Sourdough-Based Biotechnologies for the Production of Gluten-Free Foods

Application of sourdough in gluten-free bakery products

ABSTRACTSIn recent years, the demand for gluten-free (GF) bakery products has grown rapidly due to the remarkable rising number of celiac patients and the increasing health awareness of GF products. However, GF products generally suffer from defects such as poor sensorial level, low nutritional value, high prices and short shelf life. Sourdough is the important starter culture applied in bakery field, and it has been proven to be ideal for enhancing the overall quality of bakery products. This review aims to systematically reviewed the application of sourdough in GF bakery products and its improvement to GF bakery products in terms of texture, shelf life, nutrition and flavor. Its positive effects derive from the complex metabolic activities of sourdough microorganisms, such as acidification, proteolysis, production of exopolysaccharides (EPS), activation of endogenous enzymes, and production of antibacterial substances. Finally, researchers are encouraged to expand the use of sourdough in GF bakery products to increase the variety of GF products. And the technical and nutritional potential of sourdough should be developed more widely.

Mechanism of carbohydrate and protein conversion during sourdough fermentation: An analysis based on representative Chinese sourdough microbiota

Sourdough fermentation is attracting growing attention because of its positive effects on properties of leavened baked good. However, the changes in dough features and the mechanisms behind them are not well understood, which limits its widespread use. In this study, we assessed the effects of representative lactic acid bacteria in sourdough monoculture or co-culture with yeasts on dough characteristics. Physicochemical analysis identified increased proteolysis and enhanced nutritional properties of co-culture groups. However, a reduction in organic acids contents of co-culture groups compared to monoculture was detected, and this effect was not limited by the yeast species. The RNA sequencing further demonstrated that the presence of yeast enhanced the protein metabolic activity of lactic acid bacteria, while decreased its organic acid biosynthetic activity. Moreover, the proteomic analysis revealed that endogenous metabolic proteins of flour, such as pyruvate kinase, glucosyltransferase and pyruvate dehydrogenase play a key role in carbohydrate metabolism during fermentation. This study uncovered the influence of typical microorganisms and endogenous enzymes on dough characteristics based on different aspects. Bacteria-mediated consumption of proteins and increased proteolysis in co-culture groups may underlie the improved digestibility and nutritional effects of sourdough fermented products, which provides an important basis for nutrient fortified bread making with multi-strain leavening agent.

Unlocking the potential of low FODMAPs sourdough technology for management of irritable bowel syndrome

Consumption of high FODMAP (Fermentable Oligo-, Di-, and Monosaccharides and Polyols) diet is the leading cause of alteration in the human gut microbiome, thereby, causing irritable bowel syndrome (IBS). Therefore, sourdough technology can be exploited for reduction of FODMAPs in various foods to alleviate the symptoms of IBS. Several microorganisms viz. Pichia fermentans, Lactobacillus fetmentum, Saccharomyces cerevisiae, Torulaspora delbrueckii, Kluyveromyces marxianus etc. have been identified for the production of low FODMAP type II sourdough fermented products. However, more research on regulation of end-product and volatilome profile is required for maximal exploitation of FODMAP-reducing microorganisms. Therefore, the present review is focused on utilisation of lactic acid bacteria and yeasts, alone and in synergy, for the production of low FODMAP sourdough foods. Moreover, the microbial bioprocessing of cereal and non-cereal based low FODMAP fermented sourdough products along with their nutritional and therapeutic benefits have been elaborated. The challenges and future prospects for the production of sourdough fermented low FODMAP foods, thereby, bringing out positive alterations in gut microbiome, have also been discussed.

Development of Functional Gluten-Free Sourdough Bread with Pseudocereals and Enriched with Moringa oleifera

Celiac patients tend to have an unbalanced diet, because gluten-free products typically contain a high amount of fats and carbohydrates and a low amount of proteins, minerals, and dietary fiber. This research focused on the development of gluten-free functional breads using pseudocereals, psyllium, and gluten-free sourdough to replace commercial yeast, fortifying them with Moringa oleifera. Six different gluten-free breads were made with sourdough: three control breads differentiated by sourdough (quinoa, amaranth, and brown rice) and three breads enriched with moringa leaf differentiated by sourdough. The antioxidant capacity, phenolic compounds, nutritional composition, physicochemical parameters (color, pH, and acidity), folate content, amino acid profile, reducing sugars, mineral composition, mineral bioaccessibility, fatty acid profile, and sensory acceptability were evaluated. A commercial gluten-free (COM) bread was included in these analyses. Compared with COM bread, the reformulated breads were found to have better nutritional properties. Moringa leaf increased the nutritional properties of bread, and highlighted the QM (quinoa/moringa) bread as having increased protein, fiber, sucrose, glucose, maltose, phenylalanine, and cysteine. The AM (amaranth/moringa) bread was also shown to have a higher total folate content, antioxidant capacity, phenolic compounds, 9t,11t-C18:2 (CLA), and 9t-C18:1. Reformulated breads enriched with moringa could meet nutritional requirements and provide health benefits to people with celiac disease.

