content. The high fiber content reduces the quality of the texture of the products. However, new processing steps or cooking protocols, namely flour proportions, temperature, cooking, and fermentation time, can allow adjusting production variables and optimization to potentially overcome the decrease in sensory quality and preserve consumer acceptance.

Tunable Fungal Monofilaments from Food Waste for Textile Applications

A fungal biorefinery is presented to valorize food waste to fungal monofilaments with tunable properties for different textile applications. Rhizopus delemar is successfully grown on bread waste and the fibrous cell wall is isolated. A spinnable hydrogel is produced from cell wall by protonation of amino groups of chitosan followed by homogenization and concentration. Fungal hydrogel is wet spun to form fungal monofilaments which underwent post-treatments to tune the properties. The highest tensile strength of untreated monofilaments is 65 MPa (and 4% elongation at break). The overall highest tensile strength of 140.9 MPa, is achieved by water post-treatment. Moreover, post-treatment with 3% glycerol resulted in the highest elongation % at break, i.e., 14%. The uniformity of the monofilaments also increased after the post-treatments. The obtained monofilaments are compared with commercial fibers using Ashby's plots and potential applications are discussed. The wet spun monofilaments are located in the category of natural fibers in Ashby's plots. After water and glycerol treatments, the properties shifted toward metals and elastomers, respectively. The compatibility of the monofilaments with human skin cells is supported by a biocompatibility assay. These findings demonstrate fungal monofilaments with tunable properties fitting a wide range of sustainable textiles applications.

Mechanism of action of three different glycogen branching enzymes and their effect on bread quality

Bread staling adversely affects the quality of bread, but starch modification by enzymes can counteract this phenomenon. Glycogen branching enzymes (GBEs) used in this study were isolated from Deinococcus geothermalis (DgGBE), Escherichia coli (EcGBE), and Vibrio vulnificus (VvGBE). These enzymes were characterized and applied for starch dough modification to determine their role in improving bread quality. First, the branching patterns, activity on amylose and amylopectin, and thermostability of the GBEs were determined and compared. EcGBE and DgGBE exhibited better thermostable characteristics than VvGBE, and all GBEs exhibited preferential catalysis of amylopectin over amylose but different degrees. VvGBE and DgGBE produced a large number of short branches. Three GBEs degraded the starch granules and generated soluble polysaccharides. Moreover, the maltose was increased in the starch slurry but most significantly in the DgGBE treatment. Degradation of the starch granules by GBEs enhanced the maltose generation of internal amylases. When used in the bread-making process, DgGBE and VvGBE increased the dough and bread volume by 9 % and 17 %, respectively. The crumb firmness and retrogradation of the bread were decreased and delayed significantly more in the DgGBE bread. Consequently, this study can contribute to understanding the detailed roles of GBEs in the baking process.

Biofilm development of Candida boidinii and the effect of tyrosol on biofilm formation

OBJECTIVES

The applicability of a simple and high-throughput method for quantitative characterization of biofilm formation by Candida boidinii was tested in order to evaluate the effects of exogenous tyrosol on yeast growth and biofilm formation capacity.

RESULTS

Significant concentration-, temperature and time-dependent effect of tyrosol (2-(4-hydroxyphenyl)ethanol) was demonstrated, but it differentially affected the growth and biofilm formation (characterized by crystal violet staining and XTT-reduction assay) of Candida boidinii. Testing biofilm based on metabolic activity displayed sensitively the differences in the intensity of biofilm in terms of temperature, tyrosol concentration, and exposure time. At 22 °C after 24 h none of the tyrosol concentrations had significant effect, while at 30 °C tyrosol-mediated inhibition was observed at 50 mM and 100 mM concentration. After 48 h and 72 h at 22 °C, biofilm formation was stimulated at 6.25-25 mM concentrations, meanwhile at 30 °C tyrosol decreased the biofilm metabolic activity proportionally with the concentration.

CONCLUSIONS

The research concludes that exogenous tyrosol exerts unusual effects on Candida boidinii growth and biofilm formation ability and predicts its potential application as a regulating factor of various fermentations by Candida boidinii.

Psyllium husk gel used as an alternative and more sustainable scalding technology for wheat bread quality improvement and acrylamide reduction

This study aimed at evaluating the influence of different amounts (5, 10, 15, 20, and 25%) of psyllium husk gel (PHG) on wheat bread (WB) characteristics - chiefly, overall acceptability (OA), porosity, specific volume (v), mass loss after baking (ML), shape retention coefficient, crust and crumb color coordinates, bread crumb hardness during storage, saccharides content, and acrylamide (AA) concentration. PHG was prepared by mixing 100 g of psyllium husk powder with 800 mL of warm water. It was established that the amount of psyllium husk gel is a significant factor in dough redness (a*) (p < 0.001). A moderate positive correlation (r) was found between acrylamide content in wheat bread and maltose concentration in dough (r = 0.567). The psyllium husk gel increased the overall acceptability and specific volume of wheat bread. Wheat bread porosity showed a moderate positive correlation with mass loss after baking (r = 0.567) and a strong positive correlation with texture hardness (r = 0.664). Lower acrylamide content was obtained in wheat bread prepared with 5, 10, 15, 20, and 25% of psyllium husk gel (1.53, 2.34, 3.80, 2.69, and 3.62 times lower than the control wheat bread, respectively). Acrylamide content showed a strong positive correlation with the porosity of wheat bread (r = 0.672), with crust brightness (L*), and yellowness/blueness (b*) coordinates, as well as with crumb brightness, redness, and yellowness coordinates. Overall, psyllium husk gel hydrocolloids reduced acrylamide formation in wheat bread and can be recommended for the quality improvement of wheat bread.

