Effect of selected strains on physical and organoleptic properties of breads

The production of esters by specific sourdough lactic acid bacteria species is limited by the precursor concentrations

The production of fruity esters by sourdough lactic acid bacteria (LAB) and yeasts has not been explored in detail. Moreover, the biosynthesis of esters by LAB species under conditions similar to those occurring during sourdough production is still questionable. Concerning yeasts, a genome mining of 75 genomes revealed a strain dependency of the presence of seven specific ester biosynthesis genes. Accordingly, PCR assays to detect these acetate (ATF1 and ATF2) and ethyl ester (EHT1 and EEB1) biosynthesis genes were developed and used to screen 91 strains of yeast species. Concerning LAB, a genome mining of 401 genomes revealed a species dependency of the presence of three esterase-encoding genes (estA, estB, and estC). A phenotypic analysis carried out with a selection of 10 strains of the LAB species Companilactobacillus crustorum, Companilactobacillus nantensis, Companilactobacillus paralimentarius, Fructilactobacillus sanfranciscensis, Lactiplantibacillus xiangfangensis, Levilactobacillus zymae, and Limosilactobacillus fermentum in a wheat sourdough simulation medium (WSSM) supplemented with ester precursor molecules ([higher] alcohols and fatty acids) revealed that their ester biosynthesis capacity was limited by the precursor concentrations. Ethyl acetate and ethyl lactate were produced by all strains, except for those of Frul. sanfranciscensis. These results suggested that one of the esterase-encoding genes considered could be implicated in the ethyl acetate and/or ethyl lactate biosynthesis. Overall, the ester biosynthesis capacity by LAB is of great interest in view of fruity flavor formation during sourdough and sourdough bread productions.

IMPORTANCE

The present study gave insights into the production of esters, which impart fruity flavors to fermented foods, by not only sourdough yeasts but also lactic acid bacteria. It showed that some lactic acid bacteria species can synthesize the esters ethyl acetate (sweet notes) and ethyl lactate (creamy notes) under specific conditions. The information gathered during the present study will enable sourdough bakers and companies from the bakery sector to get more information on how to produce sourdoughs that can add fruity notes to the final products after a rational screening and selection of potential starter culture strains.

Cloning, characterization of β-glucosidase from Furfurilactobacillus rossiae in bioconversion and its efficacy

Minor ginsenosides produced by β-glucosidase are interesting biologically and pharmacologically. In this study, new ginsenoside-hydrolyzing glycosidase from Furfurilactobacillus rossiae DCYL3 was cloned and expressed in Escherichia coli strain BL21. The enzyme converted Rb1 and Gyp XVII into Rd and compound K following the pathways: Rb1→Rd and Gyp XVII→F2→CK, respectively at optimal condition: 40 °C, 15 min, and pH 6.0. Furthermore, we examined the cytotoxicity, NO production, ROS generation, and gene expression of Gynostemma extract (GE) and bioconverted Gynostemma extract (BGE) in vitro against A549 cell lines for human lung cancer and macrophage RAW 264.7 cells for antiinflammation, respectively. As a result, BGE demonstrated significantly greater toxicity than GE against lung cancer at a dose of 500 µg/mL but in normal cells showed lower toxicity. Then, we indicated an enhanced generation of ROS, which may be boosting cancer cell toxicity. By blocking the intrinsic way, BGE increased p53, Bax, Caspase 3, 9, and while Bcl2 is decreased. At 500 µg/mL, the BGE sample was less toxic in normal cells and decreased the LPS-treated NO and ROS level to reduce inflammation. In addition, BGE inhibited the expression of pro-inflammatory genes COX-2, iNOS, IL-6, and IL-8 in RAW 264.7 cells than the sample of GE. In conclusion, FrBGL3 has considerable downstream applications for high-yield, low-cost, effective manufacture of minor ginsenosides. Moreover, the study's findings imply that BGE would be potential materials for anti-cancer and anti-inflammatory agent after consideration of future studies.

Casein hydrolysate in naturally-fermented buckwheat sourdough: Effects on fermented and physicochemical characteristics, texture, and bacterial microbial composition

The effect of a casein hydrolysate (CH) on the fermentation and quality of a naturally-fermented buckwheat sourdough (NFBS) were investigated, through assessing the fermentation characteristics, carbohydrate and protein degradation, texture, and bacterial composition of NFBS. According to the assaying data, CH might both increase the amount of lactic acid bacteria by 2.62 % and shorten the fermentation period by at least 3 h, subsequently leading to enhanced degradation of carbohydrate and protein, accompanied by a softer texture. More importantly, CH increased the relative abundance of lactobacillus in NFBS, making it the dominant bacterial genus and inhibited the growth of spoilage bacteria. In addition, Spearman correlation analysis indicated that the pH value, lactic and acetic acid contents, carbohydrates, protease activity, and these textural indices like hardness, elasticity, and adhesion had a positive/negative correlation with the bacterial composition of NFBS (Spearman correlation coefficient: -0.93-0.95). CH was thus regarded to be helpful to NFBS processing and production mainly by shortening its fermentation time, improving its fermentation performance, causing a finer texture and microstructure, and changing bacterial composition.

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.

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.

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.

Influence of sprouted oat flour substitution on the texture and in vitro starch digestibility of wheat bread

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β-glucan reduced 45 % and polyphenols increased 79 % after sprouting for 120 h.