Evaluation of Microbial Dynamics of Kombucha Consortia upon Continuous Backslopping in Coffee and Orange Juice

The kombucha market is diverse, and competitors constantly test new components and flavours to satisfy customers' expectations. Replacing the original brewing base, adding flavours, or using "backslopping" influence the composition of the symbiotic starter culture of bacteria and yeast (SCOBY). Yet, deep characterisation of microbial and chemical changes in kombucha consortia in coffee and orange juice during backslopping has not been implemented. This study aimed to develop new kombucha beverages in less-conventional matrices and characterise their microbiota. We studied the chemical properties and microbial growth dynamics of lactic-acid-bacteria-tailored (LAB-tailored) kombucha culture by 16S rRNA next-generation sequencing in coffee and orange juice during a backslopping process that spanned five cycles, each lasting two to four days. The backslopping changed the culture composition and accelerated the fermentation. This study gives an overview of the pros and cons of backslopping technology for the production of kombucha-based beverages. Based on research conducted using two different media, this work provides valuable information regarding the aspects to consider when using the backslopping method to produce novel kombucha drinks, as well as identifying the main drawbacks that need to be addressed.

The Gliadin Hydrolysis Capacity of B. longum, L. acidophilus, and L. plantarum and Their Protective Effects on Caco-2 Cells against Gliadin-Induced Inflammatory Responses

BACKGROUND

Non-celiac wheat sensitivity (NCWS) is a poorly understood gluten-related disorder (GRD) and its prominent symptoms can be ameliorated by gluten avoidance. This study aimed to determine the effectiveness of a probiotic mixture in hydrolyzing gliadin peptides (toxic components of gluten) and suppressing gliadin-induced inflammatory responses in Caco-2 cells.

METHODS

Wheat dough was fermented with a probiotic mix for 0, 2, 4, and 6 h. The effect of the probiotic mix on gliadin degradation was monitored by SDS-PAGE. The expression levels of IL-6, IL-17A, INF-γ, IL-10, and TGF-β were evaluated using ELISA and qRT-PCR methods.

RESULTS

According to our findings, fermenting wheat dough with a mix of B. longum, L. acidophilus, and L. plantarum for 6 h was effective in gliadin degradation. This process also reduced levels of IL-6 (p = 0.004), IL-17A (p = 0.004), and IFN-γ (p = 0.01) mRNA, as well as decreased IL-6 (p = 0.006) and IFN-γ (p = 0.0009) protein secretion. 4 h fermentation led to a significant decrease in IL-17A (p = 0.001) and IFN-γ (p = 0.003) mRNA, as well as reduced levels of IL-6 (p = 0.002) and IFN-γ (p < 0.0001) protein secretion. This process was also observed to increase the expression levels of IL-10 (p < 0.0001) and TGF-β (p < 0.0001) mRNA.

CONCLUSIONS

4 h fermentation of wheat flour with the proposed probiotic mix might be a good strategy to develop an affordable gluten-free wheat dough for NCWS and probably other GRD patients.

Exploiting the Native Microorganisms from Different Food Matrices to Formulate Starter Cultures for Sourdough Bread Production

The use of sourdough for bread production involves fermentation, which is dominated by lactic acid bacteria (LAB) and yeast. Sourdough can be inoculated with a starter culture or through a food matrix containing microorganisms to initiate sourdough fermentation. Sourdough is used as leavening agent for bread making, and metabolites produced by LAB and yeast confer a specific aroma and flavor profile to bread, thus improving its sensory attributes. However, few publications report the effect of microorganisms from different food products and by-products on sourdough fermentation. This review focuses on using different starter cultures from various food sources, from wheat flour to starter cultures. Additionally, included are the types of sourdough, the sourdough fermentation process, and the biochemical transformations that take place during the sourdough fermentation process.

The Ability of the Yeast Wickerhamomyces anomalus to Hydrolyze Immunogenic Wheat Gliadin Proteins

Gliadins proteins make up around 30% of total wheat flour proteins. They are involved in many immune disorders affecting an increasing number of people who eat foods made with wheat flour. The triggering factor is the accumulation in the gut of immunogenic peptides derived from incomplete degradation of gliadins by gastric proteases. Previous research has revealed the effectiveness of sourdough-fermentation technology or related lactic acid bacteria in reducing wheat flour allergenic proteins. However, there are no single yeast cultures for producing reduced allergenicity wheat products. This study evaluated sourdough-related yeast Wickerhamomyces anomalus strains for their ability to hydrolyze gliadin proteins. All yeast strains were able to degrade gliadins and use them as carbon and nitrogen sources. The proliferation of the yeast strains depended on the gliadin addition; complete hydrolysis was observed after 24 h. The strain showing higher proteolytic activity fermented, acceptably wheat flour dough. The gliadin content of the leavened dough was reduced by 50%. Bread made from the W. anomalus-fermented dough showed a 78% reduction in immunogenic α-gliadins. 50% of the decrease was attributed to the proteolytic activity of the yeast cells, and the other 35% to the baking process. These results show the potential of the yeast W. anomalus as a starter for reducing immunogenicity wheat products.

