Role of tailored sourdough fermentation in the flavor of wholegrain-oat bread.

Sourdough technology has been known for its role in the improvement of texture, flavor, and quality of mainly wheat and rye-based breads for decades. However, little is reported about its use in the improvement of whole-grain oat bread, especially concerning flavor formation, which is one major consumer drivers. This study investigated the effects of sourdough obtained by different lactic acid bacteria and yeast starters consortia on the texture and flavor of 100% oat bread. Four different consortia were selected to obtain four oat sourdoughs, which were analyzed to assess the main features due to the different starter fermentation metabolism. Sourdoughs were added to breads as 30% dough weight. Bread quality was technologically monitored via hardness and volume measurements. Sourdough breads were softer and had higher specific volume. The sensory profile of sourdoughs and breads was assessed by a trained panel in sensory laboratory conditions, and the volatile profile was analyzed by HS-SPME-GC-MS. Sourdoughs were rated with higher intensities than untreated control for most of attributes, especially concerning sour aroma and flavor attributes. Sourdough breads were rated with higher intensities than control bread for sour vinegar flavor and total odor intensity, in addition they had richer volatile profile. Our results confirmed that sourdough addition can lead to an enhanced flavor, moreover, it demonstrated that the use of different consortia of lactic acid bacteria and yeast strains leads to the improvement of texture and altered sensory profile of whole-oat bread.

Fermentation Conditions Affect the Synthesis of Volatile Compounds, Dextran, and Organic Acids by Weissella confusa A16 in Faba Bean Protein Concentrate.

Fermentation with Weissella confusa A16 could improve the flavor of various plant-based sources. However, less is known about the influence of fermentation conditions on the profile of volatile compounds, dextran synthesis and acidity. The present work investigates the synthesis of potential flavor-active volatile compounds, dextran, acetic acid, and lactic acid, as well as the changes in viscosity, pH, and total titratable acidity, during fermentation of faba bean protein concentrate with W. confusa A16. A Response Surface Methodology was applied to study the effect of time, temperature, dough yield, and inoculum ratio on the aforementioned responses. Twenty-nine fermentations were carried out using a Central Composite Face design. A total of 39 volatile organic compounds were identified: 2 organic acids, 7 alcohols, 8 aldehydes, 2 alkanes, 12 esters, 3 ketones, 2 aromatic compounds, and 3 terpenes. Long fermentation time and high temperature caused the formation of ethanol and ethyl acetate and the reduction of hexanal, among other compounds linked to the beany flavor. Levels of dextran, acetic acid, and lactic acid increased with increasing temperature, time, and dough yield. Optimal points set for increased dextran and reduced acidity were found at low temperatures and high dough yield. Such conditions would result in hexanal, ethyl acetate and ethanol having a relative peak area of 35.9%, 7.4%, and 4.9%, respectively.

Flavor challenges in extruded plant-based meat alternatives: A review.

Demand for plant-based meat alternatives has increased in recent years due to concerns about health, ethics, the environment, and animal welfare. Nevertheless, the market share of plant-based meat alternatives must increase significantly if they are to support sustainable food production and consumption. Flavor is an important limiting factor of the acceptability and marketability of plant-based meat alternatives. Undesirable chemosensory perceptions, such as a beany flavor, bitter taste, and astringency, are often associated with plant proteins and products that use them. This study reviewed 276 articles to answer the following five research questions: (1) What are the volatile and nonvolatile compounds responsible for off-flavors? (2) What are the mechanisms by which these flavor compounds are generated? (3) What is the influence of thermal extrusion cooking (the primary structuring technique to transform plant proteins into fibrous products that resemble meat in texture) on the flavor characteristics of plant proteins? (4) What techniques are used in measuring the flavor properties of plant-based proteins and products? (5) What strategies can be used to reduce off-flavors and improve the sensory appeal of plant-based meat alternatives? This article comprehensively discusses, for the first time, the flavor issues of plant-based meat alternatives and the technologies available to improve flavor and, ultimately, acceptability.