Construction of versatile yeast plasmid vectors transferable by Agrobacterium-mediated transformation and their application to bread-making yeast strains

Agrobacterium-mediated transformation (AMT) potentially has great advantages over other DNA introduction methods: e.g., long DNA and numerous recipient strains can be dealt with at a time merely by co-cultivation with donor Agrobacterium cells. However, AMT was applied only to several laboratory yeast strains, and has never been considered as a standard gene-introduction method for yeast species. To disseminate the AMT method in yeast species, it is necessary to develop versatile AMT plasmid vectors including shuttle type ones, which have been unavailable yet for yeasts. In this study, we constructed a series of AMT plasmid vectors that consist of replicative (shuttle)- and integrative-types and harbor a gene conferring resistance to either G418 or aureobasidin A for application to prototrophic yeast strains. The vectors were successfully applied to five industrial yeast strains belonging to Saccharomyces cerevisiae after a modification of a previous AMT protocol, i.e., simply inputting a smaller number of yeast cells to the co-cultivation than that in the previous protocol. The revised protocol enabled all five yeast strains to generate recombinant colonies not only at high efficiency using replicative-type vectors, but also readily at an efficiency around 10-5 using integrative one. Further modification of the protocol demonstrated AMT for multiple yeast strains at a time with less labor. Therefore, AMT would facilitate molecular genetic approaches to many yeast strains in basic and applied sciences.

Valorization of an Old Variety of Triticum aestivum: A Study of Its Suitability for Breadmaking Focusing on Sensory and Nutritional Quality

"Avanzi 3-Grano 23" (G23) is an old variety of Triticum aestivum from the mountain areas of Lunigiana (north Tuscany, Italy), where traditional farming communities have contributed to its success and on-farm conservation. G23 flour, traditionally used for typical food products, is characterized by particular nutritional and sensory traits but has technological properties which limit its suitability for breadmaking. The aim of this work was to evaluate how to promote the use of G23 through the optimization of bread formulation by leveraging both flour blending and the leavening system. During the preliminary test, three different mixes of G23 flour and a strong flour (C) were tested in terms of their leavening power as a function of leavening agent (baker's yeast or sourdough). The selected M2 flour, composed of G23:C (1:1 w/w), was used for further breadmaking trials and 100% C flour was utilized as a control. The sourdough bread obtained with the M2 flour (SB-M2) showed an improved sensory profile compared with the related control (SB-C). Furthermore, SB-M2 exhibited the best aromatic (high content in aldehydes, pyrazines and carboxylic acids) and phytochemical profile (total polyphenols and flavonoids content and antioxidant activity). In contrast, the use of baker's yeast, although optimal from the point of view of breadmaking, did not result in the same levels of aromatic complexity because it tends to standardize the product without valorizing the sensory and nutritional qualities of the flour. In conclusion, in the experimental conditions adopted, this old wheat variety appears to be suitable for the production of sourdough bakery products.

Improving the Leavening Effect of Ice like CO2 Gas Hydrates by Addition of Gelling Agents in Wheat Bread

This article brings together the application of ice-like CO2 gas hydrates (GH) as a leavening agent in wheat bread along with the incorporation of some natural gelling agents or flour improvers into the bread to enhance the textural properties of the wheat bread. The gelling agents used for the study were ascorbic acid (AC), egg white (EW), and rice flour (RF). These gelling agents were added to the GH bread containing different amounts of GH (40, 60, and 70% GH). Moreover, a combination of these gelling agents in a wheat GH bread recipe was studied for each respective percentage of GH. The combinations of gelling agents used in the GH bread were as follows: (1) AC, (2) RF + EW, and (3) RF + EW + AC. The best combination of GH wheat bread was 70% GH + AC + EW + RF combination. The primary goal of this research is to gain a better understanding of the complex bread dough created by CO2 GH and its influence on product quality when certain gelling agents are added to the dough. Moreover, the prospect of managing and modifying wheat bread attributes by the use of CO2 GH with the addition of natural gelling agents has not yet been researched and is a fresh idea in the food industry.