Effect of Bioprocessing on Techno-Functional Properties of Climate-Resilient African Crops, Sorghum and Cowpea

Sorghum and cowpea are very compatible for intercropping in hot and dry environments, and they also have complementary nutritional compositions. Thus, the crops have the potential to improve food security in regions threatened by climate change. The aim of this study was to investigate different enzymes (carbohydrate-degrading, proteases and phytases) and lactic acid bacteria (LAB) fermentation to improve the techno-functional properties of sorghum and cowpea flours. Results show that sorghum carbohydrates were very resistant to hydrolysis induced by bioprocessing treatments. Most of the protease treatments resulted in low or moderate protein solubilization (from ca. 6.5% to 10%) in sorghum, while the pH adjustment to 8 followed by alkaline protease increased solubility to 40%. With cowpea, protease treatment combined with carbohydrate-degrading enzymes increased the solubility of proteins from 37% up to 61%. With regard to the techno-functional properties, LAB and amylase treatment decreased the sorghum peak paste viscosities (from 504 to 370 and 325 cPa, respectively), while LAB and chemical acidification increased cowpea viscosity (from 282 to 366 and 468 cPa, respectively). When the bioprocessed sorghum and cowpea were tested in breadmaking, only moderate effects were observed, suggesting that the modifications by enzymes and fermentation were not strong enough to improve breadmaking.

Sorghum Flour Application in Bread: Technological Challenges and Opportunities

Sorghum has a long history of use in the production of different types of bread. This review paper discusses different types of bread and factors that affect the physicochemical, technological, rheological, sensorial, and nutritional properties of different types of sorghum bread. The main types of bread are unleavened (roti and tortilla), flatbread with a pre-ferment (injera and kisra), gluten-free and sorghum bread with wheat. The quality of sorghum flour, dough, and bread can be improved by the addition of different ingredients and using novel and traditional methods. Furthermore, extrusion, high-pressure treatment, heat treatment, and ozonation, in combination with techniques such as fermentation, have been reported for increasing sorghum functionality.

Antifungal Mechanisms and Application of Lactic Acid Bacteria in Bakery Products: A Review

Bakery products are nutritious, but they are susceptible to fungal contamination, which leads to a decline in quality and safety. Chemical preservatives are often used to extend the shelf-life of bakery products, but long-term consumption of these preservatives may increase the risk of chronic diseases. Consumers increasingly demand food with fewer chemical preservatives. The application of lactic acid bacteria (LAB) as a novel biological preservative not only prolongs the shelf-life of bakery products but also improves the baking properties of bakery products. This review summarizes different types and action mechanisms of antifungal compounds produced by LAB, factors affecting the production of antifungal compounds, and the effects of antifungal LAB on bakery products, providing a reference for future applications of antifungal LAB in bakery products.

Gluten-free bakery products: Ingredients and processes

There is an increasing demand for gluten-free products around the world because certain groups of people, which have increased in the last decades, need to eliminate gluten from their diet. A growing number of people consider gluten-free products to be healthier. However, making gluten-free products such as bread is a technological challenge due to the important role of the gluten network in their development. However, other products, such as cakes and cookies usually made with wheat flour, can easily be made with gluten-free starches or flours since gluten does not play an essential role in their production. To replace wheat flour in these elaborations it is necessary to resort to gluten-free starches and/or flours and to gluten substitutes. Additionally, it can be convenient to incorporate other ingredients such as proteins, fibers, sugars or oils, as well as to modify their quantities in wheat flour formulations. Regarding gluten-free flours, it will also be necessary to know the parameters that influence their functionality in order to obtain regular products. These problems have originated a lower availability of gluten-free products which have a worse texture and are less tasty and more expensive than their homologues with gluten. These problems have been partially solved thanks to research on these types of products, their ingredients and their production methods. In recent years, studies about the nutritional improvement of these products have increased. This chapter delves into the main ingredients used in the production of gluten-free products, the processes for making gluten-free breads, cakes and cookies, and the nutritional quality of these products.

Improvement of Texture, Nutritional Qualities, and Consumers’ Perceptions of Sorghum-Based Sourdough Bread Made with Pediococcus pentosaceus and Weissella confusa Strains

Enriched gluten-free products are in high demand owing to increasing celiac disease worldwide. Sourdough fermentation can improve the quality of gluten-free cereals, rendering the resulting product beneficial as a functional food. This study produced sorghum bread (SB) using sourdough technology and evaluated the texture, nutrition profile, bioactive components, and sensory attributes of the product. The base formula was composed of sorghum flour and corn starch. Sourdough made with Pediococcus pentosaceus LD7 (PL7), P. pentosaceus SA8 (PS8), or Weissella confusa SD8 (WS8) was added at a 20% substitution level for bread production, while bread without sourdough addition was used as the control sample. The texture profiles of the SB were significantly (p ˂ 0.05) softer than that of the control. The sourdough breads possessed higher crude protein, ash, and dietary fibre contents than the control bread. Tannin and total phenol contents were significantly (p ˂ 0.05) higher in the sourdough breads compared to the control sample. The specific volume of the sample made with PS8 sourdough was the highest at 2.50 cm3/g compared to the other samples (2.17–2.46 cm3/g). The sourdough samples had higher scores for taste, texture, aroma, and overall acceptability than the control, with PL7 SB exhibiting the best overall acceptability (6.56). This study established promising use of sourdough with starters as an ingredient for baked products with improved technological and nutritional attributes as well as consumer acceptability.

Phenotypic and genotypic characterisation of Lactobacillus and yeast isolates from a traditional New Zealand Māori potato starter culture

Parāroa Rēwena is a traditional Māori sourdough produced by fermentation using a potato starter culture. The microbial composition of the starter culture is not well characterised, despite the long history of this product. The morphological, physiological, biochemical and genetic tests were conducted to characterise 26 lactic acid bacteria (LAB) and 15 yeast isolates from a Parāroa Rēwena potato starter culture. The results of sugar fermentation tests, API 50 CHL tests, and API ID 32 C tests suggest the presence of four different LAB phenotypes and five different yeast phenotypes. 16S rRNA and 26S rRNA sequencing identified the LAB as Lacticaseibacillus paracasei and the yeast isolates as Saccharomyces cerevisiae, respectively. Multilocus sequence typing (MLST) of the L. paracasei isolates indicated that they had identical genotypes at the MLST loci, to L. paracasei subsp. paracasei IBB 3423 or L. paracasei subsp. paracasei F19. This study provides new insights into the microbial composition of the traditional sourdough Parāroa Rēwena starter culture.

