Thirty years of knowledge on sourdough fermentation: A systematic review

Molecular characterization and multifunctional evaluation of lactic acid bacteria isolated from traditional sourdough

The primary objective of this study was to characterize lactic acid bacteria (LAB) strains derived from sourdough for possible utilization as functional starters to produce sourdough and various cereal-based fermented foods. A total of 350 autochthonous LAB strains were isolated from 65 Type I sourdough samples and characterized using six random amplified polymorphic DNA (RAPD) primers at intra- and interspecific levels. Species identification of selected strains representing distinct clusters from RAPD analysis was performed based on the 16S rRNA region. The LAB strains were identified as Companilactobacillus crustorum (n = 135), Levilactobacillus brevis (n = 125), Latilactobacillus curvatus (n = 40), Companilactobacillus paralimentarius (n = 32), and Lactiplantibacillus plantarum (n = 18). A total of 66 LAB strains were selected for technological characterization along with two commercial strains. The characterization involved acidity development, EPS production potential, leavening activity, and growth abilities under harsh conditions. Principle component analysis (PCA) identified 2 Lp. plantarum and 14 Lev. brevis strains as the most relevant technologically. Among them, Lp. plantarum L35.1 and Lev. brevis L37.1 were resistant to tetracycline. Evaluation of probiotic characteristics (survival in pH 2.5 and bile presence, auto aggregation capacity, hydrophobic activity, antioxidant activity, antimicrobial activity) by PCA identified four strains with relevance to Lactobacillus rhamnosus GG (LGG), which were further selected for in vitro digestion assays. Lactiplantibacillus plantarum L7.8, Lev. brevis L55.1, and L62.2 demonstrated similar viability indices to LGG, along with increased auto aggregation capacity and antioxidant activity. These strains are promising as candidate starters for producing sourdough and sourdough-related fermented food products.

Genotypic Stability of Lactic Acid Bacteria in Industrial Rye Bread Sourdoughs Assessed by ITS-PCR Analysis

Sourdough bread production relies on metabolically active starters refreshed daily with flour and water. The stability of sourdough microbial strains is crucial for consistent bread quality. However, many bakeries lack information on the persistence of starter cultures in ongoing sourdough production. Consequently, there is growing interest in identifying microbial strains from regularly used sourdoughs that possess good functional properties and resist changes in the complex growth environment. This study aimed to evaluate the composition and stability of lactic acid bacteria (LAB) in industrial wheat (WS) and rye (RS) sourdoughs propagated over a long period. LAB isolates (n = 66) from both sourdoughs, sampled over four seasons, were identified using phenotypic methods and genotyped via ITS-PCR and ITS-PCR/TaqI restriction analysis. Eight LAB species were detected, with Lactiplantibacillus plantarum being the most dominant and stable. Nineteen distinct LAB genotypes were observed, highlighting significant diversity. The presence of identical LAB genotypes in both sourdoughs suggests microbial transfer through the environment and bakery workers. LAB in RS were found to be more stable than those in WS. These findings underscore the importance of monitoring microbial stability and diversity in industrial sourdough production to maintain consistent bread quality.

The Effects of Single- or Mixed-Strain Fermentation of Red Bean Sourdough, with or without Wheat Bran, on Bread Making Performance and Its Potential Health Benefits in Mice Model

The effects of single- (Lactobacillus fermentum) or mixed-strain (Lactobacillus fermentum, Kluyveromyces marxianus) fermentation of red bean with or without wheat bran on sourdough bread quality and nutritional aspects were investigated. The results showed that, compared to unfermented controls, the tannins, phytic acid, and trypsin inhibitor levels were significantly reduced, whereas the phytochemical (TPC, TFC, and gallic acid) and soluble dietary fiber were increased in sourdough. Meanwhile, more outstanding changes were obtained in sourdough following a mixed-strain than single-strain fermentation, which might be associated with its corresponding β-glucosidase, feruloyl esterase, and phytase activities. An increased specific volume, reduced crumb firmness, and greater sensory evaluation of bread was achieved after mixed-strain fermentation. Moreover, diets containing sourdough, especially those prepared with mixed-strain-fermented red bean with wheat bran, significantly decreased serum pro-inflammatory cytokines levels, and improved the lipid profile, HDL/LDL ratio, glucose tolerance, and insulin sensitivity of mice. Moreover, gut microbiota diversity increased towards beneficial genera (e.g., Bifidobacterium), accompanied with a greater increase in short-chain fatty acid production in mice fed on sourdough-based bread diets compared to their controls and white bread. In conclusion, mixed-strain fermentation's synergistic effect on high fiber-legume substrate improved the baking, sensory quality, and prebiotic effect of bread, leading to potential health benefits in mice.

Synthetic microbial communities: A gateway to understanding resistance, resilience, and functionality in spontaneously fermented food microbiomes

This review delves into the intricate traits of microbial communities encountered in spontaneously fermented foods (SFF), contributing to resistance, resilience, and functionality drivers. Traits of SFF microbiomes comprise of fluctuations in community composition, genetic stability, and condition-specific phenotypes. Synthetic microbial communities (SMCs) serve as a portal for mechanistic insights and strategic re-programming of microbial communities. Current literature underscores the pivotal role of microbiomes in SFF in shaping quality attributes and preserving the cultural heritage of their origin. In contrast to starter driven fermentations that tend to be more controlled but lacking the capacity to maintain or reproduce the complex flavors and intricacies found in SFF. SMCs, therefore, become indispensable tools, providing a nuanced understanding and control over fermented food microbiomes. They empower the prediction and engineering of microbial interactions and metabolic pathways with the aim of optimizing outcomes in food processing. Summarizing the current application of SMCs in fermented foods, there is still space for improvement. Challenges in achieving stability and reproducibility in SMCs are identified, stemming from non-standardized approaches. The future direction should involve embracing standardized protocols, advanced monitoring tools, and synthetic biology applications. A holistic, multi-disciplinary approach is paramount to unleashing the full potential of SMCs and fostering sustainable and innovative applications in fermented food systems.

Sourdough powder: physicochemical, microbiological properties and shelf-life stability in different package type

This study aims to optimize the culture condition of semi-liquid sourdough using Kombucha as a starter culture and to evaluate the physicochemical properties, microbial viability and recovering ability of sourdough powder when packaged in different types of packaging for 120 days. Optimal maturation time (103.47 h) and maximum leavening rate (1.27 mL/h) of sourdough were achieved at an incubation temperature of 34 °C and interval refreshment time at 7 h. The optimized culture was spray-dried using 3% Arabic gum (w/v) as a carrier agent yielding 35.86% powder with acceptable viability of 8.71 log CFU/g lactic acid bacteria and 9.03 CFU/g yeast. The sourdough powder was packed in four packaging (LDPE, vacuumed LDPE, aluminum foil laminated pouch and vacuumed aluminum foil laminated pouch) and exhibited comparable physicochemical properties during 120 days of storage. The viability of both lactic acid bacteria and yeast count in sourdough powder when packed in vacuumed aluminum foil laminated pouch showed higher stability for 90 days (6.18 log CFU/g and 6.82 log CFU/g) but reduced to below detection limit after 120 days (5.54 and 5.94 log CFU/g). This suggested that Kombucha sourdough powder packed in vacuumed aluminum laminated pouch could be stored for up to 90 days.