How water-soluble saccharides drive the metabolism of lactic acid bacteria during fermentation of brewers' spent grain.

We proposed a novel phenomic approach to track the effect of short-term exposures of Lactiplantibacillus plantarum and Leuconostoc pseudomesenteroides to environmental pressure induced by brewers' spent grain (BSG)-derived saccharides. Water-soluble BSG-based medium (WS-BSG) was chosen as model system. The environmental pressure exerted by WS-BSG shifted the phenotypes of bacteria in species- and strains-dependent way. The metabolic drift was growth phase-dependent and likely underlay the diauxic profile of organic acids production by bacteria in response to the low availability of energy sources. Among pentosans, metabolism of arabinose was preferred by L. plantarum and xylose by Leuc. pseudomesenteroides as confirmed by the overexpression of related genes. Bayesian variance analysis showed that phenotype switching towards galactose metabolism suffered the greatest fluctuation in L. plantarum. All lactic acid bacteria strains utilized more intensively sucrose and its plant-derived isomers. Sucrose-6-phosphate activity in Leuc. pseudomesenteroides likely mediated the increased consumption of raffinose. The increased levels of some phenolic compounds suggested the involvement of 6-phospho-ß-glucosidases in ß-glucosides degradation. Expression of genes encoding ß-glucoside/cellobiose-specific EII complexes and phenotyping highlighted an increased metabolism for cellobiose. Our reconstructed metabolic network will improve the understanding of how lactic acid bacteria may transform BSG into suitable food ingredients.

Biosynthesis of γ-aminobutyric acid by lactic acid bacteria in surplus bread and its use in bread making.

AIMS: The aim of this study was to investigate the effectiveness of bread as substrate for γ-aminobutyric acid (GABA) biosynthesis, establishing a valorization strategy for surplus bread, repurposing it within the food chain. METHODS AND RESULTS: Surplus bread was fermented by lactic acid bacteria (LAB) to produce GABA. Pediococcus pentosaceus F01, Levilactobacillus brevis MRS4, Lactiplantibacillus plantarum H64 and C48 were selected among 33 LAB strains for the ability to synthesize GABA. Four fermentation experiments were set up using surplus bread as such, added of amylolytic and proteolytic enzymes, modifying the pH or mixed with wheat bran. Enzyme-treated slurries led to the release of glucose (up to 20 mg g-1 ) and free amino acid, whereas the addition of wheat bran (30% of bread weight) yielded the highest GABA content (circa 800 mg kg-1 of dry weight) and was the most suitable substrate for LAB growth. The selected slurry was ultimately used as an ingredient in bread making causing an increase in free amino acids. CONCLUSIONS: Besides the high GABA concentration (148 mg kg-1 dough), the experimental bread developed in this study was characterized by good nutritional properties, highlighting the efficacy of tailored bioprocessing technologies as means to mitigate food wastage. SIGNIFICANCE AND IMPACT OF STUDY: Our results represent a proof of concept of effective strategies to repurpose food industry side streams.

Bioprocessing of Barley and Lentil Grains to Obtain In Situ Synthesis of Exopolysaccharides and Composite Wheat Bread with Improved Texture and Health Properties.