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16S sequencing, Multilocus sequencing typing for LAB in the potato starter culture.

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26S sequencing for yeast in the starter culture.

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Lacticaseibacillus paracasei subsp. paracasei IBB3423.

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Lacticaseibacillus paracasei subsp. paracasei F19.

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Saccharomycescerevisiae.

Ancient Wheat Species: Biochemical Profile and Impact on Sourdough Bread Characteristics—A Review

In recent years, the attention of farmers, bakers and consumers towards ancient wheat species has been increasing. Low demands of pedo-climatic growth factors, the suitability for organic cultivation along with their high nutritional quality and their content in pro-health compounds make them extremely attractive for bakers and modern consumers, equally. On the other hand, in recent years, sourdough has gained attention due to its ability to produce new functionally active molecules with higher bioaccessibility and thus to produce bread with enhanced nutritional quality. This paper highlights the relevant nutritional profile of einkorn, spelt, emmer and Khorasan which could lead to bread with improved textural, sensorial, microbial and nutritional characteristics through sourdough fermentation. The ancient wheat species could be used as promising substitutes for common wheat flour for the design of innovative types of bread, even for special needs.

Sourdough production: fermentation strategies, microbial ecology, and use of non-flour ingredients

Sourdough production is an ancient method to ferment flour from cereals for the manufacturing of baked goods. This review deals with the state-of-the-art of current fermentation strategies for sourdough production and the microbial ecology of mature sourdoughs, with a particular focus on the use of non-flour ingredients. Flour fermentation processes for sourdough production are typically carried out by heterogeneous communities of lactic acid bacteria and yeasts. Acetic acid bacteria may also occur, although their presence and role in sourdough production can be criticized. Based on the inoculum used, sourdough productions can be distinguished in fermentation processes using backslopping procedures, originating from a spontaneously fermented flour-water mixture (Type 1), starter culture-initiated fermentation processes (Type 2), and starter culture-initiated fermentation processes that are followed by backslopping (Type 3). In traditional recipes for the initiation and/or propagation of Type 1 sourdough productions, non-flour ingredients are often added to the flour-water mixture. These ingredients may be the source of an additional microbial inoculum and/or serve as (co-)substrates for fermentation. An example of the former is the addition of yoghurt; an example of the latter is the use of fruit juices. The survival of microorganisms transferred from the ingredients to the fermenting flour-water mixture depends on the competitiveness toward particular strains of the microbial species present under the harsh conditions of the sourdough ecosystem. Their survival and growth is also determined by the presence of the appropriate substrates, whether or not carried over by the ingredients added.

Quinoa Flour, the Germinated Grain Flour, and Sourdough as Alternative Sources for Gluten-Free Bread Formulation: Impact on Chemical, Textural and Sensorial Characteristics

The demand for gluten-free breads has increased in the last years, but important quality and nutritional challenges remain unsolved. This research evaluated the addition of quinoa in whole quinoa grain flour, germinated quinoa flour, and quinoa sourdough, as a functional ingredient in the formulation of a rice flour-based bread. Twenty percent (w/w) of the rice flour was replaced with quinoa flour alternatives in bread formulations. The chemical composition, shelf-life, and sensory attributes of the rice-quinoa breads were analyzed. The addition of quinoa in sourdough resulted in breads with a significantly improved protein content at 9.82%, relative to 2.70% in the control breads. The amino acid content in quinoa sourdough breads also was also 5.2, 4.4, 2.6, 3.0, and 2.1 times higher in arginine, glutamic acid, leucine, lysine, and phenylalanine, respectively, relative to control breads with rice flour only. The addition of quinoa sourdough in rice breads also improved the texture, color, and shelf-life (up to 6 days), and thus they became moderately accepted among consumers. Although the germinated quinoa flour addition also resulted in a higher protein (9.77%) and amino acid content, they had a reduced shelf-life (4 days). Similarly, the addition of quinoa flour resulted in a higher protein content (9.61%), but the breads had poor texture attributes and were the least preferred by the consumers.

Hydrolytic enzymes and their directly and indirectly effects on gluten and dough properties: An extensive review

Poor water solubility, emulsifying, and foaming properties of gluten protein have limited its applications. Gluten is structured by covalent (disulfide bonds) and noncovalent bonds (hydrogen bonds, ionic bonds, hydrophobic bonds) which prone to alteration by various treatments. Enzyme modification has the ability to alter certain properties of gluten and compensate the deficiencies in gluten network. By hydrolyzing mechanisms and softening effects, hydrolytic enzymes affect gluten directly and indirectly and improve dough quality. The present review investigates the effects of some hydrolytic enzymes (protease and peptidase, alcalase, xylanase, pentosanase, and cellulase) on the rheological, functional, conformational, and nutritional features of gluten and dough. Overall, protease, peptidase, and alcalase directly affect peptide bonds in gluten. In contrast, arabinoxylan, pentosan, and cellulose are affected, respectively, by xylanase, pentosanase, and cellulase which indirectly affect gluten proteins. The changes in gluten structure by enzyme treatment allow gluten for being used in variety of purposes in the food and nonfood industry.