Functional Characterization of Different Fructilactobacillus sanfranciscensis Strains Isolated from Chinese Traditional Sourdoughs

Fructilactobacillus sanfranciscensis, the dominant species of lactic acid bacteria in sourdoughs, impacts the microstructure and flavor of steamed bread through exopolysaccharide production, acidification, proteolysis, and volatile compound generation. The aim of this study is to investigate the phenotypic diversity and technological traits of 28 F. sanfranciscensis strains of different genotypes isolated from Chinese traditional sourdoughs. The results showed that F. sanfranciscensis strains exhibited substantial variation in proteinase and peptidase activities and the amount of acidification and volatiles in fermented sourdoughs. However, we observed no significant differences in exopolysaccharide production among the strains. The strains Sx14 and Ts1 were further chosen for transcriptomics to gain a deep insight into their intraspecies diversity in sourdough fermentation. Significant transcriptome differentiations between these two strains after 12 h fermentation in sourdoughs were revealed. According to the results, the strain Sx14 possessed higher dipeptidase and aminopeptidase activities, galactose utilization, and lactic and acetic acid production abilities, whereas Ts1 showed higher transmembrane transport of substrates and fructose utilization.

Consumption of a Sourdough-Leavened Croissant Enriched with a Blend of Fibers Influences Fasting Blood Glucose in a Randomized Controlled Trial in Healthy Subjects

BACKGROUND

An incorrect lifestyle, including diet, is responsible for the worldwide dramatic increase in obesity and type 2 diabetes. Increasing dietary fiber consumption may lead to health benefits, and reformulation of bakery products may be a strategy to globally improve the diet.

OBJECTIVES

This study aimed to assess the impact of a 2-wk breakfast consumption with a sourdough-leavened croissant containing a blend of dietary fiber from 10 sources (4.8 g/100 g, croissant enriched with dietary fibers [FIBCRO]), compared with a control croissant (dietary fibers 1.3 g/100 g, CONCRO) on daily energy intake, appetite, metabolic variables, and the gut microbiome.

METHODS

Thirty-two healthy participants were randomly allocated to 2 groups consuming FIBCRO or CONCRO. Participants self-recorded their diet and appetite through 7-d weighted food diaries and visual analog scales every day over the 2 wk. At baseline and after the intervention, fasting blood and urine samples, and fecal samples were collected beside blood pressure, anthropometry, and body composition. Serum glucose, lipids, C-reactive protein, and insulin according to the official methods and serum dipeptidyl peptidase-4 (DPPIV) activity by photometric method were measured. Polyphenols and urolithins in urines were analyzed by Liquid chromatography-tandem mass spectrometry (LC/MS/MS), whereas gut microbiome in feces by shotgun metagenomics.

RESULTS

FIBCRO consumption improved fasting blood glucose compared with CONCRO (mean changes from baseline -2.0 mg/dL in FIBCRO compared with +3.1 mg/dL in CONCRO, P = 0.022), also reducing serum DPPIV activity by 1.7 IU/L (P = 0.01) and increasing urinary excretion of urolithin A-sulfate by 6.9 ng/mg creatinine (P = 0.04) compared with baseline. No further changes in any of the monitored variables or in the gut microbiome were detected.

CONCLUSIONS

Results suggested that a 2-wk consumption of a sourdough croissant claimed as "source of dietary fiber" improved fasting glycemia compared with a conventional sourdough croissant in healthy subjects. The reduced serum DPPIV activity and increased bioavailability of urolithin likely contributed to determine that effect independently from gut microbiome changes. This trial was registered at clinicaltrials.gov as NCT04999280.

Effects of acidification by traditional Jiaozi starter and neutralization with alkali (Na2CO3) on whole wheat dough properties

BACKGROUND

Whole wheat steamed bread has been recommended for its potential nutritional benefits to human health. Given the positive role of both organic acid and alkali in improving dough development and product quality, the present study investigated the effects of neutralization by addition of alkali (Na2CO3) after dough acidification with traditional Jiaozi starter on the properties of whole wheat dough.

RESULTS

The population of yeast and lactic acid bacteria and the acidification level of the dough increased significantly after fermentation with Jiaozi. Incorporation of alkali greatly improved the leavening capacity of the remixed dough and the quality of steamed bread. Jiaozi fermentation and alkali addition changed the water distribution patterns (T2) and affected the secondary structures of gluten protein, starch crystallinity and pasting properties. The storage modulus (G') of the dough increased significantly with the alkali addition, which could be attributed to the promoted cross-linking of the gluten structure and the altered hydration state of the macromolecules.

CONCLUSION

The results of the present study indicate that a combination of Jiaozi fermentation and alkali addition could improve the technological properties of whole wheat dough and the quality of steamed bread. The results will help us to further explore the potential application of moderate acidification and alkali addition in the production of leavened whole wheat products. © 2024 Society of Chemical Industry.

Effects of Wickerhamomyces anomalus Co-Fermented with Saccharomyces cerevisiae on Volatile Flavor Profiles during Steamed Bread Making Using Electronic Nose and HS-SPME-GC-MS

Steamed bread is a traditional staple food in China, and it has gradually become loved by people all over the world because of its healthy production methods. With the improvement in people's living standards, the light flavor of steamed bread fermented by single yeast cannot meet people's needs. Multi-strain co-fermentation is a feasible way to improve the flavor of steamed bread. Here, the dynamic change profiles of volatile substances in steamed bread co-fermented by Saccharomyces cerevisiae SQJ20 and Wickerhamomyces anomalus GZJ2 were analyzed using the electronic nose (E-nose) and headspace solid-phase microextraction combined with gas chromatography-mass spectrometry (HS-SPME-GC-MS). The five detectors of the E-nose rapidly detected the changes in volatile substances in different dough or steamed bread with the highest response value in co-fermented dough. A total of 236 volatile substances were detected in all the samples using HS-SPME-GC-MS, and alcohols were the most variable component, especially Phenylethyl alcohol. Significantly, more alcohols and esters were upregulated in co-fermented dough, and the addition of W. anomalus GZJ2 improved the key volatile aroma compounds of steamed bread using the relative odor activity value method (ROAV), especially the aldehydes and alcohols. Moreover, these key volatile aroma compounds can be quickly distinguished using the W2S detector of the E-nose, which can be used for the rapid detection of aroma components in steamed bread.

Type III sourdough: Evaluation of biopreservative potential in bakery products with enhanced antifungal activity

The potential biopreservative role of a Type III sourdough (tIII-SD), produced by starter cultures of Fructilactobacillus sanfranciscensis and Lactiplantibacillus plantarum ATCC 8014, was assessed for its antifungal activity in baking applications. Fermentation was carried out using different substrates to enhance the production of antifungal metabolites for 24 and 48 h. The tIII-SD samples were analyzed in relation to pH, total titratable acidity (TTA) and the production of organic acids. The water/salt-soluble extract of the tIII-SD was evaluated in relation to the inhibition potential against key fungi that contaminate bakery products including Penicillium roqueforti, Penicillium chrysogenum and Aspergillus niger. Finally, breads with 10 % of the tIII-SD were prepared and the fungi contamination was evaluated throughout the shelf life period. The lowest pH value in sourdough was obtained from 48-hour fermentation by L. plantarum. The saline extracts exhibited varying degrees of inhibition in the in vitro test; however, the greatest enhancement of this effect was obtained when whole wheat grain flour was used. The tIII-SD crafted from a blend of wheat and flaxseed flours and fermented with F. sanfranciscensis for 48 h (BSWF48h-FS), demonstrated superior performance compared to other formulations. This variant exhibited a total shelf life of 10 days, suggesting that the utilization of tIII-SD could serve as a viable alternative for natural antifungal agents, proving beneficial for the bakery industry.