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Bread’s cell density and specific volume were the highest after sprouting for 72 h.

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The starch digestibility was the lowest with oat flour sprouting for 72 h.

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Two digestible fractions with different digestion rates was presented in the bread.

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Sprouting for 72 h postponed t_2start and reduced digestion rate by 7 % in the bread.

The aim of this study was to investigate the effect of sprouted oats substitutions on the in vitro digestibility of starch in the wheat bread. The physical and nutritional quality of wheat bread enriched with 20 % sprouted oat flour was compared. The polyphenols and γ-aminobutyric acid increased, while the content of starch and β-glucan in the mixed bread was gradually decreased. The specific volume of mixed bread reached the maximum with a 19.79 % reduction of area fraction and a 31.36 % increase cell density when sprouting for 72 h. Two digestible starch fractions with different digestion rates were observed from the LOS-CPS fitted starch digestograms. The microstructure revealed that large type A wheat starch was gelatinized after baking, whereas small type B wheat starch and oat starch were wrapped in protein-β-glucan complexes. This study suggests that properly sprouting has the potential to obtain nutritional bread with low starch digestibility.

Improvement of Sourdough and Bread Qualities by Fermented Water of Asian Pears and Assam Tea Leaves with Co-Cultures of Lactiplantibacillus plantarum and Saccharomyces cerevisiae

Qualities of sourdough and sourdough bread using fermented water from Asian pears and Assam tea leaves with Lactiplantibacillus plantarum 299v and Saccharomyces cerevisiae TISTR 5059 as starter cultures were evaluated. Changes in the growth of lactic acid bacteria and yeast, pH, sourdough height, total phenolic contents (TPCs) and antioxidant activities detected by ORAC, FRAP and DPPH radical scavenging assays were monitored during sourdough production. Mature sourdough was achieved within 4 h after 18 h retard fermentation and used for bread production. The bread was then analyzed to determine chemical and physical properties, nutritional compositions, TPCs, antioxidant activities and sensory properties as well as shelf-life stability. Results showed that fermented water significantly promoted the growth of yeast and increased TPCs and antioxidant activities of sourdough. Compared to common sourdough bread, fermented water sourdough bread resulted in 10% lower sugar and 12% higher dietary fiber with improved consumer acceptability; TPCs and antioxidant activities also increased by 2–3 times. The fermented water sourdough bread maintained microbial quality within the standard range, with adequate TPCs after storage at room temperature for 7 days. Fermented water from Asian pears and Assam tea leaves with L. plantarum 299v and S. cerevisiae TISTR 5059 as starter cultures improved dough fermentation and bread quality.

Lactic acid bacteria synergistic fermentation affects the flavor and texture of bread

Fermentation strains play a key role in the quality of bread. The combination of yeast and lactic acid bacteria (LAB) may effectively improve the function and nutritional properties of bread. In this study, the dough was fermented to make bread by using single strain (Saccharomyces cerevisiae, mode A), the combination of two strains (S. cerevisiae and Lactiplantibacillus plantarum, mode B; S. cerevisiae and Lactobacillus delbrueckii, mode C), or three strains (S. cerevisiae, L. plantarum, and L. delbrueckii, mode D). The specific volume, texture, and aroma substances of bread were evaluated. The possibility of mixed fermentation of selected yeast and LAB to replace natural fermentation dough was evaluated. The results showed that the specific volume of bread in mode B was 15.2% higher than that of mode A. The structure was softer and the taste was more vigorous in mode B bread. The content of volatile compounds was highest in mode B bread among the four mode bread. The characteristic flavors were ethyl 2-hydroxypropionate and z-3-hexenol. The cofermentation in mode B made the bread aroma richer and gave better aroma characteristics to bread. Therefore, the fermentation of S. cerevisiae and L. plantarum can be recommended to replace naturally fermented dough to improve the quality of bread. PRACTICAL APPLICATION: L. plantarum and L. delbrueckii, separately or together, assisted in yeast fermentation to make bread. The specific volume, texture, and aroma substances of bread were evaluated to replace natural fermented dough with mixed fermentation. L. plantarum-assisted yeast fermentation improved the specific volume, texture, and aroma of bread. The characteristic flavors were ethyl 2-hydroxypropionate and z-3-hexenol in bread. Therefore, the fermentation of S. cerevisiae and L. plantarum could replace naturally fermented dough to improve the quality of bread.

Amaranth selective hydrolyzed protein influence on sourdough fermentation and wheat bread quality

Amaranth selective hydrolyzed protein (ASPH) may improve sourdough properties and bread quality. In this regard, this study focused on investigating the influence of protein hydrolysates on sourdough fermentation and bread properties. Based on the findings, ASPH further increased Lactobacillus plantarum and Saccharomyces cerevisiae growth in sourdough compared with amaranth protein isolates and amaranth flour. ASPH at 5 g/kg resulted in sourdough with higher pH and total titratable acidity (TTA) after 20 h of fermentation at 30°C. The prepared sourdough using APH (S-ASPH) at 3 g/kg increased the specific volume (4.57 ml/g) and TTA (4.76 ml) while decreasing water activity, hardness, cohesiveness, and chewiness of the bread (S-ASPH-B) compared with the control. Moreover, transition temperature and enthalpy reduced whereas sensory properties and shelf life represented an increase with S-ASPH addition. Overall, the obtained data indicated the improvement of bread quality by S-ASPH sourdough.