Sourdough Biotechnology Applied to Gluten-Free Baked Goods: Rescuing the Tradition

Recent studies suggest that the beneficial properties provided by sourdough fermentation may be translated to the development of new GF products that could improve their technological and nutritional properties. The main objective of this manuscript is to review the current evidence regarding the elaboration of GF baked goods, and to present the latest knowledge about the so-called sourdough biotechnology. A bibliographic search of articles published in the last 12 years has been carried out. It is common to use additives, such as hydrocolloids, proteins, enzymes, and emulsifiers, to technologically improve GF products. Sourdough is a mixture of flour and water fermented by an ecosystem of lactic acid bacteria (LAB) and yeasts that provide technological and nutritional improvements to the bakery products. LAB-synthesized biopolymers can mimic gluten molecules. Sourdough biotechnology is an ecological and cost-effective technology with great potential in the field of GF products. Further research is necessary to optimize the process and select species of microorganisms robust enough to be competitive in any circumstance.

Overcoming bread quality decay concerns: main issues for bread shelf life as a function of biological leavening agents and different extra ingredients used in formulation. A review

As is widely accepted, the quality decay of freshly baked bread that affects product shelf life is the result of a complex multifactorial process that involves physical staling, together with microbiological, chemical and sensorial spoilage. In this context, this paper provides a critical review of the recent literature about the main factors affecting shelf life of bread during post-baking. An overview of the recent findings about the mechanism of bread staling is firstly provided. Afterwards, the effect on staling induced by baker's yeasts and sourdough as well as by the extra ingredients commonly utilized for bread fortification is also addressed and discussed. As inclusion/exclusion criteria, only papers dealing with wheat bread and not with long-life bread or gluten-free bakery products are taken into consideration. Despite recent developments in international scientific literature, the whole mechanism that induces bread staling is far from being completely understood and the best analytical methods to be adopted to measure and/or describe in depth this process appear still debated. In this topic, the effects induced on bread shelf life by the use of biological leavening agents (baker's yeasts and sourdough) as well as by some extra ingredients included in the bread recipe have been individuated as two key issues to be addressed and discussed in terms of their influence on the kinetics of bread staling. © 2020 Society of Chemical Industry.

Consumption of Sourdough Breads Improves Postprandial Glucose Response and Produces Sourdough-Specific Effects on Biochemical and Inflammatory Parameters and Mineral Absorption

To evaluate responses to different sourdough breads, six groups of rats were fed a conventional refined wheat bread with no sourdough content (C_WhB); a leavened spelt bread baked with Rebola sourdough (Re_SpB); a durum wheat bread with Rebola sourdough (Re_DuB); or a multigrain bread leavened with Rebola (Re_MGB), Carla (Ca_MGB), or San Francisco sourdough (SF_MGB). Compared to C_WhB-fed rats, Re_SpB-, Re_DuB-, and Re_MGB-fed animals showed lower postprandial blood glucose levels, whereas SF_MGB-fed rats displayed a decreased postprandial blood insulin response and glucose and insulin products. The 3 week intake of Ca_MGB decreased blood triacylglycerols and the relative apparent absorption (RAA) of Fe²⁺, Cu²⁺, and Zn²⁺, whereas Re_MGB-fed animals showed lower serum levels of the MCP-1 inflammatory marker and decreased the Fe RAA. The 3 week consumption of the multigrain bread produced sourdough-specific effects. Thus, Re_MGB-fed animals displayed higher insulin concentrations than Ca_MGB- and SF_MGB-fed rats and decreased blood MCP-1 levels compared to those of Ca_MGB-fed animals. In addition, Ca_MGB-fed rats showed lower serum triacylglycerol concentrations than those of Re_MGB- and SF_MGB-fed animals, whereas SF_MGB-fed rats displayed higher RAA values of Ca²⁺, Cu²⁺, Fe²⁺, Mg²⁺, and Zn²⁺ than their Re_MGB and Ca_MGB counterparts. These sourdough-specific effects could be related to changes in the contents of sugars and organic acids, acidity, microbial composition, and proteolytic activity among sourdoughs. Hence, the consumption of sourdough breads improved postprandial blood glucose and insulin responses and produced sourdough-specific effects on RAA and serum insulin and triacylglycerol and MCP-1 levels in rats, showing that SF_MGB has the most promising beneficial effects.

Reducing FODMAPs and improving bread quality using type II sourdough with selected starter cultures

This study focussed on lactic acid bacteria (LAB) screening for sourdough type II elaboration and evaluating the effects of sourdough fermentation in bread making, focussing mainly on reducing FODMAPs. After a technological performance screening, six strains (Levilactobacillus brevis, Weissella minor, Lactiplantibacillus plantarum, Leuconostoc citreum, Limosilactobacillus fermentum, and Companilactobacillus farciminis) were selected for sourdough preparation. Total titratable acidity, pH, specific volume, and enumeration of microorganisms were carried out on sourdoughs, doughs, and breads. Breads were subjected to texture profile and colour analysis, moulds and yeast enumeration, and total fructans (main group of FODMAPs) quantification. Breads produced with sourdough showed a significant reduction of fructans, greater acidity, volume, and better performance during storage when compared to fermentation using only baker's yeast. Including specific cultures as starters in sourdough reduced fructans content by >92%, thereby producing a low FODMAP bread suitable for Irritable Bowel Syndrome patients with improved nutritional and technological properties.

