Influence of temperature and of starter culture on biochemical characteristics and the aromatic compounds evolution on type II sourdough and wheat bread

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.

The effects of fermentation time on sourdough bread: An analysis of texture profile, starch digestion rate, and protein hydrolysis rate

To ensure the best quality bread, it is important to consider the speed of digestion of starch and proteins, as well as how time fermentation and storage time influence the rate of starch digestion and the texture of the bread. This study compared the effect of fermentation time and days of storage on the texture, physicochemical, protein and starch digestibility of sourdough bread. Texture profile analysis showed that the fermentation time in recently baked sourdough bread affects hardness, chewiness, and springiness. The electrophoretic profile showed a decrease in band thickness with increase in fermentation time, consistent with a higher percentage of protein digestion. While fermentation time did not significantly affect rapidly digestible starch (RDS) and slowly digestible starch (SDS), storage time resulted in a decrease in RDS and an increase in SDS. Sourdough breads had higher levels of resistant starch (RS). The digestibility characteristics of protein and starch, as well as texture properties, are significantly influenced by fermentation and storage time. The evidence suggests that sourdough bread has the potential to improve the digestion of protein and to effectively regulate the glycemic response, which is due to its higher levels of SDS and RS.

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.

In situ produced exopolysaccharides by Bacillus coagulansIBRC-M 10807 and its effects on properties of whole wheat sourdough

This study aimed to investigate in situ exopolysaccharides (EPSs) production by Bacillus coagulans IBRC-M 10807 under different fermentation conditions to improve the technical-functional properties of whole wheat flour sourdough and obtain high-quality products. For this purpose, the effectiveness of four efficient factors including B. coagulans (8 Log CFU/g), FOS (0%, 2.5%, and 5% based on flour weight), fermentation temperature (30, 35, and 40°C), and fermentation time (12, 18, and 24 h) was investigated on the production of functional sourdough. Our work focused on optimizing probiotic sourdough by investigating probiotic viability, pH, total titratable acidity, antioxidant properties, and EPS measurement. The first optimal formulation for maximized production of the in situ EPSs by the numerical optimization included FOS 0%, B. coagulans IBRC-M 10807 8 Log CFU/g, fermentation temperature of 30°C, and fermentation time of 12 h. In this case, EPSs was 59.28 mg/g and probiotic was 10.99 Log CFU/g. The second optimal formula by considering the highest viability of probiotic together with EPS production was determined as FOS 4.71%, B. coagulans IBRC-M 10807, 8 Log CFU/g, fermentation temperature of 30°C, and fermentation time of 20 h. The predicted amount of the EPSs and probiotic viability via the second formulation were 54.4 mg/g and 11.18 Log CFU/g, respectively. Analyses of optimal sourdough using FTIR, SEM, and DSC revealed that FOS and probiotics significantly reduced the enthalpy of amylopectin retrogradation and delayed it compared to other samples. Therefore, improving the final product's technological capabilities and shelf life can be credited with potential benefits.

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

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

Exploration of microbial profile of traditional starters and its influence on aroma profile and quality of Chinese steamed bread

BACKGROUND

Chinese steamed bread (CSB) is a popular staple food in China with traditional ethnic characteristics. CSB with traditional starters has good flavor and texture but is unstable and requires a long preparation time. Therefore, it is necessary to analyze the traditional starters (ST) and their influence on the flavor and quality of steamed bread to meet people's requirements as a staple food.

RESULTS

The count of yeast, lactic acid bacteria and total microbial population significantly varied in different traditional starters; Saccharomyces and Lactobacillus were the predominant genera. Among the tested samples, fungi were found in ST from Shijiazhuang (SJ), Handan (HD) and Langfang (LF), while bacteria were found in ST from Tangshan (TS) and SJ at sub-predominant levels. In terms of the bread quality, the highest specific volume and porosity were in XT-CSB (Xingtai); the highest height/diameter ratio was in SJ-CSB; and the highest sensory score was in TS-CSB. A total of 26 aroma compounds (VIP > 1; variable importance for predictive components) were identified to discriminate CSB fermented with different starters, which were separated by stepwise canonical discriminant analysis using two functions. The correlation analysis among microbiota, aroma compounds and bread quality showed a higher contribution of bacteria than of fungi.

CONCLUSION

Differences in microbial profiles caused different aroma profiles and quality of CSB; and the CSB fermented with traditional starters were sufficiently separated by stepwise canonical discriminant analysis based on aroma compounds. © 2023 Society of Chemical Industry.