Strategies for Producing Low FODMAPs Foodstuffs: Challenges and Perspectives

In recent years, there has been a growing interest in a diet low in fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAPs) as a promising therapeutic approach to reduce the symptoms associated with irritable bowel syndrome (IBS). Hence, the development of low FODMAPs products is an important challenge for the food industry, and among the various foodstuffs associated with the intake of FODMAPs, cereal-based products represent an issue. In fact, even if their content in FODMAPs is limited, their large use in diet can be an important factor in developing IBS symptoms. Several useful approaches have been developed to reduce the FODMAPs content in processed food products. Accurate ingredient selection, the use of enzymes or selected yeasts, and the use of fermentation steps carried out by specific lactic bacteria associated with the use of sourdough represent the technical approaches that have been investigated, alone or in combination, to reduce the FODMAPs content in cereal-based products. This review aims to give an overview of the technological and biotechnological strategies applicable to the formulation of low-FODMAPs products, specifically formulated for consumers affected by IBS. In particular, bread has been the foodstuff mainly investigated throughout the years, but information on other raw or processed products has also been reported. Furthermore, taking into account the required holistic approach for IBS symptoms management, in this review, the use of bioactive compounds that have a positive impact on reducing IBS symptoms as added ingredients in low-FODMAPs products is also discussed.

Study of the Fermentation Characteristics of Non-Conventional Yeast Strains in Sweet Dough

Despite the diverse functions of yeast, only a relatively homogenous group of Saccharomyces cerevisiae yeasts is used in the baking industry. Much of the potential of the natural diversity of yeasts has not been explored, and the sensory complexity of fermented baked foods is limited. While research on non-conventional yeast strains in bread making is increasing, it is minimal for sweet fermented bakery products. In this study, the fermentation characteristics of 23 yeasts from the bakery, beer, wine, and spirits industries were investigated in sweet dough (14% added sucrose w/w dm flour). Significant differences in invertase activity, sugar consumption (0.78-5.25% w/w dm flour), and metabolite (0.33-3.01% CO₂; 0.20-1.26% ethanol; 0.17-0.80% glycerol; 0.09-0.29% organic acids) and volatile compound production were observed. A strong positive correlation (R² = 0.76, p < 0.001) between sugar consumption and metabolite production was measured. Several non-conventional yeast strains produced more positive aroma compounds and fewer off-flavors than the reference baker's yeast. This study shows the potential of non-conventional yeast strains in sweet dough.

Multi-scale dough adhesion analysis: Relation between laboratory scale, pilot scale and human sensory

Undesired dough adhesion is still a challenge during the production of baked goods. There are various methods for determining the adhesive texture properties of dough. In the majority of scientific papers, dough stickiness is measured analytically by the force-distance recording of dough detachment. In this study, we describe a new multi-scale approach to compare dough adhesion phenomena in a laboratory, pilot sale and human sensory assessment. In it, the adhesive material properties of dough were investigated using a pilot scale toppling device representing dough adhesion behavior in the production process, in the laboratory by texture analysis with the Chen-Hoseney method and furthermore with a new, implemented non-oral human sensory analysis. To simulate different dough adhesion behavior, the dough mechanical and adhesion properties were varied by applying dough-modifying enzymes and different dough storage times. The structural changes in the different wheat dough system were compared by rheological characterization. By characterizing the different adhesion phenomena of the doughs, the sample with bacterial xylanase showed the highest values after 80 min of storage time in all three methods. Correlation analysis revealed a strong relationship between the detachment time (pilot scale) and human sensory assessment attributes (Force R = 0.81, Time R = 0.87, Distance R = 0.92, Stickiness R = 0.80) after 80 min of storage time. Even though human sensory assessment showed limits in the detectability of differences in dough adhesion behavior compared to the Chen-Hoseney method, it was better suited to predict machinability.

A dynamic micro-scale dough foaming and baking analysis - Comparison of dough inflation based on different leavening agents

Leavening agents play a pivotal role in the production of baked goods. Through gas production the inner structure of the product gets its typical foam structure and textural appearance. Baking trials are thereby a common way to determine the achievable loaf volume, crumb structure and other product specific properties. The required material input for these classic baking trials is high, as well as specific baking skills are required to obtain comparable and reliable results. To minimize the previously mentioned challenges, an in-line kneading, proofing, and baking process in a conventional rheometer was used and a microscale method was developed to determine both flour-specific baking performance and leavening-dependent volume increase without sample transfer. The results show a direct comparability of standard baking tests and the microscale method with yeast. In a second step the influence of the commercial used acidifying agent in baking powder D-(+)-Glucono-1,5-lactone (GDL) was compared to l-galactono-1,4-lactone (GGL), an alternative that has the potential to be biotechnologically produced from pectin-rich plant biomass residues. The results showed that GGL produced carbon dioxide slower then GDL and could therefore be interesting for frozen or slow rising products especially for protein rich flours.