Design of a "Clean-Label" Gluten-Free Bread to Meet Consumers Demand

The market of gluten-free (GF) products has been steadily increasing in last few years. Due to the technological importance of gluten, the GF food production is still a challenge for the industry. Indeed, large quantities of fat, sugars, structuring agents, and flavor enhancers are added to GF formulations to make textural and sensorial characteristics comparable to conventional products, leading to nutritional and caloric intake imbalances. The formulation of the novel "clean-label" GF bread included a commonly used mixture of maize and rice flour (ratio 1:1) fortified with selected protein-rich flours. Naturally hydrocolloids-containing flours (psyllium, flaxseed, chia) were included in the bread formulation as structuring agents. A type-II sourdough was obtained by using a selected Weissella cibaria P9 and a GF sucrose-containing flour as substrate for fermentation to promote the exo-polysaccharides synthesis by the starter lactic acid bacterium. A two-step protocol for bread-making was set-up: first, the GF sourdough was fermented (24 h at 30 °C); then, it was mixed with the other ingredients (30% of the final dough) and leavened with baker's yeast before baking. Overall, the novel GF bread was characterized by good textural properties, high protein content (8.9% of dry matter) and in vitro protein digestibility (76.9%), low sugar (1.0% of dry matter) and fat (3.1% of dry matter) content, and an in vitro predicted glycemic index of 85.

Yeast Biodiversity in Fermented Doughs and Raw Cereal Matrices and the Study of Technological Traits of Selected Strains Isolated in Spain

Bakers use pure microorganisms and/or traditional sourdoughs as the leavening agent for making bread. The performance of each starter and the substances produced by the microorganisms greatly affect the dough rheology and features of breads. Modern sourdoughs inoculated with selected lactic acid bacteria and yeasts are microbiologically stable, safer than traditional sourdoughs, and easy to use. However, the commercial repertoire of baker’s yeasts is still limited. Therefore, there is a demand for new strains of yeast species, capable of conferring distinctive traits to breads made from a variety of agri-food matrices, in the design of innovative starters. In this context, we report the first comprehensive study on yeasts isolated from a wide range of fermented doughs, cereal flours, and grains of Spain. Nine yeast species were identified from 433 isolates, which were distributed among separate clades. Moreover, phenotypic traits of potential technological relevance were identified in selected yeast strains. Mother doughs (MDs) showed the greatest yeast biodiversity, whereas commercial Saccharomyces starters or related and wild strains often dominated the bakery doughs. A metataxonomic analysis of wheat and tritordeum MDs revealed a greater richness of yeast species and percentage variations related to the consistency, flour type, and fermentation time of MDs.

Analysis of Gluten in Dried Yeast and Yeast-Containing Products

Yeast are commonly used in the preparation of foods and beverages such as beer and bread and may also be used on their own as a source of nutrients and flavoring. Because of the historical connection of yeast to products made from wheat and barley, consumers maintaining a gluten-free diet can have concerns about the safety of yeast ingredients. Analyzing the safety of yeast and yeast-containing products presents some difficulties, as the yeast organisms actively degrade any gluten in the product, raising questions on the appropriateness of detection by traditional antibody-based methods. This study examines a variety of yeast and yeast-containing products by competitive ELISA and liquid chromatography-mass spectrometry for the estimated level of gluten proteins. While samples such as yeast extracts and nutritional yeast contained gluten levels below the 20 mg/kg (or parts per million, ppm) threshold defined by Codex Alimentarius, one baking yeast and a nutritional yeast supplement sample contained higher levels of gluten. This study demonstrates that both competitive ELISA and liquid chromatography-mass spectrometry provide similar results in the detection of wheat and barley gluten in yeast-containing products.

Effect of the Leavening Agent on the Compositional and Sensorial Characteristics of Bread Fortified with Flaxseed Cake

Health and well-being improvement is currently driving innovation in bread, using a wide variety of value-added compounds as extra ingredients, including food industry by-products in a circular economy concept. In this context, this research aimed at evaluating the effect of the fortification of bread with different percentages of flaxseed cake, comparing two leavening agents: sourdough and baker’s yeast. Sensorial, physicochemical, and nutritional properties, including pH, the main fermentative metabolites, fatty acids, total phenols, antioxidant capacity, and volatile organic compounds were determined for fortified bread. The results showed a significant improvement of nutraceutical profile of the bread fortified with flaxseed cake in a dose-dependent manner. Regardless of the leavening agent, the fortification determined a decrease of n-6:n-3 ratio, reaching the recommended value (<3) already at the 7.5% level. Furthermore, under the same fortification level, sourdough breads showed a higher level of total phenols and antiradical activity than baker’s yeast breads. Sensory profiles were instead deeply influenced by both the fortification percentage and the leavening agents. In conclusion, considering both nutritional and sensory results, the best formulation as a function of leavening agent utilized was defined as 5% and 7.5% when sourdough and baker’s yeast were used, respectively.