Development and Optimization of Black Rice (Oryza sativa L.) Sourdough Fermented by Levilactobacillus brevis LUC 247 for Physicochemical Characteristics and Antioxidant Capacity

This study used Levilactobacillus brevis LUC 247 to ferment black rice sourdough, made into Type III black rice sourdough powder to produce black rice sourdough bread. The composition analysis, antioxidant capacity, and storage stability of the black rice sourdough bread with different proportions of black rice powder (0–60%) and fermented for different lengths of time (0–48 h) were discussed. The results showed that the black rice sourdough had the maximum lactic acid bacteria count (9 Log CFU/g) during 12 to 36 h of fermentation. The titratable acid, lactic acid, and acetic acid yields increased with the fermentation time and the proportion of black rice powder. The total anthocyanin content and antioxidant capacity increased with the fermentation time. The hardness and chewiness of the black rice sourdough bread were positively correlated with the black rice sourdough powder content and increased with storage time. In addition, the growth of fungi was significantly slowed as the additional level of black rice sourdough powder increased.

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.

Probiotics in the Sourdough Bread Fermentation: Current Status

Sourdough fermentation is an ancient technique to ferment cereal flour that improves bread quality, bringing nutritional and health benefits. The fermented dough has a complex microbiome composed mainly of lactic acid bacteria and yeasts. During fermentation, the production of metabolites and chemical reactions occur, giving the product unique characteristics and a high sensory quality. Mastery of fermentation allows adjustment of gluten levels, delaying starch digestibility, and increasing the bio-accessibility of vitamins and minerals. This review focuses on the main steps of sourdough fermentation, the microorganisms involved, and advances in bread production with functional properties. The impact of probiotics on human health, the metabolites produced, and the main microbial enzymes used in the bakery industry are also discussed.

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

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

Antifungal Capacity of Poolish-Type Sourdough Supplemented with Lactiplantibacillus plantarum and Its Aqueous Extracts In Vitro and Bread

This study aimed to evaluate the antifungal capacity of the aqueous extracts (AE) of poolish-type sourdoughs fermented with Lactiplantibacillus plantarum NRRL B-4496 on broth, agar, and bread. The aqueous extracts were obtained by centrifugation and separating the supernatant from the poolish sourdoughs once the fermentation time had ended. The aqueous extracts inhibited 80% of the growth of Penicillium chrysogenum and Penicillium corylophilum and <20% of Aspergillus niger in broth. The AEs delayed the radial growth rate and increased the lag time for the three molds tested. The addition of poolish-type sourdoughs inhibited fungal growth in bread for ten days. The extracts’ fungistatic capacity was primarily attributed to lactic and acetic acids and probably the antifungal peptides occurring in the AE. The L. plantarum sourdough is an alternative to calcium propionate as an organic antifungal agent.

Changes in the physicochemical parameters and microbial community of a new cultivar blue wheat cereal wholemeal during sourdough production

Changes in the characteristics of a new cultivar (DS8472-5) of blue wheat during wholemeal fermentation with Pediococcus acidilactici (LUHS29), Liquorilactobacillus uvarum (LUHS245), and Lactiplantibacillus plantarum (LUHS122), including acidity, microbiological and chromaticity parameters, free amino acid (FAA), gamma-aminobutyric acid (GABA), and biogenic amine (BA) contents, macro- and micro-element concentrations and fatty acid (FA) and volatile compounds (VC), were evaluated. In addition, a metagenomic analysis was performed. The lactic acid bacteria (LAB) strains used for fermentation was a significant factor in wholemeal fermentation sample pH, redness (a*) and LAB counts (p ≤ 0.05). In most of the samples, fermentation increased the FAA content in wheat wholemeal, and the highest concentration of GABA was found in DS8472-5 LUHS122 samples. Phenylethylamine (PHE) was found in all wheat wholemeal samples; however, spermidine was only detected in fermented samples and cadaverine only in DS8472-5 LUHS122. Fermented samples showed higher omega-3 and omega-6 contents and a higher number and variety of VC. Analysis of the microbial profile showed that LAB as part of the natural microbiota present in cereal grains also actively participates in fermentation processes induced by industrial bacterial cultures. Finally, all the tested LAB were suitable for DS8472-5 wheat wholemeal fermentation, and the DS8472-5 LUHS122 samples showed the lowest pH and the highest LAB viable counts (3.94, 5.80°N, and 8.92 log10 CFU/g, respectively).