Postbiotics in the Bakery Products: Applications and Nutritional Values

In recent years, the consumption of postbiotics has gained significant attention due to their potential health benefits. However, their application in the bakery industry remains underutilized. This review focuses on recent advances in the use of postbiotics, specifically the metabolites of lactic acid bacteria, in bakery products. We provide a concise overview of the multifaceted benefits of postbiotics, including their role as natural antioxidants, antimicrobials, and preservatives, and their potential to enhance product quality, extend shelf-life, and contribute to consumer welfare. This review combines information from various sources to provide a comprehensive update on recent advances in the role of postbiotics in bakery products, subsequently discussing the concept of sourdough as a leavening agent and its role in improving the nutritional profile of bakery products. We highlighted the positive effects of postbiotics on bakery items, such as improved texture, flavor, and shelf life, as well as their potential to contribute to overall health through their antioxidant properties and their impact on gut health. Overall, this review emphasizes the promising potential of postbiotics to revolutionize the bakery industry and promote healthier and more sustainable food options. The integration of postbiotics into bakery products represents a promising frontier and offers innovative possibilities to increase product quality, reduce food waste, and improve consumer health. Further research into refining techniques to incorporate postbiotics into bakery products is essential for advancing the health benefits and eco-friendly nature of these vital food items.

Impact of Sourdough from a Commercial Starter Culture on Quality Characteristics and Shelf Life of Gluten-Free Rice Breads Supplemented with Chickpea Flour

This study aimed to develop a novel gluten-free bread using a rice/chickpea flour-based sourdough, fermented by a commercial starter culture, to improve the quality characteristics and shelf life of this product. The effects of sourdough incorporation, chickpea flour content (6.5 and 10.0%), and added water level (80-110%) on batter rheology and bread quality were investigated; bread textural characteristics upon storage (0-2 days) were also monitored. The level of added water was the primary factor influencing batter rheology, as evaluated by the back extrusion test. Sourdough incorporation decreased the pH and increased the acidity of batters and breads. The inclusion of sourdough, the water level, and the storage time affected the moisture and texture parameters of the bread crumb. Sourdough incorporation into bread formulations decreased crumb hardness and staling rate and increased loaf specific volume. Moreover, intermediate water (90 and 100%) and high chickpea (10%) levels in the batters increased loaf specific volumes and crust redness, respectively. Sensory analysis revealed that sourdough-enriched breads were preferred by the assessors concerning general appearance and crumb texture. Overall, bread formulations with the incorporation of sourdough, at a 90% level of added water in the batter mixtures, exhibited the most desirable characteristics according to both instrumental and sensory analyses.

Sourdough Bread Quality: Facts and Factors

The term "sourdough" denotes a dough composed of flour and water, fermented through the action of yeast and lactic acid bacteria. The utilization of sourdough fermentation technology can enhance the nutritional attributes of bread made from wheat grain. In recent times, sourdough bread has experienced a resurgence, fueled by growing consumer demand for healthier bread options. The market dynamics for sourdough illustrate its rapid expansion and significant role in the contemporary food industry. Sourdough fermentation improves nutritional qualities by altering the structure and function of proteins and starch, enhancing dietary fiber, volatile compound profiles, and antioxidant activity, and reducing FODMAPs. The quality of sourdough bread is influenced by several factors, including fermentation environment, flour particle size, protein quality, starch characteristics, and dietary fiber composition. Moreover, the incorporation of alternative grains (intermediate wheatgrass and legume flour) and non-flour ingredients (fruits, herbs, and dairy products) presents opportunities for creating sourdough bread with unique sensory and nutritional profiles. This review offers updated insights on the quality aspects of sourdough fermentation, the factors that influence the effectiveness of the sourdough fermentation process, sourdough technology with unconventional and non-flour ingredients, and the potential market for frozen sourdough, considering its convenience and extended shelf life.

Nutritional composition, in vitro carbohydrates digestibility, textural and sensory characteristics of bread as affected by ancient wheat flour type and sourdough fermentation time

This study aimed to investigate the effect of ancient wheat flour type and sourdough fermentation time on the nutritional, textural and sensorial properties of fiber-rich sourdough bread. The proximate composition, minerals, carbohydrates, organic acids, volatiles, total phenolic content, simulated gastrointestinal digestion, textural and sensorial characteristics were investigated. Bread's minerals, total phenolics, cellulose contents and radical scavenging activity variations clearly indicates an increasing trend with sourdoughs fermentation time. Compared to maltose and glucose, fructose was predominant in all bread samples. Sourdough fermentation time and wheat type had non-significant influence on fructose content from digested fraction. Excepting emmer bread, fermentation time increased in vitro digestibility values for tested samples. The crumb textural parameters (hardness, gumminess, chewiness, cohesiveness and springiness index) were positively influenced by fermentation time. The specific clustering of the analysed characteristics distinguished emmer bread from other samples in terms of volatile compounds, textural and overall acceptability, being preferred by panellists.

Exploring the Effects of Freeze-Dried Sourdoughs with Lactiplantibacillus pentosus 129 and Limosilactobacillus fermentum 139 on the Quality of Long-Fermentation Bread

Sourdough production is a complex fermentation process. Natural sourdough fermentation without standardization causes great variability in microbial communities and derived products. Starter cultures have emerged as alternatives to natural fermentation processes, which could improve bakery quality and produce bioactive compounds. This study aimed to evaluate the impacts of freeze-drying on the production and viability of sourdoughs with Lactiplantibacillus pentosus 129 (Lp) and Limosilactobacillus fermentum 139 (Lf), as well as their effects on the quality of long-fermentation bread. These strains were selected based on their better performance considering acidification and exopolysaccharide production capacity. Sourdough with Lp and Lf were propagated until the 10th day, when physicochemical and microbiological parameters were determined. The produced sourdoughs were freeze-dried, and bread samples were produced. The freeze-drying process resulted in high survival rates and few impacts on the metabolic activity of Lp and Lf until 60 days of storage. Incorporating Lp and Lf improved the microbiological and physicochemical properties of sourdough and long-fermentation breads. Tested freeze-dried sourdoughs led to reduced bread aging (higher specific volume and decreased starch retrogradation) and increased digestibility. The results show the potential of the freeze-dried sourdoughs produced with Lp and Lf as innovative strategies for standardizing production protocols for the bakery industry, especially for producing long-term fermentation bread.

Influence of baking time and formulation of part-baked wheat sourdough bread on the physical characteristics, sensory quality, glycaemic index and appetite sensations

Raw materials and process parameters in bread production can modulate the glycemic index, which on itself has been linked with provision of better hunger satisfaction and maintaining better satiation. The objective of this research was to investigate if using unrefined wheat flour or the addition of intact cereals in formulation or alternating the baking time would have an effect on physical characteristics, sensory quality, glycaemic index and appetite sensations in wheat sourdough bread. In the study, three types of commercial part-baked frozen sourdough bread, baked to the final baking for two different times (long and short baking time) were used. A randomized controlled crossover trial was performed with 10 healthy adults who consumed sufficient quantity of bread to ingest 50 g available carbohydrates. Participants self-reported appetite sensations (desire to eat, hunger, fullness, satisfaction, appetite) on a 10 cm visual analog scale (VAS) scale in a course of 180 min. In addition, bread products were subjected to overall acceptability and different sensory attributes were examined on JAR "just about right" scale. Different bread formulations (refined flour, unrefined wheat flour, cereal flour or intact cereals) and different length of baking time significantly influenced (p < 0.005) physical, textural and sensory features of products. The alternation of aforementioned parameters decreased the glycemic index, but not significantly (p > 0.005). No correlation was found between lower GI, satiety and satiation. Liking score and incremental area under the curve (iAUC) of satiety and satiation were calculated as highest in sourdough bread with added cereals.