Gluten-Free Brewing: Issues and Perspectives

Celiac disease (CD) is an immune-mediated gluten-sensitive enteropathy. Currently, it affects around 1% of world population, but it is constantly growing. Celiac patients have to follow a strict gluten-free (GF) diet. Beer is one of the most consumed beverages worldwide, but it is not safe for people with CD. It has a gluten content usually above the safe threshold (20 ppm), determined by the official method for hydrolyzed foods (R5-competitive-ELISA). The demand on the market for GF beers is increasingly growing. This review aims to provide a comprehensive overview of different strategies to produce GF beer, highlighting strengths and weaknesses of each approach and taking into account technological and sensory issues. GF cereals or pseudocereals have poor brewing attitudes (if used as main raw material) and give the beer unusual flavour. Instead, enzymatic treatments allow traditional brewing process followed by gluten content reduction. A survey on 185 GF-producing breweries (both industrial and craft) from all over the world have been considered to assess which approach is most used. Beers brewed with GF cereals and pseudocereals (used in well-balanced proportions) are more common than gluten-removed (GR) beers, obtained by enzymatic treatment.

Textural and Sensory Features Changes of Gluten Free Muffins Based on Rice Sourdough Fermented with Lactobacillus spicheri DSM 15429

Gluten free products available on the market have a low textural quality associated with high crumbly structure, low-flavor, aroma, poor mouthfeel, less appearance, in comparison with the conventional final baked products. The aim of this study was to assess the influence of rice sourdough fermented with Lactobacillus spicheri DSM 15429 strain on textural, volatile profile, and sensorial properties of gluten free muffins in order to obtain baked goods with improved quality characteristics. Lactobacillus spicheri is a novel strain isolated from industrial rice sourdough but unexploited for bakery products manufacturing. The results showed that Lactobacillus spicheri DSM 15429 was able to growth in the rice flour influencing the texture and the volatile profile of gluten free muffins as well as their sensory characteristics. Both, textural parameters and volatiles recorded significant differences comparing to muffins obtained with a spontaneously fermented rice sourdough. Hardness and cohesiveness decreased while springiness and resilience of gluten free muffins improved their values. The volatile profile of gluten free muffins was significantly improved by utilization of the rice sourdough fermented with Lactobacilus spicheri DSM 15429. 3-methylbutanal, 2-methylbutanal, acetophenone and limonene were the main volatile derivatives responsible for aroma and odor scores of sensory analysis.

Defined co-cultures of yeast and bacteria modify the aroma, crumb and sensory properties of bread

AIMS

Yeast and bacterial communities inhabit a sourdough starter to make artisanal bread. This study shows whether the interactions of micro-organisms derived from Australian sourdough starters provide some of the positive flavour, and aroma properties to bread by using defined sourdough cultures as the sole leaven in bread production.

METHODS AND RESULTS

An investigation of Australian sourdough starters found that they contained Saccharomyces cerevisiae and Kazachstania exigua yeasts. When these yeasts were inoculated alone to ferment wheat flour in an extended fermentation, the bread had a heterogeneous crumb structure, a deeper colour and a distinctive chemical aroma profile than those made with commercial baker's yeast. When bread was made combining these yeasts individually and in combinations with lactic acid bacteria also isolated from these sourdough starters, including Lactobacillus plantarum, L. brevis, L. rossiae, L. casei, the bread aroma profiles and crumb structure were more distinctive, with compounds associated with sour aromas produced, and preferred by sensory panels.

CONCLUSIONS

The use of defined mixed cultures as the leaven in bread making, by exploiting the microbial diversity of artisanal Australian starters, can produce bread with distinctive and attractive aromas.

SIGNIFICANCE AND IMPACT OF THE STUDY

Understanding and identifying the community ecosystems found in sourdough cultures and using them as the sole leaven in bread production provide novel insights into microbial interactions and how they affect food quality by removing the effects of commercial yeast strains.

Wheat Fermentation With Enterococcus mundtii QAUSD01 and Wickerhamomyces anomalus QAUWA03 Consortia Induces Concurrent Gliadin and Phytic Acid Degradation and Inhibits Gliadin Toxicity in Caco-2 Monolayers

Foods containing high amounts of either phytic acid or gliadin can pose a risk for development of iron deficiency and celiac disease, respectively. The present study was conducted to evaluate the effects of preselected gliadin degrading strains, Enterococcus mundtii QAUSD01 and Wickerhamomyces anomalus QAUWA03, on phytic acid and gliadin degradation in six wheat cultivars (Lasani 2008, Seher 2006, Chakwal 97, Shafaq 2006, Bars 2009, Barani 83). Tight junction proteins, trans-epithelial resistance (TER) and ruffle formation in Caco-2 cells were evaluated relative to Saccharomyces cerevisiae-mediated fermented and unfermented controls. Phytic acid degradation was demonstrated in all six cultivars fermented with E. mundtii QAUSD01 and W. anomalus QAUWA03 consortia. Among the six fermented cultivars, Shafaq 2006 showed relatively higher degradation of gliadin. In comparison to the other tested wheat varieties, fermentation of Lasani 2006 was associated with minimal toxic effects on Caco-2 cells in terms of ruffle formation, tight junction proteins and TER, which can be attributed to extensive degradation of toxic gliadin fragments.