A comprehensive study into the potential of bioprocessing techniques (sprouting and sourdough fermentation) for improving the technological and nutritional properties of wheat breads produced using barley and lentil grains was undertaken. Dextran biosynthesis in situ during fermentation of native or sprouted barley flour (B or SB) alone or by mixing SB flour with native or sprouted lentil flour (SB-L or SB-SL) by Weissella paramesenteroides SLA5, Weissella confusa SLA4, Leuconostoc pseudomesenteroides DSM 20193 or Weissella confusa DSM 20194 was assessed. The acidification and the viscosity increase during 24 h of fermentation with and without 16% sucrose (on flour weight), to promote the dextran synthesis, were followed. After the selection of the fermentation parameters, the bioprocessing was carried out by using Leuconostoc pseudomesenteroides DSM 20193 (the best LAB dextran producer, up to 2.7% of flour weight) and a mixture of SB-SL (30:70% w/w) grains, enabling also the decrease in the raffinose family oligosaccharides. Then, the SB-SL sourdoughs containing dextran or control were mixed with the wheat flour (30% of the final dough) and leavened with baker's yeast before baking. The use of dextran-containing sourdough allowed the production of bread with structural improvements, compared to the control sourdough bread. Compared to a baker's yeast bread, it also markedly reduced the predicted glycemic index, increased the soluble (1.26% of dry matter) and total fibers (3.76% of dry matter) content, giving peculiar and appreciable sensory attributes.

Bioprocessed Brewers' Spent Grain Improves Nutritional and Antioxidant Properties of Pasta.

Brewers' spent grain (BSG), the by-product of brewing, was subjected to a xylanase treatment followed by fermentation with Lactiplantibacillus plantarum PU1. Bioprocessed BSG has been used as ingredient to obtain a fortified semolina pasta which can be labeled as "high fiber" and "source of protein" according to the European Community Regulation No. 1924/2006. Compared to native BSG, the use of bioprocessed BSG led to higher protein digestibility and quality indices (essential amino acid index, biological value, protein efficiency ratio, nutritional index), as well as lower predicted glycemic index. Bioprocessing also improved the technological properties of fortified pasta. Indeed, brightfield and confocal laser scanning microscopy revealed the formation of a more homogeneous protein network, resulting from the degradation of the arabinoxylan structure of BSG, and the release of the components entrapped into the cellular compartments. The extensive cell wall disruption contributed to the release of phenols, and conferred enhanced antioxidant activity to the fortified pasta. The persistence of the activity was demonstrated after in vitro-mimicked digestion, evaluating the protective effects of the digested pasta towards induced oxidative stress in Caco-2 cells cultures. The fortified pasta showed a peculiar sensory profile, markedly improved by the pre-treatment, thus confirming the great potential of bioprocessed BSG as health-promoting food ingredient.

Sourdough fermentation of whole and sprouted lentil flours: In situ formation of dextran and effects on the nutritional, texture and sensory characteristics of white bread.

Exopolysaccharides produced in situ by lactic acid bacteria during sourdough fermentation are recognized as bread texture improvers. In this study, the suitability of whole and sprouted lentil flours, added with 25% on flour weight sucrose for dextran formation by selected strains during sourdough fermentation, was evaluated. The dextran synthesized in situ by Weissella confusa SLA4 was 9.2 and 9.7% w/w flour weight in lentil and sprouted lentil sourdoughs, respectively. Wheat bread supplemented with 30% w/w sourdough showed increased specific volume and decreased crumb hardness and staling rate, compared to the control wheat bread. Incorporation of sourdoughs improved the nutritional value of wheat bread, leading to increased total and soluble fibers content, and the aroma profile. The integrated biotechnological approach, based on sourdough fermentation and germination, is a potential clean-label strategy to obtain high-fibers content foods with tailored texture, and it can further enhance the use of legumes in novel foods.

Plant-Based Alternatives to Yogurt: State-of-the-Art and Perspectives of New Biotechnological Challenges.