An Innovative Approach in the Baking of Bread with CO2 Gas Hydrates as Leavening Agents

Gas (guest) molecules are trapped in hydrogen-bonded water molecules to form gas hydrates (GH), non-stoichiometric solids that resemble ice. High pressure and low temperature are typical conditions for their development, with van der Waals forces joining the host and guest molecules. This article study investigates the application of CO2 gas hydrates (CO2 GH) as a leavening agent in baking, with particular reference to the production of wheat bread. The main intention of this study is to better understand the complex bread dough formed by CO2 GH and its impact on product quality. This may enable the adaptation of CO2 GH in baking applications, such as those that can specifically influence wheat bread properties, and so the final bread quality. The present research further examines the comparative evaluation of yeast bread with the GH bread's impact on bread quality parameters. The amount of GH was varied from 10 to 60%/amount of flour for the GH breads. The GH breads were compared with the standard yeast bread for different quality parameters such as volume, texture, and pore analysis. The results show that the bread with 20% and 40% GH obtained the best results in terms of volume and pore size. Moreover, this article also sheds some light on the future applications of the use of CO2 GH as leavening agents in foods. This knowledge could help to create new procedures and criteria for improved GH selection for applications in bread making and other bakery or food products.

Relating the protein composition and air-water interfacial properties of aqueous flour extracts from wheats grown at different nitrogen fertilization levels

Aqueous phase extractable proteins from wheat can play a functional role in foods requiring interfacial stabilization. We here investigated the (protein) composition of aqueous flour extracts from wheats grown at different nitrogen (N) fertilization levels and studied their air-water interfacial characteristics. An important finding was that α- and γ-gliadins were extracted from wheat flour with water, even to an extent that they in the present work comprised 62-71% of the extract proteins. Application of N fertilization during wheat cultivation led to flour extracts with higher foam stabilities and air-water interface dilatational moduli. In all cases, proteins were found to most likely be the dominant constituent at the air-water interface. Analysis of foam protein compositions revealed an enrichment of proteins with molecular weights matching those of α- and γ-gliadins. It thus seems that gliadins can to a large extent determine the foaming characteristics of aqueous wheat flour extracts.

Maltose-Negative Yeast in Non-Alcoholic and Low-Alcoholic Beer Production

Although beer is a widely used beverage in many cultures, there is a need for a new drinking alternative in the face of rising issues such as health concerns or weight problems. However, non-alcoholic and low-alcoholic beers (NABLAB) still have some sensory problems that have not been fully remedied today, such as “wort-like”/”potato-like” flavours or a lack of aroma. These defects are due to the lack of alcohol (and the lack of the aldehyde-reducing effect of alcohol fermentation), as well as production techniques. The use of new yeast strains that cannot ferment maltose—the foremost sugar in the wort—is highly promising to produce a more palatable and sustainable NABLAB product because production with these yeast strains can be performed with standard brewery equipment. In the scientific literature, it is clear that interest in the production of NABLAB has increased recently, and experiments have been carried out with maltose-negative yeast strains isolated from many different environments. This study describes maltose-negative yeasts and their aromatic potential for the production of NABLAB by comprehensively examining recent academic studies.

Baker’s yeast (Saccharomyces cerevisiae) catalyzed synthesis of bioactive heterocycles and some stereoselective reactions

Saccharomyces cerevisiae, commonly known as baker’s yeast, has gained significant importance as a mild, low-cost, environmentally benign biocatalyst. Initially it was mostly employed as an efficient catalyst for the enantioselective reduction of carbonyl compounds. Over the last decade, baker’s yeast has found versatile catalytic applications in various organic transformations. Many multicomponent reactions were also catalyzed by baker’s yeast. Various heterocyclic scaffolds with immense biological activities were synthesized by employing baker’s yeast as catalyst at room temperature. In this communication, we have summarized baker’s yeast catalyzed various organic transformations focusing primarily on heterocyclic synthesis.

Sugar Levels Determine Fermentation Dynamics during Yeast Pastry Making and Its Impact on Dough and Product Characteristics

Fermented pastry products are produced by fermenting and baking multi-layered dough. Increasing our knowledge of the impact of the fermentation process during pastry making could offer opportunities for improving the production process or end-product quality, whereas increasing our knowledge on the sugar release and consumption dynamics by yeast could help to design sugar reduction strategies. Therefore, this study investigates the impact of yeast fermentation and different sugar concentrations on pastry dough properties and product quality characteristics. First, yeasted pastry samples were made with 8% yeast and 14% sucrose on a wheat flour dry matter base and compared to non-yeasted samples. Analysis of saccharide concentrations revealed that sucrose was almost entirely degraded by invertase in yeasted samples after mixing. Fructans were also degraded extensively, but more slowly. At least 23.6 ± 2.6% of the released glucose was consumed during fermentation. CO₂ production during fermentation contributed more to product height development than water and ethanol evaporation during baking. Yeast metabolites weakened the gluten network, causing a reduction in dough strength and extensibility. However, fermentation time had a more significant impact on dough rheology parameters than the presence of yeast. In balance, yeast fermentation did not significantly affect the calculated sweetness factor of the pastry product with 14% added sucrose. Increasing the sugar content (21%) led to higher osmotic stress, resulting in reduced sugar consumption, reduced CO₂ and ethanol production and a lower product volume. A darker colour and a higher sweetness factor were obtained. Reducing the sugar content (7%) had the opposite effect. Eliminating sucrose from the recipe (0%) resulted in a shortened productive fermentation time due to sugar depletion. Dough rheology was affected to a limited extent by changes in sucrose addition, although no sucrose addition or a very high sucrose level (21%) reduced the maximum dough strength. Based on the insights obtained in this study, yeast-based strategies can be developed to improve the production and quality of fermented pastry.