Changes in the Volatile Profile of Wheat Sourdough Produced with the Addition of Cava Lees

The volatile fraction is of great importance for the organoleptic quality and consumer acceptance of bread. The use of sourdough improves the sensory profile of bread, as well as the addition of new ingredients to the fermentation. Cava lees are a sparkling wine by-product formed of dead microorganisms, tartaric acid, and other inorganic compounds, rich in antioxidant compounds as well as β-glucans and mannoproteins. The aim of this study was to evaluate the effect of different concentrations of Cava lees (0–2% w/w) on sourdough volatile compounds to re-valorize this by-product of the wine industry. Headspace solid-phase microextraction (HS-SPME) was optimized to study the volatile fractions of sourdoughs. The parameters selected were 60 °C, 15 min of equilibrium, and 30 min of extraction. It was found that the addition of Cava lees resulted in higher concentrations of volatile compounds (alcohols, acids, aldehydes, ketones and esters), with the highest values being reached with the 2% Cava lees. Moreover, Cava lees contributed to aroma due to the compounds usually found in sparkling wine, such as 1-butanol, octanoic acid, benzaldehyde and ethyl hexanoate.

Evaluation of the variations in chemical and microbiological properties of the sourdoughs produced with selected lactic acid bacteria strains during fermentation

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Chemical, microbiological and VOCs profile showed the relevance of starter addition.

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MiSeq Illumina confirmed that Lactobacillus spp. constituted the major LAB group.

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Fructilactobacillus sanfranciscensis was the most isolated LAB species.

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Rapid acidifying LAB strains should be preferred for sourdough production.

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Number of VOCs increased in sourdoughs produced with starter culture.

This research aimed to analyze variations in chemical properties, microbiological characteristics and generated volatile organic compounds (VOCs) profile during sourdough fermentation. Sourdoughs were collected from different cities in Turkey at two different times and lactic acid bacteria (LAB) in the samples were identified with culture-independent and culture-dependent molecular methods. According to culture-dependent methodology, thirteen LAB species were identified. Lactobacillus spp. were identified as the major group according to MiSeq Illumina analysis. Technological potential of commonly isolated LAB species was evaluated. Due to high frequency of isolation, Fructilactobacillus sanfranciscensis and Lactiplantibacillus plantarum strains were better investigated for their technological traits useful in sourdough production. Experimental sourdoughs were produced with mono- and dual-culture of the selected strains and chemical properties and microbiological characteristics, as well as VOCs profile of the sourdoughs, were subjected to multivariate analysis which showed the relevance of added starter, in terms of acidification and VOCs profile.

By-Product Revalorization: Cava Lees Can Improve the Fermentation Process and Change the Volatile Profile of Bread

Wine lees are a by-product that represents a 25% of the total winery waste. Although lees are rich in antioxidant compounds and dietary fiber, they have no added value and are considered a residue. The aim of this study was to evaluate the effect of Cava lees (0 and 5% w/w) on microbial populations during sourdough and bread fermentation and the volatile fraction of the final bread. The results showed that 5% Cava lees promoted the growth of both lactic acid bacteria (LAB) and yeast in short fermentations (bread) but did not improve microbial growth in long fermentations (sourdough). Regarding volatile compounds, the addition of Cava lees increased the concentration of volatiles typically found in those products. Also, some compounds reported in sparkling wines were also identified in samples with Cava lees adsorbed on their surface. To sum up, the addition of Cava lees to sourdough and, especially, bread formulation may be a new strategy to revalorize such by-product.

Statistical Approach to Potentially Enhance the Postbiotication of Gluten-Free Sourdough

Fermented products are permanently under the attention of scientists and consumers, both due to nutritional importance and health promoting effects. The fermented functional foods contribute to a more balanced diet and increase the immune responses (among many other health effects) with positive implications for quality of life. In this sense, improving the sourdough’s fermentation to boost the biotic (postbiotic and paraprobiotic) properties of the sourdough-based products has positive impacts on the nutritional and functional properties of the final baked products. These enhanced sourdoughs can be obtained in controlled fermentation conditions and used as sourdough bread improvers or novel bioingredients. In this context, our work aimed to optimize, using statistical tools, a gluten-free sourdough based on chickpea, quinoa, and buckwheat fermentation with selected lactic acid bacteria (LAB) to enhance its postbiotic properties. The most important biotechnological parameters were selected by Plackett–Burman Design (PBD) and then Response Surface Methodology (RSM) was applied to evaluate the interactions between the selected factors to maximize the gluten-free sourdough’s properties. As a result, the optimized fermented sourdough had antimicrobial activity with inhibition ratios between 71 and 100% against the Aspergillus niger, Aspergillus flavus, Penicillium spp. molds and against the Bacillus spp endospore-forming Gram-positive rods. The optimized variant showed a total titratable acidity (TTA) of 40.2 mL NaOH 0.1N. Finally, the high-performance liquid chromatography (HPLC) analysis highlighted a heterofermentative profile for the organic acids from the optimized sourdough. Among flavonoids and polyphenols, the level of caffeic and vanillic acids increased after lactic acid fermentation. The comparison between the optimized sourdough and the control evidenced significant differences in the metabolite profiles, thus highlighting its potential postbiotication effect.