Due to the increasing demand for milk alternatives, related to both health and ethical needs, plant-based yogurt-like products have been widely explored in recent years. With the main goal to obtain snacks similar to the conventional yogurt in terms of textural and sensory properties and ability to host viable lactic acid bacteria for a long-time storage, several plant-derived ingredients (e.g., cereals, pseudocereals, legumes, and fruits) as well as technological solutions (e.g., enzymatic and thermal treatments) have been investigated. The central role of fermentation in yogurt-like production led to specific selections of lactic acid bacteria strains to be used as starters to guarantee optimal textural (e.g., through the synthesis of exo-polysaccharydes), nutritional (high protein digestibility and low content of anti-nutritional compounds), and functional (synthesis of bioactive compounds) features of the products. This review provides an overview of the novel insights on fermented yogurt-like products. The state-of-the-art on the use of unconventional ingredients, traditional and innovative biotechnological processes, and the effects of fermentation on the textural, nutritional, functional, and sensory features, and the shelf life are described. The supplementation of prebiotics and probiotics and the related health effects are also reviewed.

Brewers' spent grain as substrate for dextran biosynthesis by Leuconostoc pseudomesenteroides DSM20193 and Weissella confusa A16.

BACKGROUND: Lactic acid bacteria can synthesize dextran and oligosaccharides with different functionality, depending on the strain and fermentation conditions. As natural structure-forming agent, dextran has proven useful as food additive, improving the properties of several raw materials with poor technological quality, such as cereal by-products, fiber-and protein-rich matrices, enabling their use in food applications. In this study, we assessed dextran biosynthesis in situ during fermentation of brewers´ spent grain (BSG), the main by-product of beer brewing industry, with Leuconostoc pseudomesenteroides DSM20193 and Weissella confusa A16. The starters performance and the primary metabolites formed during 24 h of fermentation with and without 4% sucrose (w/w) were followed. RESULTS: The starters showed similar growth and acidification kinetics, but different sugar utilization, especially in presence of sucrose. Viscosity increase in fermented BSG containing sucrose occurred first after 10 h, and it kept increasing until 24 h concomitantly with dextran formation. Dextran content after 24 h was approximately 1% on the total weight of the BSG. Oligosaccharides with different degree of polymerization were formed together with dextran from 10 to 24 h. Three dextransucrase genes were identified in L. pseudomesenteroides DSM20193, one of which was significantly upregulated and remained active throughout the fermentation time. One dextransucrase gene was identified in W. confusa A16 also showing a typical induction profile, with highest upregulation at 10 h. CONCLUSIONS: Selected lactic acid bacteria starters produced significant amount of dextran in brewers' spent grain while forming oligosaccharides with different degree of polymerization. Putative dextransucrase genes identified in the starters showed a typical induction profile. Formation of dextran and oligosaccharides in BSG during lactic acid bacteria fermentation can be tailored to achieve specific technological properties of this raw material, contributing to its reintegration into the food chain.

Isolation and characterization of indigenous Weissella confusa for in situ bacterial exopolysaccharides (EPS) production in chickpea sourdough.

Legume-based sourdough represents a potential ingredient for the manufacture of novel baked products. However, the lack of gluten of legume flours can restrict their use due to their poor technological properties. To overcome such issue, the in situ production of bacterial exopolysaccharides (EPS) during fermentation has been proposed. In this study, an EPS-producing lactic acid bacteria for in situ production in chickpea sourdough was isolated. After several backsloppings of the spontaneously fermented chickpea flour dough, a dominant strain of Weissella confusa was isolated and identified. W. confusa Ck15 was able to produce linear dextran with 2.6% α-(1 â†’ 3) linked branches, from sucrose. Temperature of 30 °C, dough yield of 333, and 2% of sucrose addition were used to produce fermented chickpea sourdoughs. The acidification and rheology of the sourdoughs inoculated with W. confusa Ck15, Leuconostoc pseudomesenteroides DSM 20193, as positive control, and Lactobacillus plantarum F8, as negative control, were compared. The in situ dextran production by W. confusa Ck15 fermentation led to the highest viscosity increase (5.90 Pa·s) and the highest EPS percentage in the doughs (1.49%), compared to the other doughs. The in situ dextran production represents a potential approach for improving the use of legume flour in bakery products; overall, this experiment represents a first step for the exploitation of microbial EPS for setting up a baking process for chickpea based product.