Effects of Quinoa Flour on Wheat Dough Quality, Baking Quality, and in vitro Starch Digestibility of the Crispy Biscuits

Quinoa is a pseudo-cereal which has excellent nutritional and functional properties due to its high content of nutrients, such as polyphenols and flavonoids, and therefore quinoa serves as an excellent supplement to make healthy and functional foods. The present study was aimed to evaluate the quality characteristics of wheat doughs and crispy biscuits supplemented with different amount of quinoa flour. The results showed that when more wheat flour was substituted by quinoa flour, proportion of unextractable polymeric protein to the total polymeric protein (UPP%) of the reconstituted doughs decreased and the gluten network structure was destroyed at a certain substitution level. The content of B-type starch and the gelatinization temperature of the reconstituted flours increased. The storage modulus, loss modulus, development time, and stability time of the dough increased as well. Moreover, hardness and toughness of the formulated crispy biscuits significantly decreased. Analyses suggested that starch digestibility was reduced and resistant starch content increased significantly. Taken together, quinoa flour improved dough rheological properties, enhanced the textural properties, and increased resistant starch content in crispy biscuits, thus adding to high nutritional value.

A Study on the Applicability of Thermodynamic Sensors in Fermentation Processes in Selected Foods

This study focuses on the use of thermodynamic sensors (TDS) in baking, brewing, and yogurt production at home. Using thermodynamic sensors, a change in the temperature flow between the two sensor elements during fermentation was observed for the final mixture (complete recipe for pizza dough production), showing the possibility of distinguishing some phases of the fermentation process. Even during the fermentation process in the preparation of wort and yogurt with non-traditional additives, the sensors were able to indicate significant parts of the process, including the end of the process. The research article also mentions as a new idea the use of trivial regulation at home in food production to determine the course of the fermentation process. The results presented in this article show the possibility of using TDS for more accurate characterization and adjustment of the production process of selected foods in the basic phase, which will be further applicable in the food industry, with the potential to reduce the cost of food production processes that involve a fermentation process.

The dough-strengthening and spore-sterilizing effects of mannosylerythritol lipid-A in frozen dough and its application in bread making

Biosurfactants have been put into applications in breadmaking industry, while the effects of mannosylerythritol lipid-A (MEL-A) on gluten network of frozen dough, bread quality and microbial spoilage were firstly investigated in this study. Rheology and differential scanning calorimetry (DSC) analysis showed that MEL-A significantly improved the rheological properties of frozen dough and reduced the content of frozen water. Further experiments showed that MEL-A promoted the formation of aggregates by interacting with gluten protein, and strengthened the gluten network through molecular weight distribution measurement and microstructure observation, effectively avoiding the destruction of ice crystals. A series of bread assessments illustrated MEL-A improved the loaf volume, gas retention ability and textural property. In addition, MEL-A (1.5%) killed 99.97% of the vegetative cells of Bacillus cereus and 75.54% of the spores, and at the same time had a slight inactivation effect on yeast. These results indicate that MEL-A has broad application prospects in the baking industry and the storage stage of flour products.

Evolutionary engineering to improve Wickerhamomyces subpelliculosus and Kazachstania gamospora for baking

The conventional baker's yeast, Saccharomyces cerevisiae, is the indispensable baking yeast of all times. Its monopoly coupled to its major drawbacks, such as streamlined carbon substrate utilisation base and a poor ability to withstand a number of baking associated stresses, prompt the need to search for alternative yeasts to leaven bread in the era of increasingly complex consumer lifestyles. Our previous work identified the inefficient baking attributes of Wickerhamomyces subpelliculosus and Kazachstania gamospora as well as preliminarily observations of improving the fermentative capacity of these potential alternative baker's yeasts using evolutionary engineering. Here we report on the characterisation and improvement in baking traits in five out of six independently evolved lines incubated for longer time and passaged for at least 60 passages relative to their parental strains as well as the conventional baker's yeast. In addition, the evolved clones produced bread with a higher loaf volume when compared to bread baked with either the ancestral strain or the control conventional baker's yeast. Remarkably, our approach improved the yeasts' ability to withstand baking associated stresses, a key baking trait exhibited poorly in both the conventional baker's yeast and their ancestral strains. W. subpelliculosus evolved the best characteristics attractive for alternative baker's yeasts as compared to the evolved K. gamospora strains. These results demonstrate the robustness of evolutionary engineering in development of alternative baker's yeasts.