Sourdough Fermentation Favorably Influences Selenium Biotransformation and the Biological Effects of Flatbread

Although selenium is of great importance for the human body, in several world regions the intake of this essential trace element does not meet the dietary reference values. To achieve optimal intake, fortification of bread by using selenium-enriched flour has been put forward. Less is known on the potential effect of sourdough fermentation, which might be worth exploring as the biological effects of selenium strongly depend on its chemical form and sourdough fermentation is known to cause transformations of nutrients and phytochemicals, including the conversion of inorganic selenium into organic selenocompounds. Here we investigated the bio transformation of selenium by sourdough fermentation in a typical Italian flatbread (piadina) made with standard (control) or selenium-enriched flour. The different piadina were submitted to in vitro digestion, and the biological activity of the resulting hydrolysates was tested by means of cultured human liver cells exposed to an exogenous oxidative stress. The use of selenium-enriched flour and sourdough fermentation increased the total content of bioaccessible selenium in organic form, compared to conventional fermentation, and led to protective effects counteracting oxidative damage in cultured cells. The present study suggests that selenium-rich, sourdough-fermented bakery products show promise for improving human selenium nutrition whenever necessary.

Flavoring Production in Kamut®, Quinoa and Wheat Doughs Fermented by Lactobacillus paracasei, Lactobacillus plantarum, and Lactobacillus brevis: A SPME-GC/MS Study

This study identified the odor-active compounds and the qualitative characteristics of doughs from “ancient” grains flours fermented by lactic acid bacteria. For this purpose doughs made with quinoa and Kamut® flours have been produced and inoculated with strains belonging to the species Lactobacillus paracasei, Lactobacillus plantarum and Lactobacillus brevis and compared with fermented doughs made from 100% wheat flour. The quality of the doughs was determined by assessment of pH, total titratable acidity, lactic acid bacteria growth and flavor compounds. The results showed that lactic acid bacteria used were able to grow in the different substrates reaching more than 9.0 log CFU/g after 24 h fermentation, although the best microbial growth was recorded in the doughs made with quinoa flour fermented with Lactobacillus paracasei I1. Good acidification and heterogeneous aromatic profile were recognized in all the doughs even if the volatile composition mainly derived from microbial specie. Among all the used strains, mostly Lactobacillus paracasei I1 positively contributed to the aromatic profile of the doughs, independently from flour type, producing the highest amount of different ketones such as, diacetyl, acetoin, 2,6-dimethyl-4-heptanone, 5-methyl-3-hexanone, 4-methyl-3-penten-2-one, volatile compounds highly appreciated in the bakery products for their buttery, fatty and fruity notes. So, the positive characteristic of Lactobacillus paracasei I1 to enhance the production of desired volatile compounds could make it suitable as adjunct culture starter in the bakery industry. Many differences in volatile organic compounds derived also by the type of flour used. Quinoa fermented doughs were characterized for specific nutty, roasted, acid and buttery tones derived from pyrazines, ketones and acid compounds whereas Kamut® fermented doughs were characterized for fruity, rose, green and sweet tones derived from aldehydes and ketones production. So, the use of quinoa and Kamut® flours opportunely fermented, as partial or complete substitution of wheat flour, may be interesting for producing more balanced bakery products with respect to nutritional aspects and to unique aromatic profile. Furthermore, the supplementation of these flours, rich in protein content and free amino acids, could represent an optimal substrate to enhance the growth of lactic acid bacteria used as starter culture in leavened bakery products.

Current Trends in Ancient Grains-Based Foodstuffs: Insights into Nutritional Aspects and Technological Applications

For centuries, ancient grains fed populations, but due to their low yield, they were abandoned and replaced by high-yielding species. However, currently, there is a renewed interest in ancient wheat and pseudocereal grains from consumers, farmers, and manufacturers. Ancient wheat such as einkorn, emmer, spelt, and Kamut®, are being reintegrated because of their low fertilizer input, high adaptability and important genetic diversity. New trends in pseudocereal products are also emerging, and they are mostly appreciated for their nutritional outcomes, particularly by the gluten-free market. Toward healthier lifestyle, ancient grains-based foodstuffs are a growing business and their industrialization is taking 2 pathways, either as a raw ingredient or a functional ingredient. This paper deals with these grain characteristics by focusing on the compositional profile and the technological potential.

Potential of Lactobacillus plantarum ccm 3627 and Lactobacillus brevis ccm 1815 for fermentation of cereal substrates

Lactobacillus is the most representative strain in a group of lactic acid bacteria, which perform an essential role in the preservation and production of wholesome foods. Lactic acid fermentation is the oldest traditional method for preparation of fermented vegetables, meat products, dairy products and cereal foods. Cereal grains are considered to be one of the most important sources of dietary proteins, carbohydrates, vitamins, minerals and fibre for people. The main exploitation of cereals is to prepare sourdough, which is a mixture of wheat, rye or other cereal flour with water and contains yeasts and lactobacilli. The basic biochemical changes that occur in sourdough bread fermentation are acidification of the dough with organic acids produced by the lactobacilli and leavening with carbon dioxide produced by the yeast and the lactobacilli. Acidification perhaps initiate enzymatic processes of proteins and phytates degradation. Lactobacilli produce various enzymes which make flavour precursors, improve of mineral bioavailability or degrade celiac active peptides, because some species of lactobacilli produce specific peptidases during growth, which are capable to hydrolyze hardly cleavable, celiac-active proline-rich peptides. Microbial fermentation with selected strains of lactobacilli may be new alternative approach for modification of gluten by hydrolysis. In this paper are described growth characteristics and intracellular aminopeptidases activities of Lactobacillus plantarum CCM 3627 and Lactobacillus brevis CCM 1815. Work was focused on characterization of the lactobacilli for potential usage as a starter culture in further fermentation experiments.