A review of sourdough starters: ecology, practices, and sensory quality with applications for baking and recommendations for future research

The practice of sourdough bread-making is an ancient science that involves the development, maintenance, and use of a diverse and complex starter culture. The sourdough starter culture comes in many different forms and is used in bread-making at both artisanal and commercial scales, in countries all over the world. While there is ample scientific research related to sourdough, there is no standardized approach to using sourdough starters in science or the bread industry; and there are few recommendations on future directions for sourdough research. Our review highlights what is currently known about the microbial ecosystem of sourdough (including microbial succession within the starter culture), methods of maintaining sourdough (analogous to land management) on the path to bread production, and factors that influence the sensory qualities of the final baked product. We present new hypotheses for the successful management of sourdough starters and propose future directions for sourdough research and application to better support and engage the sourdough baking community.

Functional and Healthy Features of Conventional and Non-Conventional Sourdoughs

Sourdough is a composite ecosystem largely characterized by yeasts and lactic acid bacteria which are the main players in the fermentation process. The specific strains involved are influenced by several factors including the chemical and enzyme composition of the flour and the sourdough production technology. For many decades the scientific community has explored the microbiological, biochemical, technological and nutritional potential of sourdoughs. Traditionally, sourdoughs have been used to improve the organoleptic properties, texture, digestibility, palatability, and safety of bread and other kinds of baked products. Recently, novel sourdough-based biotechnological applications have been proposed to meet the demand of consumers for healthier and more natural food and offer new inputs for the food industry. Many researchers have focused on the beneficial effects of specific enzymatic activities or compounds, such as exopolysaccharides, with both technological and functional roles. Additionally, many studies have explored the ability of sourdough lactic acid bacteria to produce antifungal compounds for use as bio-preservatives. This review provides an overview of the fundamental features of sourdoughs and their exploitation to develop high value-added products with beneficial microorganisms and/or their metabolites, which can positively impact human health.

Effect of Different Fermentation Condition on Estimated Glycemic Index, In Vitro Starch Digestibility, and Textural and Sensory Properties of Sourdough Bread

This study aimed to evaluate the influence of sourdough fermentation on the estimated glycemic index (eGI), in vitro starch digestibility, and textural and sensory properties of eight experimentally prepared sourdough breads. Wheat and whole wheat flour bread samples were produced under different fermentation conditions (25 °C and 30 °C) and fermentation methods (type-1 and type-2). In type-1 fermentation, sourdough was obtained via spontaneous fermentation. Indigenous strains (Lactobacillus brevis ELB99, Lactiplantibacillus plantarum ELB75, and Saccharomyces cerevisiae TGM55) were used for type-2 fermentation. Fermentation type and temperature significantly affected eGI, the hydrolysis index (HI), the starch fraction, and the textural properties of the samples (p < 0.05). The resistant starch (RS) content increased after fermentation, while rapidly digestible starch (RDS), HI, and eGI decreased. RS values were significantly higher in type-2 than in type-1 at the same temperature for both flour types (p < 0.05). At 25 °C, RS values were higher in both fermentation types. In the white flour samples, eGI values were in the range of 60.8–78.94 and 62.10–78.94 for type-1 and type-2, respectively. The effect of fermentation type on eGI was insignificant (p < 0.05). In the whole flour samples, fermentation type and temperature significantly affected eGI (p < 0.05). The greatest eGI decreases were in whole wheat sourdough bread at 30 °C using type-2 (29.74%). The 30 °C and type-2 samples showed lower hardness and higher specific volume. This study suggests that fermentation type and temperature could affect the eGI and the textural and sensory properties of sourdough bread, and these factors should be considered during bread production. The findings also support the consumption of wheat and whole wheat breads produced by type-2 fermentation due to higher RS and slowly digestible starch (SDS) and lower RDS and eGI values.