Grain Composition and Quality in Portuguese Triticum&nbsp;aestivum Germplasm Subjected to Heat Stress after Anthesis

Bread wheat (Triticum aestivum) is a major crop worldwide, and it is highly susceptible to heat. In this work, grain production and composition were evaluated in Portuguese T. aestivum germplasm (landraces and commercial varieties), which was subjected to heat after anthesis (grain filling stage). Heat increased the test weight (TW) in Nabão, Grécia and Restauração, indicating an improved flour-yield potential. Mocho de Espiga Branca (MEB) and Transmontano (T94) showed higher thousand-kernel weight (TKW). Gentil Rosso presented increased soluble sugars, which are yeast substrates in the bread-making process. Ardila stood out for its protein increase under heat. Overall SDS was unaffected by higher temperature, but increased in T94, indicating a better dough elasticity for bread-making purposes. Under heat, lipid content was maintained in most genotypes, being endogenous fatty acids (FAs) key players in fresh bread quality. Lipid unsaturation, evaluated through the double bond index (DBI), also remained unaffected in most genotypes, suggesting a lower flour susceptibility to lipoperoxidation. In Grécia, heat promoted a higher abundance of monounsaturated oleic (C18:1) and polyunsaturated linoleic (C18:2) acids, which are essential fatty acids in the human diet. This work highlighted a great variability in most parameters both under control conditions or in response to heat during grain filling. Cluster analysis of traits revealed a lower susceptibility to heat during grain filling in Ardila, Restauração, and Ruivo, in contrast to MEQ, which seems to be more differentially affected at this stage. Characterization and identification of more favorable features under adverse environments may be relevant for agronomic, industrial, or breeding purposes, in view of a better crop adaptation to changing climate and an improved crop sustainability in agricultural systems more prone to heat stress.

Understanding gluten-free bread ingredients during ohmic heating: function, effect and potential application for breadmaking

Due to the absence of gluten, several challenges arise during gluten-free (GF) bread baking, affecting the mid-and-end-product quality. The main approach to overcome this issue is to combine certain functional ingredients and additives, to partially simulate wheat bread properties. In addition, the optimization of the baking process may contribute to improved product quality. A recent and very promising alternative to conventional baking is the use of ohmic heating (OH). Due to its volumetric and uniform heating principle, crumb development during baking and consequently bread volume is improved, which enhances the overall GF bread quality. Depending on the GF formulation, critical factors such as the electrical conductivity and viscosity of the batter may vary, which have a significant effect on the OH process performance. Therefore, this review attempts to provide a deeper understanding of the functionality of GF bread ingredients and how these may affect critical parameters during the OH processing.

Nectar Yeast Community of Tropical Flowering Plants and Assessment of Their Osmotolerance and Xylitol-Producing Potential

Floral nectar is colonised by microbes, especially yeasts which alter the scent, temperature, and chemical composition of nectar, thereby playing an essential role in pollination. The yeast communities inhabiting the nectar of tropical flowers of India are not well explored. We isolated 48 yeast strains from seven different tropical flowering plants. Post MSP-PCR-based screening, 23 yeast isolates and two yeast-like fungi were identified, which belonged to 16 species of 12 genera viz. Candida (2 species), Aureobasidium (2 species), Metschnikowia (2 species), Meyerozyma (1 species), Saitozyma (1 species), Wickerhamomyces (1 species), Kodamaea (2 species), Pseudozyma (1 species), Starmerella (1 species), Hanseniaspora (1 species), Rhodosporidiobolus (1 species), Moesziomyces (1 species), and two putative novel species. All yeast strains were assessed for their osmotolerance abilities in high salt and sugar concentration. Among all the isolates, C. nivariensis (SRA2.2, SRA1.1 and SRA2.1), M. caribbica (SRA4.8 and SRA4.6), S. flava SRA4.2, and M. reukaufii SRA3.2 showed significant growth in high concentrations of sugar (40-50% glucose), as well as salt (12-15% NaCl). All 25 strains were also screened for their ability to utilise xylose to produce xylitol. Meyerozyma caribbica was the most efficient xylitol producer, wherein three strains of this species (SRA4.6, SRA4.1, and SRA4.8) generated 18.61 to 21.56 g l^-1 of xylitol, with 0.465-0.539 g g^-1 yields. Through this study, we draw attention towards the tropical floral nectar as a potential niche for the isolation of diverse, osmotolerant, and xylitol-producing yeasts. Such osmotolerant yeasts have potential applications in food industries and biofuel production.

Formation of Bioactive Tyrosine Derivatives during Sprouting and Fermenting of Selected Whole Grains

Sprouting is a popular method in cereal processing because sprouted grains are accepted to have high nutritional value. The increased proteolytic activity by sprouting increases the free amino acids in grains. It was hypothesized that an increased amount of tyrosine can be utilized by microorganisms during fermentation to form higher amounts of bioactive tyrosine derivatives. Sprouting increased the tyrosine and tyramine contents considerably, but increases and decreases in l-3,4-dihydroxyphenylalanine (l-DOPA) and dopamine were specific to the cereal. More tyramine, l-DOPA, and dopamine formation was observed during sourdough fermentation than that in yeast fermentation. As a result of the combined application of sprouting (48 h at 20 °C) and sourdough fermentation (36 h at 30 °C), the amounts of dopamine, l-DOPA, and tyramine found in rye were 27, 50, and 136 mg/kg, respectively. Cereal products rich in dopamine and l-DOPA can thus be produced as functional food ingredients with their positive effects on human health and mood.

