Evaluation of functionally important lactic acid bacteria and yeasts from Nigerian sorghum as starter cultures for gluten-free sourdough preparation

Sourdough fermentation for the valorization of sorghum flour: Microbiota characterization and metabolome profiling

Due to a large adaptability to different cultivation conditions and limited input compared to other cereals, sorghum is considered an emerging crop. Its antioxidant properties, high fiber content and low glycemic index also make it a valuable addition to a healthy diet, nevertheless, the presence of antinutritional factors and the lack of gluten, hamper its use as food ingredient. This study investigated the impact of sourdough fermentation on sorghum nutritional quality. Lactic acid bacteria dominating sorghum flour and sourdough were identified by culture-dependent analysis revealing Lactiplantibacillus plantarum as the dominant species found in the mature sourdough, whereas Weissella cibaria and Weissella paramesenteroides were the species isolated the most after the first refreshment. Among yeasts, Saccharomyces cerevisiae was the most prevalent. Lactic acid bacteria pro-technological and functional performances as starter were evaluated in sorghum type-II sourdoughs through an integrated characterization combining chromatographic and NMR spectroscopic techniques. The metabolic profile of the strains mainly grouped together W. cibaria strains and W. paramesenteroides AI7 which distinguished for the intense proteolysis but also for the presence of compounds particularly interesting from a physiological perspective (allantoin, glutathione, γ-aminobutyric acid and 2-hydroxy-3-methylbutyric acid), whose concentration increased during fermentation in a species or strain specific matter.

Characterization of Lactic Acid Bacteria and Yeast from Grains as Starter Cultures for Gluten-Free Sourdough

With the increasing number of people affected by gluten consumption-related diseases, adhering to a gluten-free (GF) diet is the most effective preventive measure. Herein, we aimed to isolate and characterize the functional properties of autochthonous lactic acid bacteria (LAB) and yeast from various GF sourdoughs to determine their suitability in starter cultures for sourdough preparation. Three LAB, Weissella confusa BAQ2, Lactobacillus brevis AQ2, Leuconostoc citreum YC2, and Saccharomyces cerevisiae BW1, were identified. The isolated LAB exhibited greater TTA, faster acidification rates, and higher acid tolerance than commercial LAB. W. confusa BAQ2 exhibited the highest EPS production, W. confusa BAQ2 and L. brevis AQ2 showed high maltose utilization, and S. cerevisiae BW1 exhibited the highest CO2 production rate. Accordingly, all four microbial strains were mixed for the starter culture. The sourdough prepared with starter cultures exhibited differences in gas production depending on fermentation time, which influenced the volume of GF bread dough. GF bread prepared with fermented sourdough exhibited a 16% higher specific volume and enhanced crumb firmness and elasticity than that prepared using non-fermented sourdough. Thus, autochthonous LAB strains isolated from various GF sourdoughs can be used together to improve the quality of sourdough bread, demonstrating their potential for use in starter cultures for GF sourdough production.

Nutritional and sensory quality of Ofada rice sourdough bread made with selected lactic acid bacteria strains

Celiac disease ranks highest among immunological disorders attributed to gluten consumption thus, posing great demands on gluten-free products. Rice is a gluten-free cereal with promising dietary applications. Ofada rice, a native southwestern Nigerian variety, can be improved with sourdough technology to develop functional aglutenic bread. Ofada rice sourdough bread (ORSB) was made with Fructilactobacillus fructivorans RY1, Weissella viridescens RY9 and Lactobacillus acidophilus RY10 as individual and combined starter cultures. Physical qualities, proximate contents, sensorial attributes and shelf-life of the ORSBs were evaluated. Sourdough bread with the highest (3.10 cm3/g) and lowest specific volumes (2.02 cm3/g) were the sample made single culture of W. viridescens and F. fructivorans, respectively. The highest crude protein (8.48 %) was found in ORSB with only F. fructivorans and ORSB with L. acidophilus singly had the highest content (0.44 %) of crude fibre. Nevertheless, the least crude protein (5.25 %) and crude fibre (0.28 %) were observed in samples containing F. fructivorans, W. viridescens, and L. acidophilus as combined starters. The sourdough bread with F. fructivorans as a starter scored best for texture and overall acceptability. The ORSBs had shelf-life ranging from three to four days. It was revealed in the study that using the specific LAB starters could improve the physicochemical attributes and acceptability of bread from Ofada rice flour.