Bioprospecting of sourdough microbial species from artisan bakeries in the city of Valencia

This work describes the characterization of an artisanal sourdough set of bakeries located in the city of Valencia. Culture-dependent and -independent analyses detected Fructilactobacillus sanfranciscensis, Saccharomyces cerevisiae and Kazachstania humilis as dominant species. Nevertheless, specific technological parameters, including backslopping temperature, dough yield, or the addition of salt affected microbial counting, LAB/Yeast ratio, and gassing performance, favouring the appearance of several species of Lactobacillus sp., Limosilactobacillus pontis or Torulaspora delbrueckii as additional players. Sourdough leavening activity was affected positively by yeast counts and negatively by the presence of salt. In addition, the predominance of a particular yeast species appeared to impact the dynamics of CO2 release. Seven important flavour-active compounds (ethyl acetate, 1-hexanol, 2-penthylfuran, 3-ethyl-2-methyl-1,3-hexadiene, 2-octen-1-ol, nonanal and 1-nonanol) were detected in all samples and together with 3-methyl butanol and hexyl acetate represented more than the 53% of volatile abundancy in nine of the ten sourdoughs analysed. Even so, the specific microbial composition of each sample influenced the volatile profile. For example, the occurrence of K. humilis or S. cerevisiae as dominant yeast influenced the composition of major alcohol species, while F. sanfranciscensis and L. pontis positively correlated with aldehydes and octanoic acid content. In addition, relevant correlations could be also found among different technological parameters and between these, volatile compounds and microbial species. Overall, our study emphasises on how differences in technological parameters generate biodiversity in a relatively small set of artisan sourdoughs providing opportunities for excellence and quality baking products.

Wheat Sourdough Breadmaking: A Scoping Review

Using sourdough in breadmaking can enhance bread's shelf-life and flavor compared to exclusive baker's yeast use and is believed to increase its nutritional quality and healthiness. Previous research established insight into the microbial ecology of sourdough, but the link between leavening agent use, processing, and bread quality remains elusive. However, such knowledge is key for standardization, research on the health benefits, and the definition of sourdough bread. In this systematic scoping review, we analyzed 253 studies and identified large variations in the type and amount of leavening agent, fermentation conditions, and bread quality (specific loaf volume and acidification). The interrelation between these elements and their effect on the extent of fermentation is discussed, together with issues preventing proper comparison of breadmaking procedures. With this review, we want to contribute to the dialogue concerning the definition of sourdough-type bread products and the research into the health benefits attributed to them.

Wholegrain triticale sourdough: Effects of triticale:Wheat flour ratio and hydration level on bread quality

Triticale (×Triticosecale) is a hybrid between wheat (Triticum spp.) and rye (Secale cereale), producing higher grain yields than wheat in challenging environments. Triticale grain is also highly nutritious. Thus, the potential of triticale grain for an expanded range of food applications should be explored. Sourdough bread has unique functional and nutritional properties, but understanding the effects of partial substitution of triticale for wheat flour and varying levels of dough moisture content on sourdough quality requires further research. The aim of this study was to evaluate the wholegrain flour of contrasting triticale cultivars in comparison to that of a common wheat cultivar in commercial sourdough breadmaking. Two triticale cultivars (Goanna and Hawkeye, selected from a panel of Australian genotypes) and one wheat cultivar (Scout) were grown in a field trial in northern NSW, Australia. Differences in quantitative texture and color parameters of the dough and sourdough bread resulting from (1) substitution of commercial wholemeal wheat flour with different proportions of wholegrain triticale or wholegrain wheat (Scout) flour (0%, 60%, 70%, 80%, and 90%) and (2) varying the amount of water included in the dough preparation (70%, 80%, 90%, and 100 g water/100 g flour) were determined. Replacement of wholemeal wheat flour with 60% wholegrain Goanna flour (protein content 12.76%; c.f. 11.50% for Hawkeye, 12.40% for Scout), and addition of 100 g water/100 g flour in the dough preparation gave the highest quality sourdough bread based on specific volume, texture, and color parameters and had similar properties to the control made from wheat alone.

Exploring the Nutritional Impact of Sourdough Fermentation: Its Mechanisms and Functional Potential

Sourdough fermentation is one of the oldest traditional methods in food technology and occurs as a result of fermentation of flour prepared from grains. The nutritional role of sourdough is related to the final composition of fermented foods prepared through sourdough fermentation, and recently, sourdough has become an important application to improve nutrition characteristics of bread. Thanks to lactic acid bacteria (LAB) presented in sourdough microflora and metabolites partially produced by yeasts, technological and important nutritional features of the bread improve and an increase in shelf life is achieved. In addition, sourdough bread has a low glycemic index value, high protein digestibility, high mineral and antioxidant content, and improved dietary fiber composition, making it more attractive for human nutrition compared to regular bread. When the sourdough process is applied, the chemical and physical properties of fibers vary according to the degree of fermentation, revealing the physiological importance of dietary fiber and its importance to humans' large intestine microbiota. Therefore, taking these approach frameworks into consideration, this review highlights the benefits of sourdough fermentation in increasing nutrient availability and contributing positively to support human health.

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.

Competitive fungal commensalism mitigates candidiasis pathology

The mycobiota are a critical part of the gut microbiome, but host-fungal interactions and specific functional contributions of commensal fungi to host fitness remain incompletely understood. Here, we report the identification of a new fungal commensal, Kazachstania heterogenica var. weizmannii, isolated from murine intestines. K. weizmannii exposure prevented Candida albicans colonization and significantly reduced the commensal C. albicans burden in colonized animals. Following immunosuppression of C. albicans colonized mice, competitive fungal commensalism thereby mitigated fatal candidiasis. Metagenome analysis revealed K. heterogenica or K. weizmannii presence among human commensals. Our results reveal competitive fungal commensalism within the intestinal microbiota, independent of bacteria and immune responses, that could bear potential therapeutic value for the management of C. albicans-mediated diseases.

Minimal influence of milling technique in contrast to sourdough on the nutritional and organoleptic quality of bread

A number of studies have shown the effect of cereals and sourdough on bread nutritional and organoleptic quality, but the impact of the milling technique remains little studied. There are two main types of milling technic depending on the bread-making food chain. Industrial bakeries mainly use roller mills while artisanal bakeries may also use stone mill. We set up a participatory experiment with six millers and four bakers to study the impact of these two milling techniques on the quality of flours, sourdough microbiota and the quality of breads. Millers made twenty-two different flours from four different wheat grain varieties using either roller or stone mills. Each baker initiated and maintained sourdoughs with three roller-milled and three stone-milled flours during at least 32 backsloppings and then made bread. The analysis of flours revealed a typical granulometry profile linked to wheat hardness with higher particle sizes for stone-milled flours. Stone-milled flours also had a higher maltose content. However, the milling technic did not drive the composition of the sourdough microbiota. Moreover, the analysis of bread revealed that variation in bread protein fractions and in bread aroma compounds were more related to the specific baker microbial community than to the milling technique. Carbohydrate contents were clearly linked to the main LAB species metabolism. These results revealed that the sourdough microbial community shapes the organoleptic and nutritional quality of bread more than milling techniques.

Raw material-dependent changes in bacterial and compositional profiles are involved in insufficient pH decrease in natural lactic fermentation of Brassica rapa leaves

Sunki is an unsalted lactic fermented pickle made from red turnip leaves in the Kiso district, Japan. Accidental insufficient decrease in pH during sunki fermentation seriously reduces the product quality. To obtain insights into how the insufficient decrease occurs, we comprehensively analyzed differences in the microbiological and chemical properties of sunki made from three different turnip harvests and found a significant difference in their final pH. Microbiota and metabolome analyses revealed that the insufficient pH decrease showed strong relationships with the chemical composition (low lactic acid and high ammonia levels) and bacterial community structure (low Lactobacillus and high Limosilactobacillus). In vitro sunki fermentation experiments demonstrated that accumulated ammonia was associated with a decrease in glutamine and an increase in glutamic acid. Limosilactobacillus reuteri, a species of lactic acid bacteria possessing heterolactic metabolism, was suggested to be mainly responsible for insufficient decrease in pH related to accumulated ammonia during sunki fermentation.