Non-thermal emerging technologies as alternatives to chemical additives to improve the quality of wheat flour for breadmaking: a review

Wheat flour is the main ingredient used in the preparation of bread. Factors such as low gluten content and the addition of nontraditional ingredients in baking affect the quality of wheat flour and may limit its use in baking. With the increasing trend of "clean label" products, it may be interesting to develop and use physical processes to improve the quality of wheat flour and avoid the use of chemical additives. High hydrostatic pressure, non-thermal plasma, ultrasound, ozonation, ultraviolet light, and pulsed light treatments are non-thermal emerging technologies (NTETs) that have been studied for this purpose. They were originally developed to inactivate microorganisms and enzymes in foods. Additionally, these technologies can be used at low temperatures to modify the most important component of wheat flour, i.e., gluten and its fractions, which are responsible for the rheological properties of wheat flour dough. Thus, this review focuses on the effects of these NTETs by considering the following factors: (1) the technological properties of gluten, (2) gluten-starch interactions, (3) possible effects of NTETs on minor components of flours, and (4) the quality of wheat flour and the resulting final products.

Metabolomics as a Tool to Elucidate the Sensory, Nutritional and Safety Quality of Wheat Bread-A Review

Wheat (Triticum aestivum) is one of the most extensively cultivated and used staple crops in human nutrition, while wheat bread is annually consumed in more than nine billion kilograms over the world. Consumers’ purchase decisions on wheat bread are largely influenced by its nutritional and sensorial characteristics. In the last decades, metabolomics is considered an effective tool for elucidating the information on metabolites; however, the deep investigations on metabolites still remain a difficult and longtime action. This review gives emphasis on the achievements in wheat bread metabolomics by highlighting targeted and untargeted analyses used in this field. The metabolomics approaches are discussed in terms of quality, processing and safety of wheat and bread, while the molecular mechanisms involved in the sensorial and nutritional characteristics of wheat bread are pointed out. These aspects are of crucial importance in the context of new consumers’ demands on healthy bakery products rich in bioactive compounds but, equally, with good sensorial acceptance. Moreover, metabolomics is a potential tool for assessing the changes in nutrient composition from breeding to processing, while monitoring and understanding the transformations of metabolites with bioactive properties, as well as the formation of compounds like toxins during wheat storage.

Effects of Sprouting and Fermentation on Free Asparagine and Reducing Sugars in Wheat, Einkorn, Oat, Rye, Barley, and Buckwheat and on Acrylamide and 5-Hydroxymethylfurfural Formation during Heating

Usage of sprouted grains is an increasing trend in thermally processed foods. Sprouting alters the composition of sugars and amino acids, which are Maillard reaction precursors. Free asparagine, total free amino acids, and sugars were monitored during sprouting and yeast and sourdough fermentations. Acrylamide and 5-hydroxymethylfurfural (HMF) were analyzed in heated samples. The asparagine concentration decreased up to 40% after 24-36 h of sprouting, except for buckwheat, and then increased to the initial concentration after 48 h and several folds after 72 h. The increased amount of reducing sugars after sprouting caused higher acrylamide and HMF formation even if the asparagine concentration was lower. Acrylamide and HMF formation decreased after fermentation of sprouted wholemeal because sugars and asparagine were consumed by yeast. A pH drop of 3 units by sourdough fermentation decreased acrylamide formation but increased HMF formation. Results indicated that sprouted cereal products should be produced under controlled conditions to be used in heated foods.

Non-Conventional Yeasts as Alternatives in Modern Baking for Improved Performance and Aroma Enhancement

Saccharomyces cerevisiae remains the baker’s yeast of choice in the baking industry. However, its ability to ferment cereal flour sugars and accumulate CO2 as a principal role of yeast in baking is not as unique as previously thought decades ago. The widely conserved fermentative lifestyle among the Saccharomycotina has increased our interest in the search for non-conventional yeast strains to either augment conventional baker’s yeast or develop robust strains to cater for the now diverse consumer-driven markets. A decade of research on alternative baker’s yeasts has shown that non-conventional yeasts are increasingly becoming important due to their wide carbon fermentation ranges, their novel aromatic flavour generation, and their robust stress tolerance. This review presents the credentials of non-conventional yeasts as attractive yeasts for modern baking. The evolution of the fermentative trait and tolerance to baking-associated stresses as two important attributes of baker’s yeast are discussed besides their contribution to aroma enhancement. The review further discusses the approaches to obtain new strains suitable for baking applications.