Gluten-free grains: Importance, processing and its effect on quality of gluten-free products

Gluten-enteropathy affects a significant number of people, making gluten a major concern in the food industry. With medical advancements, the diagnosis of allergies is becoming easier, and people who are allergic to gluten are recommended a complete gluten-free diet. Since wheat provides a major part of the energy and nutrition in the diet, its elimination affects nutrition intake of allergic population. Food scientists are working to formulate products using protein-rich gluten-free grains with quality attributes at par with gluten-containing products. Focused research has been done to provide nutrition and a variety of food to people suffering from gluten-related disorders. Efforts are being made to remove the gluten from the wheat and other gluten-containing grains, while applying different processing/treatments to enhance the properties of gluten-free grains. Hence, the present review summarizes the importance, processing, and products of different gluten-free grains. It also highlights the digestibility of gluten-free grains with clinical trials and gluten elimination strategies for gluten-containing grains.

Screening of Sourdough Starter Strains and Improvements in the Quality of Whole Wheat Steamed Bread

In this study, yeast, lactic acid bacteria, and acetic acid bacteria were isolated from traditional Chinese sourdough to enhance the organoleptic quality of whole wheat steamed bread. The Saccharomyces cerevisiae, Lactobacillus johnsonii, and Acetobacter pasteurianum showed superior fermentability and acid production capacity when compared with other strains from sourdough, which were mixed to produce the compound starter. It was found that the volume of whole wheat steamed bread leavened with compound starter increased by 12.8% when compared with that of the whole wheat steamed bread made by commercial dry yeast (DY-WB). A total of 38 volatile flavors were detected in the whole wheat steamed bread fermented by the compound starter (CS-WB), and the type of volatile flavors increased by 14 species when compared to the bread fermented by the dry yeast. In addition, some unique volatile flavor substances were detected in CS-WB, such as acetoin, 3-hydroxy-butanal, butyraldehyde, cuparene, etc. Moreover, the hardness and the chewiness of CS-WB decreased by 31.1 and 33.7% when compared with DY-WB, respectively, while the springiness increased by 10.8%. Overall, the formulated compound starter showed a desirable improvement in the whole wheat steamed bread and could be exploited as a new ingredient for steamed bread.

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

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

Sourdough Microbiome Comparison and Benefits

Sourdough is the oldest form of leavened bread used as early as 2000 BC by the ancient Egyptians. It may have been discovered by accident when wild yeast drifted into dough that had been left out resulting in fermentation of good microorganisms, which made bread with better flavour and texture. The discovery was continued where sourdough was produced as a means of reducing wastage with little known (at that point of time) beneficial effects to health. With the progress and advent of science and technology in nutrition, sourdough fermentation is now known to possess many desirable attributes in terms of health benefits. It has become the focus of attention and practice in modern healthy eating lifestyles when linked to the secret of good health. The sourdough starter is an excellent habitat where natural and wild yeast plus beneficial bacteria grow by ingesting only water and flour. As each sourdough starter is unique, with different activities, populations and interactions of yeast and bacteria due to different ingredients, environment, fermentation time and its carbohydrate fermentation pattern, there is no exact elucidation on the complete make-up of the sourdough microbiome. Some lactic acid bacteria (LAB) strains that are part of the sourdough starter are considered as probiotics which have great potential for improving gastrointestinal health. Hence, from a wide literature surveyed, this paper gives an overview of microbial communities found in different sourdough starters. This review also provides a systematic analysis that identifies, categorises and compares these microbes in the effort of linking them to specific functions, particularly to unlock their health benefits.

Fermentation of Gluten by Lactococcus lactis LLGKC18 Reduces its Antigenicity and Allergenicity

Wheat is a worldwide staple food, yet some people suffer from strong immunological reactions after ingesting wheat-based products. Lactic acid bacteria (LAB) constitute a promising approach to reduce wheat allergenicity because of their proteolytic system. In this study, 172 LAB strains were screened for their proteolytic activity on gluten proteins and α-amylase inhibitors (ATIs) by SDS-PAGE and RP-HPLC. Gliadins, glutenins, and ATI antigenicity and allergenicity were assessed by Western blot/Dot blot and by degranulation assay using RBL-SX38 cells. The screening resulted in selecting 9 high gluten proteolytic strains belonging to two species: Enterococcus faecalis and Lactococcus lactis. Proteomic analysis showed that one of selected strains, Lc. lactis LLGKC18, caused degradation of the main gluten allergenic proteins. A significant decrease of the gliadins, glutenins, and ATI antigenicity was observed after fermentation of gluten by Lc. lactis LLGKC18, regardless the antibody used in the tests. Also, the allergenicity as measured by the RBL-SX38 cell degranulation test was significantly reduced. These results indicate that Lc. lactis LLGKC18 gluten fermentation can be deeply explored for its capability to hydrolyze the epitopes responsible for wheat allergy.