A review of the effects of fermentation on the structure, properties, and application of cereal starch in foods

Fermentation is one of the oldest food processing techniques known to humans and cereal fermentation is still widely used to create many types of foods and beverages. Starch is a major component of cereals and the changes in its structure and function during fermentation are of great importance for scientific research and industrial applications. This review summarizes the preparation of fermented cereals and the effects of fermentation on the structure, properties, and application of cereal starch in foods. The most important factors influencing cereal fermentation are pretreatment, starter culture, and fermentation conditions. Fermentation preferentially hydrolyzes the amorphous regions of starch and fermented starches have a coarser appearance and a smaller molecular weight. In addition, fermentation increases the starch gelatinization temperature and enthalpy and reduces the setback viscosity. This means that fermentation leads to a more stable and retrogradation-resistant structure, which could expand its application in products prone to staling during storage. Furthermore, fermented cereals have potential health benefits. This review may have important implications for the modulation of the quality and nutritional value of starch-based foods through fermentation.

Expression and characterization of β-1,3-1,4-glucanase of Aspergillus usamii in Escherichia coli and its application in sourdough bread making

A β-1,3-1,4-glucanase gene (Auglu12A) from Aspergillus usamii was successfully expressed in Escherichia coli BL21(DE3). The recombinant enzyme, reAuglu12A was efficiently purified using the one-step nickel-nitrilotriacetic acid affinity chromatography. The specific activity of reAuglu12A was 694.8 U/mg, with an optimal temperature of 55°C and pH of 5.0. The reAuglu12A exhibited stability at temperatures up to 60°C and within the pH range of 4.0-5.5. The reAuglu12A hydrolytic activity was increased in the presence of metal ions, especially K+ and Na+ , whereas it exhibited a Km and Vmax of 8.35 mg/mL and 1254.02 µmol/min/mg, respectively, toward barley β-glucan at pH 5.0 and 55°C. The addition of reAuglu12A significantly increased the specific volume (p < 0.05) and reduced crumb firmness and chewiness (p < 0.05) of wheat-barley sourdough bread during a 7-day storage period compared to the control. Overall, the quality of wheat-barley sourdough bread was improved after incorporation of reAuglu12A (especially at 3000 U/300 g). These changes were attributed to the synergistic effect of acidification by sourdough and its metabolites which provided a conducive environment for the optimal action of reAuglu12A in the degradation of β-glucans of barley flour in sourdough. This stabilized the dough structure, thereby enhancing the quality, texture, and shelf life of the bread. These findings suggest that reAuglu12A holds promise as a candidate for β-glucanase application in the baking industry.

Sourdough starter culture microbiomes influence physical and chemical properties of wheat bread

Sourdough fermentation is an ancient leavening method that uses wild yeasts to produce carbon dioxide, contributing to bread rise, and bacteria which produce organic acids. Sourdough starter cultures are known to be diverse in terms of the microorganisms they comprise and while specific genera and species of microorganisms have been identified from starters and associated with specific attributes, overarching relationships between sourdough starter culture microbiomes and bread quality are not well understood. The objective of this study was to characterize differences in the physical and chemical properties of breads produced with sourdough starter cultures with unique microbiomes. Sourdough starter cultures (n = 20) of known microbial populations were used to produce wheat-based dough and bread, which were analyzed for chemical and physical properties then compared to their microbial populations in order to identify relationships between microbial profiles and dough/bread qualities. All samples were also compared to bread produced only with Saccharomyces cerevisiae (baker's yeast). Significant differences among pH, titratable acidity, loaf volume, crumb firmness, crust color, free amino acids, and organic acids were observed when comparing sourdough breads to the yeast-only control (p ≤ 0.05). Furthermore, bacterial diversity of sourdough starter cultures was correlated with lactic acid and free amino acid in the dough and loaf volume and crumb firmness of baked breads. No significant correlations were found between fungal diversity and measured outcomes. These data demonstrate the importance of considering sourdough starter microbiomes as an ingredient in baked goods and they contribute to quality and safety outcomes in bread production. PRACTICAL APPLICATION: Sourdough starter cultures have diverse and dynamic populations of bacteria and yeasts, which contribute to the production of bread products. These populations can influence the physical and chemical properties of sourdough fermentation and final breads. Understanding of the relationship between sourdough starter microbiomes and bread quality parameters can lead to targeted development of sourdough bread products with specific physical and chemical properties.

Assessment of Sourdough Fermentation Impact on the Antioxidant and Anti-Inflammatory Potential of Pearl Millet from Burkina Faso

Millet, a gluten-free cereal, has received attention for its environmental friendliness and higher protein content than other grains. It represents a staple food in many African countries, where fermentation is traditionally used for preserving food products and preparing different cereal-based products. This study aimed to assess the impact of sourdough fermentation on bioactive compounds and antioxidant and anti-inflammatory properties of pearl millet from Burkina Faso. Phenolic compounds were investigated spectrophotometrically and by HPLC-DAD. The antioxidant activity of unfermented (MF) and fermented (FeMF) millet was evaluated in vitro by spectrophotometric and fluorometric assays and ex vivo on oxidized human erythrocytes for hemolysis inhibition. Finally, the potential anti-inflammatory effect of FeMF and MF was evaluated on human adenocarcinoma cell line (HT-29) exposed to TNF-α inflammatory stimulus. Results revealed significantly higher levels of polyphenols, flavonoids, and in vitro antioxidant activity following millet fermentation. Notable differences in phenolic composition between FeMF and MF are observed, with fermentation facilitating the release of bioactive compounds such as gallic acid, quercetin, and rutin. A dose-dependent protection against oxidative hemolysis was observed in both FeMF- and MF-pretreated erythrocytes. Similarly, pretreatment with FeMF significantly reduced the levels of inflammatory markers in TNF-α-treated cells, with effects comparable to those of MF. Fermentation with sourdough represents a simple and low-cost method to improve the bioactive compounds content and in vitro antioxidant activity of millet flour with promising nutraceutical potential.

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.

Various cold storage-backslopping cycles show the robustness of Limosilactobacillus fermentum IMDO 130101 as starter culture for Type 3 sourdough production

Type 3 sourdoughs, which are starter culture-initiated and subsequently backslopped, are less studied than other sourdough types. Yet, they can serve as a model to assess how competitive starter culture strains for sourdough production are and how the microbial composition of such sourdoughs may evolve over time. In the present study, Limosilactobacillus fermentum IMDO 130101 was used to produce Type 3 sourdoughs, prepared from wheat and wholemeal wheat flours. Therefore, an initial fermentation of the flour-water mixture was performed at 30 °C for 48 h. This was followed by cold storage-backslopping cycles, consisting of refreshments (50 %, v/v), fermentation steps of 16 h, and storage at 4 °C each week, every three weeks, and every six weeks. The microbial dynamics (culture-dependent and -independent approaches) and metabolite dynamics were measured. In all sourdoughs produced, starter culture strain monitoring, following an amplicon sequence variant approach, showed that Liml. fermentum IMDO 130101 prevailed during one month when the sourdoughs were refreshed each week, during 24 weeks when the sourdoughs were refreshed every three weeks, and during 12 weeks when the sourdoughs were refreshed every six weeks. This suggested the competitiveness and robustness of Liml. fermentum IMDO 130101 for a considerable duration but also showed that the strain is prone to microbial interference. For instance, Levilactobacillus brevis and Pediococcus spp. prevailed upon further cold storage and backslopping. Also, although no yeasts were inoculated into the flour-water mixtures, Kazachstania unispora, Torulaspora delbrueckii, and Wickerhamomyces anomalus were the main yeast species found. They appeared after several weeks of storage and backslopping, which however indicated the importance of an interplay between LAB and yeast species in sourdoughs. The main differences among the mature sourdoughs obtained could be explained by the different flours used, the refreshment conditions applied, and the sampling time (before and after backslopping). Finally, the metabolite quantifications revealed continued metabolite production during the cold storage periods, which may impact the sourdough properties and those of the breads made thereof.