Gas cell stabilization by aqueous-phase constituents during bread production from wheat and rye dough and oat batter: Dough or batter liquor as model system

Proper gas cell stability during fermentation and baking is essential to obtain high-quality bread. Gas cells in wheat dough are stabilized by the gluten network formed during kneading and, from the moment this network locally ruptures, by liquid films containing nonstarch polysaccharides (NSPs) and surface-active proteins and lipids. Dough liquor (DL), the supernatant after ultracentrifugation of dough, is a model system for these liquid films and has been extensively studied mostly in the context of wheat bread making. Nonwheat breads are often of lower quality (loaf volume and crumb structure) than wheat breads because their doughs/batters lack a viscoelastic wheat gluten network. Therefore, gas cell stabilization by liquid film constituents may be more important in nonwheat than in wheat bread making. This manuscript aims to review the knowledge on DL/batter liquor (BL) and its relevance for studying gas cell stabilization in wheat and nonwheat (rye and oat) bread making. To this end, the unit operations in wheat, rye, and oat bread making are described with emphasis on gas incorporation and gas cell (de)stabilization. A discussion of the knowledge on the recoveries and chemical structures of proteins, lipids, and NSPs in DLs/BLs is provided and key findings of studies dealing with foaming and air-water interfacial properties of DL/BL are discussed. Next, the extent to which DL/BL functionality can be related to bread properties is addressed. Finally, the extent to which DL/BL is a representative model system for the aqueous phase of dough/batter is discussed and related to knowledge gaps and further research opportunities.

Effect of By-Products from Selected Fruits and Vegetables on Gluten-Free Dough Rheology and Bread Properties

The aim of the study was to investigate the effect of using various by-products (orange and apple pomace, tomato peel, pepper peel, prickly pear peel, and prickly pear seed peel) on the dough rheology and properties of gluten-free bread. The by-products were incorporated into a gluten-free bread formulation based on corn and chickpea flours (2/1 w/w). Different levels of each by-product (0, 2.5, 5, and 7.5% in the basic replacement) were tested. Wheat bread and gluten-free bread without the addition of by-products were used as controls. The results indicated that the by-products increased the maximum dough height, the total CO2 production, and CO2 retention coefficient compared to unenriched gluten-free dough. The highest K-value consistency coefficient was observed for the dough enriched with the prickly pear peel. The addition of by-products significantly improved (p < 0.0001) the specific volume of gluten-free bread, with values increasing from 1.48 to 2.50 cm3/g. The hierarchical cluster analysis and the constellation plot showed four groups: the wheat bread group, the second group containing the gluten-free control bread, the group with bread enriched by pomace, and the group with bread enriched with peels, exhibit the same effect on gluten-free bread and the peels exhibit the same effect on gluten-free bread.

Quality of wheat breads enriched with flour from germinated amaranth seeds

Amaranth flour from germinated (GA) and non-germinated (A) seeds (0%-C, 5%, 15%, 25%) were mixed with wheat flour for breadmaking. Fermentation parameters of dough (time-tf, maximum volume-V_max) were obtained. Specific volume (Vsp) of breads, crust color, texture and relaxation of crumb were analyzed. A high amount of germinated amaranth flour decreased V_max and increased tf, obtaining breads with low Vsp and darkness crust. A firmed and chewy crumb, although with a more aerated structure (high area occupied by alveoli) was obtained. The GA25 bread presented the softer crumb. The elastic modulus-E₁ of crumb increased and the relaxation time-T₁ decreased with higher amounts of amaranth flour, suggesting the formation of a more structured crumb; mainly in the case of non-germinated amaranth flour. Wheat flour resisted the inclusion of 25% of germinated amaranth seeds (GA25) without substantial changes in bread quality.

Thermal-aggregation behavior of gluten in frozen dough induced by ε-poly-L-lysine treated yeast

ε-poly-L-lysine treated yeast (PTY) helps to enhance the freeze-thaw tolerance of frozen dough. This study explored the effect of PTY on the aggregation and the gas-retention of frozen dough after steaming for 2, 5, 10, and 20 min. Gas-cell images showed that PTY reduced the loss of gas-retention ability caused by 4 times of freeze-thaw. The results of sodium dodecyl sulfate extractability and subunit distribution of gluten showed that, after the same heat time, frozen dough with PTY has higher degree of covalent crosslinking with better aggregation ability of α-, γ-gliadin, and low molecular weight glutenin subunits than frozen dough with yeast. Chemical analysis and chain morphology results demonstrated that the levels of acidity, NH₂, and free sulfhydryl in dough were decreased, and the protein molecules aggregated into longer chains when using PTY instead of yeast, indicating that PTY reduced acid-mediated hydrolysis and increased the disulfide bonds-mediated gluten polymerization.

Comprehensive Analyses of Carbohydrates, 1,2-Dicarbonyl Compounds, and Advanced Glycation End Products in Industrial Bread Making

The technology of bread making is characterized by three major steps: dough mixing, proofing, and baking. To follow the course of Maillard processes in an authentic food matrix, the complete manufacturing process of wheat bread rolls was assessed along all production steps with the quantitation of sugars, furfurals, 1,2-dicarbonyl compounds, and advanced glycation end products (AGEs). As a result, the AGE profile was significantly enlarged to more than 12 structures, and comprehensive mechanistic insights were provided. The analyses of five major German bread types including wheat, brown, rye bread, pumpernickel, and crispbreads led to AGE contents of 69-149 mg/kg bread or 984-1857 mg/kg protein. Major lysine protein modifications were carboxymethyl, carboxyethyl, and formyl lysine and pyrraline. Arginine was mainly modified by methylglyoxal (MGO) to give imidazolinones. A major part of MGO was confirmed to stem from microbial metabolism.