Bioprocessing of Brewers' Spent Grain Enhances Its Antioxidant Activity: Characterization of Phenolic Compounds and Bioactive Peptides.

Brewers' spent grain (BSG) is the major by-product of the brewing industry which remain largely unutilized despite its nutritional quality. In this study, the effects of fermentation on BSG antioxidant potential were analyzed. A biotechnological protocol including the use of xylanase followed by fermentation with Lactiplantibacillus plantarum (Lactobacillus plantarum) PU1, PRO17, and H46 was used. Bioprocessed BSG exhibited enhanced antioxidant potential, characterized by high radical scavenging activity, long-term inhibition of linoleic acid oxidation and protective effect toward oxidative stress on human keratinocytes NCTC 2544. Immunolabelling and confocal laser microscopy showed that xylanase caused an extensive cell wall arabinoxylan disruption, contributing to the release of bound phenols molecules, thus available to further conversion through lactic acid bacteria metabolism. To clarify the role of fermentation on the antioxidant BSG potential, phenols were selectively extracted and characterized through HPLC-MS techniques. Novel antioxidant peptides were purified and identified in the most active bioprocessed BSG.

Waste bread recycling as a baking ingredient by tailored lactic acid fermentation.

Food-grade waste and side streams should be strictly kept in food use in order to achieve sustainable food systems. At present, the baking industry creates food-grade waste as excess and deformed products that are mainly utilized for non-food uses, such as bioethanol production. The purpose of this study was therefore to explore the potential of waste wheat bread recycling for fresh wheat bread production. Waste bread recycling was assessed without further processing or after tailored fermentation with lactic acid bacteria producing either dextran or ß-glucan exopolysaccharides. When non-treated waste bread slurry was added to new bread dough, bread quality (specific volume and softness) decreased with increasing content of waste bread addition. In situ EPS-production (dextran and microbial ß-glucan) significantly increased waste bread slurry viscosity and yielded residual fructose or glucose that could effectively replace the sugar added for yeast leavening. Furthermore, fermentation acidified waste bread matrix, thus improving the hygienic safety of the process. Bread containing dextran synthesized in situ by Weissella confusa A16 showed good technological quality. The produced dextran compensated the adverse effect of recycled bread on new bread quality attributes by 12% increase in bread specific volume and 37% decrease in crumb hardness. In this study, a positive technological outcome of the bread containing microbial ß-glucan was not detected. The waste bread fermented by W. confusa A16 containing dextran appears to enable safe bread recycling with low acidity and minimal quality loss.

Co-fermentation of Propionibacterium freudenreichii and Lactobacillus brevis in Wheat Bran for in situ Production of Vitamin B12.

The present study investigated the effect of co-fermentation on vitamin B12 content and microbiological composition of wheat bran. Propionibacterium freudenreichii DSM 20271 was used as the producer of vitamin while Lactobacillus brevis ATCC 14869 was selected to ensure the microbial safety of the bran dough. Fermentation trials were conducted in bioreactors to monitor and adjust the pH of the ferments. Vitamin B12 level reached 357 ± 8 ng/g dry weight (dw) after 1 day of pH-controlled fermentation with P. freudenreichii monoculture and remained stable thereafter. In co-fermentation with L. brevis, slightly less vitamin B12 (255 ± 31 ng/g dw) was produced in 1 day and an effective inhibition of the growth of total Enterobacteriaceae and Bacillus cereus was obtained. On day 3, vitamin B12 content in pH-controlled co-fermentation increased to 332 ± 44 ng/g dw. On the other hand, without a pH control, co-fermentation resulted in a stronger inhibition of Enterobacteriaceae and B. cereus but a lower level of vitamin B12 (183 ± 5 ng/g dw on day 3). These results demonstrated that wheat bran fermented by P. freudenreichii and L. brevis can be a promising way to produce vitamin B12 fortified plant-origin food ingredients, which could reduce cereal waste streams and contribute to a more resilient food chain.

