102 research outputs found
Zymomonas mobilis: biomass production and use as a dough leavening agent
No full textZymomonas mobilis ferments only glucose, fructose and sucrose via the Entner-Doudoroff pathway, providing an equimolar mixture of ethanol and CO2 and theoretically, as for Saccharomyces cerevisiae, the gas evolved can be used to leaven a dough. However, the capability of Z. mobilis to produce CO2 has rarely been exploited. In the present study we first evaluated the growing performance of two Z. mobilis strains (DSMZ 424 and 3580) in a culture medium lacking yeast extract, with added glucose or fructose (20 and 50 g/L) comparatively; the results demonstrated that biomass yield is 50 % higher with glucose. The best conditions were up-scaled, obtaining a biomass yield of 1.3–1.4 g dcw/L in a 14-L fermenter. Leavening trials performed in a model system with the biomass collected from fermenters after 9 or 16 h incubation evidenced that Z. mobilis can leaven a model dough as S. cerevisiae does, and showing a CO2 production rate (9–11 mL g dcw−1 min−1) statistically higher than that of S. cerevisiae (6–7 mL g dcw−1 min−1), especially when using 9-h-grown biomass. Bakery products leavened with Z. mobilis could thus be available to people with adverse responses to the ingestion of bakery food, providing innovation in the area of yeast-free leavened baked goods
Yeast-Free Doughs by Zymomonas mobilis: Evaluation of Technological and Fermentation Performances by Using a Metabolomic Approach
No full textThis research focuses on the leavening performances and development of volatile compounds of three strains of Zymomonas mobilis in the production of yeast-free doughs. Z. mobilis DSM 3580, 424, and 473 were used in doughs supplemented with glucose and with or without NaCl. Z. mobilis produced about 10 mg ethanol/g dough, with maximum dough volumes (640–680 mL) being reached after 2 h leavening. NaCl addition postponed this parameter up to 6 h. Among organic acids, hexanoic acid resulted the highest produced compound; DSM 424 and 473 formed more propanoic, butanoic and pentanoic acid, being both negatively affected by NaCl. Esters were mainly discriminated on NaCl addition, with octanoic acid (DSM 3580), butanoic acid (DSM 424), and propanoic acid (DSM 473) ethyl esters as main components. DSM 3580 specifically produced 2-heptanal, DSM 424 2-hexadecenal, (E) and DSM 473 octanal, while DSM 424 and DSM 473 produced 2-butanone-4-hydroxy better than DSM 3580. Z. mobilis unique signatures were the production of nonanoic and undecanoic acids, 2-hexadecenal, (E), L(+)-tartaric acid diethyl ester and 3-decen-5-one, 4-methyl, (E). This outcome can pave the way for using Z. mobilis in baking goods, providing innovation possibilities in the area of yeast-free leavened products
Can Zymomonas mobilis Substitute Saccharomyces cerevisiae in Cereal Dough Leavening?
No full textBaker’s yeast intolerance is rising among Western populations, where Saccharomyces cerevisiae is spread in fermented food and food components. Zymomonas mobilis is a bacterium commonly used in tropical areas to produce alcoholic beverages, and it has only rarely been considered for dough leavening probably because it only ferments glucose, fructose and sucrose, which are scarcely present in flour. However, through alcoholic fermentation, similarly to S. cerevisiae, it provides an equimolar mixture of ethanol and CO2 that can rise a dough. Here, we propose Z. mobilis as a new leavening agent, as an alternative to S. cerevisiae, overcoming its technological limit with different strategies: (1) adding glucose to the dough formulation; and (2) exploiting the maltose hydrolytic activity of Lactobacillus sanfranciscensis associated with Z. mobilis. CO2 production, dough volume increase, pH value, microbial counts, sugars consumption and ethanol production were monitored. Results suggest that glucose addition to the dough lets Z. mobilis efficiently leaven a dough, while glucose released by L. sanfranciscensis is not so well fermented by Z. mobilis, probably due to the strong acidification. Nevertheless, the use of Z. mobilis as a leavening agent could contribute to increasing the variety of baked goods alternative to those leavened by S. cerevisiae
Mild pretreatments to increase fructose consumption in saccharomyces cerevisiae wine yeast strains
No full textThe present research investigates the effect of different pretreatments on glucose and fructose consumption and ethanol production by four Saccharomyces cerevisiae wine strains, three isolated and identified from different wine regions in Turkey and one reference strain. A mild stress temperature (45 °C, 1 h) and the presence of ethanol (14% v/v) were selected as pretreatments applied to cell cultures prior to the fermentation step in synthetic must. The goodness fit of the mathematical models was estimated: linear, exponential decay function and sigmoidal model were evaluated with the model parameters R2 (regression coefficient), RMSE (root mean square error), MBE (mean bias error) and χ2 (reduced Chi-square). Sigmoidal function was determined as the most suitable model with the highest R2 and lower RMSE values. Temperature pretreatment allowed for an increase in fructose consumption rate by two strains, evidenced by a t90 value 10% lower than the control. One of the indigenous strains showed particular promise for mild temperature treatment (45 °C, 1 h) prior to the fermentation step to reduce residual glucose and fructose in wine. The described procedure may be effective for indigenous yeasts in preventing undesirable sweetness in wines