Tailor-made fermentation of sourdough reduces the acrylamide content in rye crispbread and improves its sensory and nutritional characteristics

Thirty strains of lactic acid bacteria (LAB) and Saccharomyces cerevisiae E8.9 (wild type) were used to formulate fifteen combinations of starters by mixing two or three LAB with the yeast (ratio LAB: yeast, 10: 1). Such combinations were used to prepare rye sourdough and their performance in term of acidification and biochemical characteristics during fermentation at two temperatures (30 and 37 °C) and duration (4 and 8 h) were screened. The best thirteen sourdough formulations were selected and used for rye crispbread making. The analysis of acrylamide concentration demonstrated that 11 out 13 formulations resulted in significant decreases of concentration compared to the baker's yeast (control), with reductions up to 79.6 %. The rye sourdough crispbreads showed also higher amount of volatile organic compounds (VOCs) compared to the baker's yeast control. Two rye sourdough crispbreads, selected to represent the opposite extremes within the thirteen formulations in term of VOC profiles and fermentation performances, demonstrated better sensory and nutritional features, such as phytic acid reduction (up to 47.3 %), and enhanced total free amino acid compared to the control. These evidences suggest the potential of tailored sourdough fermentations as alternative and suitable biotechnological strategy for lowering acrylamide levels in rye crispbread.

The quest for the perfect loaf of sourdough bread continues: Novel developments for selection of sourdough starter cultures

Sourdough fermentation, one of the oldest unit operations in food production, is currently experiencing a revival in bread production at the household, artisanal, and the industrial level. The expanding use of sourdough fermentation in bread production and the adaptation of fermentation to large scale industrial bread production also necessitate the development of novel starter cultures. Developments in the last years also have expanded the tools that are used to assess the metabolic potential of specific strains, species or genera of the Lactobacillaceae and have identified multiple ecological and metabolic traits as clade-specific. This review aims to provide an overview on the clade-specific metabolic potential of members of the Lactobacillaceae for use in sourdough baking, and the impact of these clade-specific traits on bread quality. Emphasis is placed on carbohydrate metabolism, including the conversion of sucrose and starch to soluble polysaccharides, conversion of amino acids, and the metabolism of organic acids. The current state of knowledge to compose multi-strain starter cultures (synthetic microbial communities) that are suitable for back-slopping will also be discussed. Taken together, the communication outlines the current tools for selection of microbes for use in sourdough baking.

Microbial Pigments: Major Groups and Industrial Applications

Microbial pigments have many structures and functions with excellent characteristics, such as being biodegradable, non-toxic, and ecologically friendly, constituting an important source of pigments. Industrial production presents a bottleneck in production cost that restricts large-scale commercialization. However, microbial pigments are progressively gaining popularity because of their health advantages. The development of metabolic engineering and cost reduction of the bioprocess using industry by-products opened possibilities for cost and quality improvements in all production phases. We are thus addressing several points related to microbial pigments, including the major classes and structures found, the advantages of use, the biotechnological applications in different industrial sectors, their characteristics, and their impacts on the environment and society.

Identification and biotechnological characterisation of yeast microbiota involved in spontaneous fermented wholegrain sourdoughs

BACKGROUND

New strategies in the cereal-based industry has brought about the elaboration of new sourdoughs with better microbial stability and safety as well as nutritional value such as those based on wholegrain flours. This has led to an increasing interest in the selection of adapted yeasts for using them as new starters. Therefore, this study aimed to isolate, identify, and characterise diverse yeast strains from wholegrain spontaneous sourdoughs.

RESULTS

Three wholegrain sourdoughs (wheat, rye, and oat) were fermented and monitored for 96 h. Minimum pH values ranged from 3.1 to 3.5 while maximum yeast counts were reached at 72 h. A total of 76 yeast isolates were identified by polymerase chain reaction random amplification of polymorphic DNA (PCR-RAPD) and catalogued in six different species by sequencing the internal transcribed spacer (ITS) region. The major species were Candida glabrata, Saccharomyces cerevisiae, Kazachstania unispora, and Wickerhamomyces anomalus. The studied kinetic parameters of the growth curves (λ, G, ODmax , and μmax ) and the fermentation capacity allowed to ascertain that 12 and 5 strains, respectively, were better than baker's yeast control. The fibre assimilation ability (cellulose, xylose, and β-glucan) was observed in the 27% of the strains and only four strains showed phytase activity.

CONCLUSIONS

The yeast population in the three wholegrain sourdoughs were variable along the fermentation time. Genetic identification showed that strains and species presented a different trend for each sourdough although common species were determined (e.g., W. anomalus). Candida glabrata (4T1) and Saccharomyces cerevisiae (3A6) showed, respectively, better kinetics and impedance results than the positive control, while W. anomalus (C4) was notorious in fibre assimilation and phytase degradation. © 2023 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

The regulation of key flavor of traditional fermented food by microbial metabolism: A review

The beneficial microorganisms in food are diverse and complex in structure. These beneficial microorganisms can produce different and unique flavors in the process of food fermentation. The unique flavor of these fermented foods is mainly produced by different raw and auxiliary materials, fermentation technology, and the accumulation of flavor substances by dominant microorganisms during fermentation. The succession and metabolic accumulation of microbial flora significantly impacts the distinctive flavor of fermented foods. The investigation of the role of microbial flora changes in the production of flavor substances during fermentation can reveal the potential connection between microbial flora succession and the formation of key flavor compounds. This paper reviewed the evolution of microbial flora structure as food fermented and the key volatile compounds that contribute to flavor in the food system and their potential relationship. Further, it was a certain guiding significance for food industrial production.

Microbiome Assembly in Fermented Foods

For thousands of years, humans have enjoyed the novel flavors, increased shelf-life, and nutritional benefits that microbes provide in fermented foods and beverages. Recent sequencing surveys of ferments have mapped patterns of microbial diversity across space, time, and production practices. But a mechanistic understanding of how fermented food microbiomes assemble has only recently begun to emerge. Using three foods as case studies (surface-ripened cheese, sourdough starters, and fermented vegetables), we use an ecological and evolutionary framework to identify how microbial communities assemble in ferments. By combining in situ sequencing surveys with in vitro models, we are beginning to understand how dispersal, selection, diversification, and drift generate the diversity of fermented food communities. Most food producers are unaware of the ecological processes occurring in their production environments, but the theory and models of ecology and evolution can provide new approaches for managing fermented food microbiomes, from farm to ferment.

Online Monitoring of Sourdough Fermentation Using a Gas Sensor Array with Multivariate Data Analysis

Sourdough can improve bakery products' shelf life, sensory properties, and nutrient composition. To ensure high-quality sourdough, the fermentation has to be monitored. The characteristic process variables for sourdough fermentation are pH and the degree of acidity measured as total titratable acidity (TTA). The time- and cost-intensive offline measurement of process variables can be improved by utilizing online gas measurements in prediction models. Therefore, a gas sensor array (GSA) system was used to monitor the fermentation process of sourdough online by correlation of exhaust gas data with offline measurement values of the process variables. Three methods were tested to utilize the extracted features from GSA to create the models. The most robust prediction models were achieved using a PCA (Principal Component Analysis) on all features and combined two fermentations. The calibrations with the extracted features had a percentage root mean square error (RMSE) from 1.4% to 12% for the pH and from 2.7% to 9.3% for the TTA. The coefficient of determination (R2) for these calibrations was 0.94 to 0.998 for the pH and 0.947 to 0.994 for the TTA. The obtained results indicate that the online measurement of exhaust gas from sourdough fermentations with gas sensor arrays can be a cheap and efficient application to predict pH and TTA.