Recent Advances in the Use of Sourdough Biotechnology in Pasta Making.

The growing consumers' request for foods with well-balanced nutritional profile and functional properties promotes research on innovation in pasta making. As a staple food and a common component of diet, pasta can be considered as a vector of dietary fiber, vegetable proteins, vitamins, minerals, and functional compounds. The conventional process for pasta production does not include a fermentation step. However, novel recipes including sourdough-fermented ingredients have been recently proposed, aiming at enhancing the nutritional and functional properties of this product and at enriching commercial offerings with products with new sensorial profiles. The use of sourdough for pasta fortification has been investigated under several aspects, including fortification in vitamin B, the reduction of starch digestibility, and gluten content. Sourdough fermentation has also been successfully applied to non-conventional flours, (e.g., from pseudocereals and legumes), in which an overall increase of the nutritional value and health-promoting compounds, such as a significant decrease of antinutritional factors, were observed. Fermented non-conventional flours, obtained through spontaneous fermentation or using selected starters, have been proposed as pasta ingredients. As the result of wheat replacement, modification in textural properties of pasta may occur. Nonetheless, fermentation represents an efficient tool in improving, besides nutritional and functional profile, the sensory and technological features of fortified pasta.

Fermentation Biotechnology Applied to Cereal Industry By-Products: Nutritional and Functional Insights.

Cereals are one of the major food sources in human diet and a large quantity of by-products is generated throughout their processing chain. These by-products mostly consist of the germ and outer layers (bran), deriving from dry and wet milling of grains, brewers' spent grain originating from brewing industry, or others originating during bread-making and starch production. Cereal industry by-products are rich in nutrients, but still they end up as feed, fuel, substrates for biorefinery, or waste. The above uses, however, only provide a partial recycle. Although cereal processing industry side streams can potentially provide essential compounds for the diet, their use in food production is limited by their challenging technological properties. For this reason, the development of innovative biotechnologies is essential to upgrade these by-products, potentially leading to the design of novel and commercially competitive functional foods. Fermentation has been proven as a very feasible option to enhance the technological, sensory, and especially nutritional and functional features of the cereal industry by-products. Through the increase of minerals, phenolics and vitamins bioavailability, proteins digestibility, and the degradation of antinutritional compounds as phytic acid, fermentation can lead to improved nutritional quality of the matrix. In some cases, more compelling benefits have been discovered, such as the synthesis of bioactive compounds acting as antimicrobial, antitumoral, antioxidant agents. When used for baked-goods manufacturing, fermented cereal by-products have enhanced their nutritional profile. The key factor of a successful use of cereal by-products in food applications is the use of a proper bioprocessing technology, including fermentation with selected starters. In the journey toward a more efficient food chain, biotechnological approaches for the valorization of agricultural side streams can be considered a very valuable help.

Influence of dextran synthesized in situ on the rheological, technological and nutritional properties of whole grain pearl millet bread.

The effect of dextran produced in situ by Weissella confusa on the structure and nutrition quality of whole grain pearl millet bread containing 50% of wheat flour was investigated. NMR spectroscopy analysis indicated that the dextran formed by the strain consisted of a α-(1 → 6)-linked linear backbone and 3% α-(1 → 3) branches, and had a molar mass of 3.3 × 106 g/mol. In situ production resulted in 3.5% dextran (DW) which significantly enhanced the dough extensional properties, increased the bread specific volume (∼13%) and decreased crumb firmness (∼43%), moisture loss (∼15%) and staling rate (∼10%), compared to the control millet bread. DSC analysis showed that amylopectin recrystallization was significantly reduced in the bread containing dextran. In situ dextran production altered the nutritional value of millet, leading to increased free phenolic content (∼30%) and antioxidant activity. It also markedly lowered the bread predicted glycemic index and improved in vitro protein digestibility.