Sourdough Bread from the Blend of Cassava, Sweet Potato, and Soybean Flours Using Lactobacillus Plantarum and Pichia Kudriavzevii

Sourdough is specialty bread made from a combination of flour, lactic acid bacteria, and yeasts. Composite flour of cassava, sweet potato, and soybean was used for the production of sourdough bread employing autochthonous lactic acid bacteria and yeasts isolated from the composite dough. The flour samples were assessed for functional properties, while the sourdough breads were evaluated for nutritional composition and organoleptic properties. The flour samples possessed good proximate profiles and phenolic contents. The lactic acid bacterium and yeast with the most desirable properties were identified as Lactobacillus plantarum and Pichia kurdriazevii. Fermentation improved the nutritional indices of the composite sourdough bread samples. Lactobacillus plantarum SLC21 and P. kudriavzevii SYD17 bread had a shelf life of 7 days, while the control bread lasted for at least 4 days. Lactobacillus plantarum SLC21 and Pichia kudriavzevii SYD17 bread had the best overall acceptability. Utilisation of these local crops in a composite blend for sourdough will increase commercial profit for local farmers and developing economy. The composite blend will be of great importance in the preparation of pastries that do not require high gluten content. The strains exhibited great potentials for a better nutritional composition of the composite sourdough bread.

Technological Performance and Selection of Lactic Acid Bacteria Isolated from Argentinian Grains as Starters for Wheat Sourdough

The selection of lactic acid bacteria strains is interesting for the development of sourdough to obtain wheat bread with improved technological and nutritional properties. In this work, the performance of ten different LAB strains isolated from diverse cereals in wheat sourdough was evaluated. Five facultative heterofermentative (Lactobacillus pentosus ES124, Lactobacillus paralimentarius ES259, Lactobacillus plantarum ES137, Lactobacillus plantarum ATCC8014 and Lactobacillus plantarum ES147), three obligately heterofermentative (Lactobacillus brevis ES253, Lactobacillus fermentum ES142 and Lactobacillus fermentum ES148) and two homofermentative (Pediococcus acidilactici ES22 and Enterococcus faecium ES74) lactic acid bacteria strains were evaluated in ten single strain fermentations. Sugar profile, volatile compounds and proteolytic ability of sourdoughs were analyzed. The microbiological counts showed that facultative heterofermentative strains presented higher counts than homofermentative sourdoughs. Monosaccharides (glucose and fructose), maltose and sucrose, isomaltose and dextrin were detected in fermentations with homofermentative strains whilst in those with heterofermentative strains maltose/sucrose, isomaltose and dextrin were found. L. paralimentarius ES259 and L. pentosus ES124 showed the highest diversity of volatile compounds. L. plantarum ES137 and P. acidilactici ES22 were the strains with the highest proteolytic activity. The technological performance allowed us to select LAB as starters to develop breads with specific rheological properties and final quality.

Selection of Wild Lactic Acid Bacteria Strains as Promoters of Postbiotics in Gluten-Free Sourdoughs

The occurrence of inflammatory responses in humans is frequently associated with food intolerances and is likely to give rise to irritable bowel disease. The use of conventional or unconventional flours to produce gluten-free baking doughs brings important technological and nutritional challenges, and the use of the sourdough biotechnology has the potential to overcome such limitations. In addition, the typical metabolic transformations carried out by Lactic Acid Bacteria (LAB) can become an important biotechnological process for the nutritional fortification and functionalization of sourdoughs due to the resulting postbiotics. In such a context, this research work aimed at isolating and selecting new LAB strains that resort to a wide range of natural environments and food matrices to be ultimately employed as starter cultures in gluten-free sourdough fermentations. Nineteen LAB strains belonging to the genera of Lactobacillus, Leuconostoc, Pediococcus, and Streptococcus were isolated, and the selection criteria encompassed their acidification capacity in fermentations carried out on chickpea, quinoa, and buckwheat flour extracts; the capacity to produce exopolysaccharides (EPS); and the antimicrobial activity against food spoilage molds and bacteria. Moreover, the stability of the LAB metabolites after the fermentation of the gluten-free flour extracts submitted to thermal and acidic treatments was also assessed.

Lactobacillus-fermented sourdoughs improve the quality of gluten-free bread made from pearl millet flour

The study investigated the effect of sourdough made from combinations of four Lactobacillus spp. on the physicochemical properties, consumer acceptability, and shelf life of bread made from pearl millet flour. Fermentation based on both single and multiple species reduced the pH of the dough and increased its titratable acidity and H₂O₂ content. The addition of sourdough increased the elasticity and reduced the stiffness of the pearl millet dough. Sourdough fermented with L. brevis had the greatest effect on loaf height, specific volume, porosity, and moisture content. During storage, the moisture content of the bread crumb decreased, but that of their crust increased. Sourdough-based loaves retained their moisture better than conventional loaves and the sourdough suppressed the development of mold for a longer period. An organoleptic assessment showed that the sourdough-based bread was more palatable than either conventional or chemically acidified ones. The tissue softness, chewiness, and flavor of the pearl millet bread decreased during storage. The use of sourdough based on either L. brevis, L. paralimentarius, or L. brevis + L. paralimentarius is recommended to produce high-quality pearl millet-based bread.