Effects of Co-Fermentation of Lactiplantibacillus plantarum and Saccharomyces cerevisiae on Digestive and Quality Properties of Steamed Bread

The leavening of wheat-based steamed bread is carried out either with a pure yeast culture or with traditional starter cultures containing both lactic acid bacteria and yeast/mold. The use of variable starter cultures significantly affects steamed bread's quality attributes, including nutritional profile. In this paper, differences in physicochemical properties, the type of digested starch, the production of free amino acids, and the specific volume of steamed bread under three fermentation methods (blank, yeast, and LP-GM4-yeast) were compared. The digestion characteristics (protein and starch hydrolysis) of steamed bread produced by using either yeast alone or a combination of Lactiplantibacillus plantrum and yeast (LP-GM4-yeast) were analyzed by an in vitro simulated digestion technique. It was found that the specific volume of steamed bread fermented by LP-GM4-yeast co-culture was increased by about 32%, the proportion of resistant starch was significantly increased (more than double), and soluble protein with molecular weight of 30-40 kDa was significantly increased. The results of this study showed that steamed bread produced by LP-GM4-yeast co-culture is more beneficial to human health than that by single culture.

Effect of the controlled fermented quinoa containing protective starter culture on technological characteristics of wheat bread supplemented with red lentil

Selected antifungal lactic acid bacteria (LAB) isolated from mature spontaneous quinoa sourdough was used as potential starter culture to produce loaf wheat bread containing controlled fermented quinoa (CFQ) supplemented with red lentil (RL) flour. Phylogenetic evolutionary tree led to the identification of Enterococcus hirae as the selected LAB isolate. Furthermore, there was no significant difference (P > 0.05) between bread containing CFQ and control in terms of hardness. The highest loaf specific volume and overall acceptability were also observed in control sample and wheat bread containing CFQ + RL, respectively. Meanwhile, the rate of surface fungal growth on wheat bread enriched with CFQ was significantly lower than the other samples. In accordance with a non-linear multivariable model, positive and negative correlations were observed between porosity and specific volume (+ 0.79), and also specific volume and crumb hardness (- 0.70), respectively. Accordingly, CFQ can be used as bio-preservative to produce clean-label supplemented wheat bread.

Up-Cycling Grape Pomace through Sourdough Fermentation: Characterization of Phenolic Compounds, Antioxidant Activity, and Anti-Inflammatory Potential

Despite its appealing composition, because it is rich in fibers and polyphenols, grape pomace, the major by-product of the wine industry, is still discarded or used for feed. This study aimed at exploiting grape pomace functional potential through fermentation with lactic acid bacteria (LAB). A systematic approach, including the progressively optimization of the grape pomace substrate, was used, evaluating pomace percentage, pH, and supplementation of nitrogen and carbon sources. When grape pomace was used at 10%, especially without pH correction, LAB cell viability decreased up to 2 log cycles. Hence, the percentage was lowered to 5 or 2.5% and supplementations with carbon and nitrogen sources, which are crucial for LAB metabolism, were considered aiming at obtaining a proper fermentation of the substrate. The optimization of the substrate enabled the comparison of strains performances and allowed the selection of the best performing strain (Lactiplantibacillus plantarum T0A10). A sourdough, containing 5% of grape pomace and fermented with the selected strain, showed high antioxidant activity on DPPH and ABTS radicals and anti-inflammatory potential on Caco2 cells. The anthocyanins profile of the grape pomace sourdough was also characterized, showing qualitative and quantitative differences before and after fermentation. Overall, the grape pomace sourdough showed promising applications as a functional ingredient in bread making.

Does sourdough bread provide clinically relevant health benefits?

During the last decade, scientific interest in and consumer attention to sourdough fermentation in bread making has increased. On the one hand, this technology may favorably impact product quality, including flavor and shelf-life of bakery products; on the other hand, some cereal components, especially in wheat and rye, which are known to cause adverse reactions in a small subset of the population, can be partially modified or degraded. The latter potentially reduces their harmful effects, but depends strongly on the composition of sourdough microbiota, processing conditions and the resulting acidification. Tolerability, nutritional composition, potential health effects and consumer acceptance of sourdough bread are often suggested to be superior compared to yeast-leavened bread. However, the advantages of sourdough fermentation claimed in many publications rely mostly on data from chemical and in vitro analyzes, which raises questions about the actual impact on human nutrition. This review focuses on grain components, which may cause adverse effects in humans and the effect of sourdough microbiota on their structure, quantity and biological properties. Furthermore, presumed benefits of secondary metabolites and reduction of contaminants are discussed. The benefits claimed deriving from in vitro and in vivo experiments will be evaluated across a broader spectrum in terms of clinically relevant effects on human health. Accordingly, this critical review aims to contribute to a better understanding of the extent to which sourdough bread may result in measurable health benefits in humans.

Sourdough "Biga" Fermentation Improves the Digestibility of Pizza Pinsa Romana: An Investigation through a Simulated Static In Vitro Model

Baked goods manufacturing parameters and fermentation conditions interfere with the nutrients content and affect their gastrointestinal fate. Pinsa Romana is a type of pizza that, recently, has been commercially rediscovered and that needed elucidation from a nutritional and digestibility perspective. In this study, six types of Pinsa Romana (five made with indirect method and one produced with straight dough technology) were characterized for their biochemical and nutritional features. Several variables like indirect (biga) Pinsa Romana production process, fermentation time and use of sourdough were investigated. The Pinsa Romana made with biga including sourdough and fermented for 48 h at 16 °C ((PR_48(SD)) resulted in the lowest predicted glycemic index, in the highest content of total peptides, total and individual free amino acids and gamma-amino butyric acid (GABA), and in the best protein quality indexes (protein efficiency ratio and nutritional index). The static in vitro digestion showed that the digesta from PR_48(SD) confirmed a reduced in vitro glycemic response after intake, and it showed a lower bioavailability of hydrophilic peptides. Furthermore, the inclusion of sourdough in biga enhanced the bioavailability of protein-related end-products including human health promoting compounds such as essential amino acids.

Use of Selected Lactic Acid Bacteria and Carob Flour for the Production of a High-Fibre and "Clean Label" Plant-Based Yogurt-like Product

Carob, an underutilized crop with several ecological and economic advantages, was traditionally used as animal feed and excluded from the human diet. Yet, nowadays, its beneficial effects on health are making it an interesting candidate as a food ingredient. In this study, a carob-based yogurt-like product was designed and fermented with six lactic acid bacteria strains, whose performances after fermentation and during shelf life were assessed through microbial and biochemical characterization. The strains showed different aptitudes to ferment the rice-carob matrix. Particularly, Lactiplantibacillus plantarum T6B10 was among the strains with the lowest latency phase and highest acidification at the end of fermentation. T6B10 also showed discrete proteolysis during storage, so free amino acids were up to 3-fold higher compared to the beverages fermented with the other strains. Overall, fermentation resulted in the inhibition of spoilage microorganisms, while an increase in yeasts was found in the chemically acidified control. The yogurt-like product was characterized by high-fiber and low-fat content; moreover, compared to the control, fermentation decreased the predicted glycemic index (-9%) and improved the sensory acceptability. Thus, this work demonstrated that the combination of carob flour and fermentation with selected lactic acid bacteria strains represents a sustainable and effective option to obtain safe and nutritious yogurt-like products.

Metataxonomic insights in the distribution of Lactobacillaceae in foods and food environments

Members of the family Lactobacillaceae, which now includes species formerly belonging to the genera Lactobacillus and Pediococcus, but also Leuconostocaceae, are of foremost importance in food fermentations and spoilage, but also as components of animal and human microbiota and as potentially pathogenic microorganisms. Knowledge of the ecological distribution of a given species and genus is important, among other things, for the inclusion in lists of microorganisms with a Qualified Presumption of Safety or with beneficial use. The objective of this work is to use the data in FoodMicrobionet database to obtain quantitative insights (in terms of both abundance and prevalence) on the distribution of these bacteria in foods and food environments. We first explored the reliability of taxonomic assignments using the SILVA v138.1 reference database with full length and partial sequences of the 16S rRNA gene for type strain sequences. Full length 16S rRNA gene sequences allow a reasonably good classification at the genus and species level in phylogenetic trees but shorter sequences (V1-V3, V3-V4, V4) perform much worse, with type strains of many species sharing identical V4 and V3-V4 sequences. Taxonomic assignment at the genus level of 16S rRNA genes sequences and the SILVA v138.1 reference database can be done for almost all genera of the family Lactobacillaceae with a high degree of confidence for full length sequences, and with a satisfactory level of accuracy for the V1-V3 regions. Results for the V3-V4 and V4 region are still acceptable but significantly worse. Taxonomic assignment at the species level for sequences for the V1-V3, V3-V4, V4 regions of the 16S rRNA gene of members of the family Lactobacillaceae is hardly possible and, even for full length sequences, and only 49.9 % of the type strain sequences can be unambiguously assigned to species. We then used the FoodMicrobionet database to evaluate the prevalence and abundance of Lactobacillaceae in food samples and in food related environments. Generalist and specialist genera were clearly evident. The ecological distribution of several genera was confirmed and insights on the distribution and potential origin of rare genera (Dellaglioa, Holzapfelia, Schleiferilactobacillus) were obtained. We also found that combining Amplicon Sequence Variants from different studies is indeed possible, but provides little additional information, even when strict criteria are used for the filtering of sequences.

Molecular and Technological Characterization of Saccharomyces cerevisiae from Sourdough

DNA markers help detect the intraspecific genetic diversity of yeast strains. Eight ISSR (Inter Simple Sequence Repeats) primers were used to assess the intraspecific diversity of Saccharomyces cerevisiae (n = 96) from different populations (n = 3), evaluate the technological characteristics, and investigate trait-loci associations. The primers amplified 154 reproducible and scorable bands, of which 79.87% were polymorphic. The UPGMA (unweighted pair group method with arithmetic mean) dendrogram clustered 96 isolates into two main clusters, supported by STRUCTURE HARVESTER results (ΔK = 2). Analysis of molecular variance (AMOVA) indicated significant genetic differences between (15%) and within the populations (85%) (p < 0.001). Twenty-nine genetically distinct strains were selected for the technological characterization. Principal component analysis (PCA) revealed that five strains with high fermentation capacity, leavening activity, high growth index at 37 °C, and harsh growth conditions were technologically relevant. Trait-loci association analyses indicated that the highest correlation (r = 0.60) was recorded for the fermentation capacity on the 8th and 113th loci, amplified by ISSR-1 and ISSR-6 primers, respectively (p < 0.05). The strains yielding high performances and the associated loci amplified by ISSR markers possess a high potential to generate locus-specific primers to target the strains with high fermentation capacity.

Metabolic Profile of Einkorn, Spelt, Emmer Ancient Wheat Species Sourdough Fermented with Strain of Lactiplantibacillus plantarum ATCC 8014

The continuous development of bakery products as well as the increased demands from consumers transform ancient grains into alternatives with high nutritional potential for modern wheat species. The present study, therefore, follows the changes that occur in the sourdough obtained from these vegetable matrices fermented by Lactiplantibacillus plantarum ATCC 8014 during a 24 h. period. The samples were analyzed in terms of cell growth dynamics, carbohydrate content, crude cellulose, minerals, organic acids, volatile compounds, and rheological properties. The results revealed significant microbial growth in all samples, with an average value of 9 log cfu/g but also a high accumulation of organic acids with the increase in the fermentation period. Lactic acid content ranged from 2.89 to 6.65 mg/g, while acetic acid recorded values between 0.51 and 1.1 mg/g. Regarding the content of simple sugars, maltose was converted into glucose, and fructose was used as an electron acceptor or carbon source. Cellulose content decreased as a result of the solubilization of soluble fibers into insoluble fibers under enzymatic action, with percentages of 3.8 to 9.5%. All sourdough samples had a high content of minerals; the highest of which-Ca (246 mg/kg), Zn (36 mg/kg), Mn (46 mg/kg), and Fe (19 mg/kg)-were recorded in the einkorn sourdough.

Rheo-Fermentation Dough Properties, Bread-Making Quality and Aroma Characteristics of Red Bean (Vigna angularis) Sourdough Induced by LAB Weissella confusa QS813 Strain Fermentation

This study investigated the impact of in situ-formed exopolysaccharides (EPS) in red bean (Vigna angularis) sourdough fermented by Weissella confusa QS813 on dough rheo-fermentation properties, bread-making quality and aroma characteristics of red bean sourdough bread. The EPS formed in red bean sourdough and sourdough-induced acidification improved the maximum dough fermentation height, gas retention coefficient and viscoelastic properties of dough. Doughs had a lower increase rate of total SDS-soluble gluten proteins, a low decline in GMP content and similar free sulfhydryl content to wheat dough. Resultantly, breads showed declines in baking loss and hardness, increase in specific volume and lower moisture loss and staling rate after 7 days of storage. Finally, despite a reduction in the total content of aroma compounds, new aroma compounds such as acetic acid and higher contents of 3-methyl-1-butanol and 2,3-butanediol were enriched in red bean sourdough bread. Sourdough acidification probably promoted interaction of EPS with gluten or red bean proteins through bond interactions to form structures which stabilized gluten in dough and increased water-binding ability in red bean sourdough bread. This study provided a better understanding of the role of EPS in sourdough in improving bread quality and of promising strategies to address consumer demand for nutritious and clean-label products.

The Effect of Hydrolyzed and Fermented Arabinoxylan-Oligo Saccharides (AXOS) Intake on the Middle-Term Gut Microbiome Modulation and Its Metabolic Answer

Although fermentation and hydrolyzation are well-known processes to improve the bioavailability of nutrients and enable the fortification with dietary fibers, the effect of such pre-treatments on the prebiotic features of arabinoxylan-oligosaccharides (AXOS) had not been explored. The middle-term in vitro simulation through the Simulator of the Human Intestinal Microbial Ecosystem (SHIME) demonstrated that the feeding with different formulations (namely oat bran, rye bran and wheat bran) containing hydrolyzed AXOS fermented by lactic acid bacteria significantly increased the synthesis of short-chain fatty acids (SCFA) by colon microbiota, with hydrolyzed and fermented rye bran displaying the highest effect. After two weeks from the interruption of intake, SCFA concentrations significantly decreased but remained still significantly higher compared to the original condition. The microbiome was also affected, with a significant abundance increase in Lactobacillaceae taxon after feeding with all fermented and hydrolyzed formulates. Hydrolyzed and fermented rye bran showed the highest changes. The fungal community, even if it had a lower variety compared to bacteria, was also modulated after feeding with AXOS formulations, with an increase in Candida relative abundance and a decrease in Issatchenkia. On the contrary, the intake of non-hydrolyzed and non-fermented wheat bran did not produce relevant changes of relative abundances. After two weeks from intake interruption (wash out period) such changes were mitigated, and the gut microbiome modulated again to a final structure that was more like the original condition. This finding suggests that hydrolyzed AXOS fermented by lactic acid bacteria could have a more powerful prebiotic effect compared to non-hydrolyzed and non-fermented wheat bran, shaping the colon microbiome and its metabolic answer. However, the intake should be continuous to assure persistent effects. Opening a window into the ecological evolutions and plausible underlying mechanisms, the findings reinforce the perspective to explore more in depth the use of hydrolyzed and fermented AXOS as additional ingredient for bread fortification.