Emulsifying and foaming properties of a hydrophobin-based food ingredient from Trichoderma reesei: A phenomenological comparative study
No full textThe aim of this study was the production of a hydrophobin-based food ingredient (HFB) from submerged cultures of Trichoderma reesei and the evaluation of its technological properties in comparison with milk whey (WPC) and egg white (EWP) proteins, widely used in foods for their surface-active properties. T. reesei culture medium was formulated without proteins to ease HFB recovery. Culture supernatant after biomass separation was air-bubbled to concentrate HFB at the air-liquid interface, thus reaching a recovery yield of 138 mg/L. HFB, WPC and EWP solutions (1–5 g/L) were used to test the emulsifying activity index (EAI), the creaming stability (CS) and the foaming properties. EAI was almost four times higher than that of WPC and EWP. Also CS was improved in the case of HFB-stabilized emulsions, but only at the lowest concentration. The overrun of the foam obtained with HFB solutions was 1.2–1.9 times higher than that of the foams obtained with the other ingredients; also foam consistency was significantly higher when created with HFB solutions. Overall results indicate that HFB obtained from T. reesei showed interesting and promising technological properties, paving the way to possible applications in aerated foods and foamed emulsions
Characterization of two zymomonas mobilis wild strains and analysis of populations dynamics during their leavening of bread-like doughs
No full textTwo Zymomonas mobilis wild strains (UMB478 and 479) isolated from water kefir were characterized for their biomass production levels and leavening performance when used as the inoculum of a real bread-like dough formulation. The obtained baked product would be consumable by people with adverse responses to Saccharomyces cerevisiae. In liquid cultures, the two strains reached similar biomass concentration (0.7 g CDW/L). UMB479 showed an interesting resistance to NaCl (MBC 30 g/L), that may be useful in the bakery sector. When inoculated in doughs, UMB479 produced the maximum dough volume (650 mL) after 5 h, glucose was almost consumed and 1 g/100 g of ethanol produced, +200% respective to UMB478. Using S. cerevisiae for comparison purposes, the dough doubled its volume fast, in only 2 h, but reached a final level of 575 mL, lower than that achieved by Z. mobilis. The analysis of bacterial and fungal population dynamics during dough leavening was performed through the Automated Ribosomal Intergenic Spacer Analysis (ARISA); doughs leavened by UMB479 showed an interesting decrease in fungal richness after leavening. S. cerevisiae, instead, created a more complex fungal community, similar before and after leavening. Results will pave the way for the use of Z. mobilis UMB479 in commercial yeast-free leavened products
The thermal physiology of the ruminant fetus
No full textThe chapter, "The thermal physiology of the ruminant fetus" was written by the listed authors including Alida Faurie (Douglas College Faculty). This volume contains 26 chapters in sections on regulation of feed intake, rumen microbiology and fermentation, nutrient absorption and splanchnic metabolism, tissue maintenance and utilization of endogenous body reserves, tissue growth, reproduction, pregnancy and lactation, ruminant physiology and genetics, and host resistance to parasites and pathogens. The chapters are the plenary papers presented at the IX International Symposium on Ruminant Physiology in Pretoria, South Africa during October 1999.
This chapter discusses the fetal body temperature homeostasis, feto-maternal thermal relationship, birth-related changes in body temperatures, and preterm labour and abortion in ewes.book chapterPublished
Mapping an Atlantic world: circa 1500/ Alida C. Metcalf.
No full text"The year 1500, Metcalf argues, was a turning point in Europeans' understanding of their world in relation to the Atlantic Ocean. In the sixteenth century, cartographers began to conceptualize-and present to the public-an interconnected Atlantic World that was open and navigable, in contrast with the mysterious ocean that had blocked off the Western hemisphere before Columbus. The author contends that early modern cartographers were significant agents in the intellectual history of the Atlantic World"--The Atlantic Ocean on the periphery -- 1500 -- Chartmakers -- The fourth part of the world -- Parrots and trees -- The cannibalist scene.1 online resourc
Correction to: A mixed methods analysis of the medication review intervention centered around the use of the ‘Systematic Tool to Reduce Inappropriate Prescribing’ Assistant (STRIPA) in Swiss primary care practices (BMC Health Services Research, (2024), 24, 1, (350), 10.1186/s12913-024-10773-y)
No full textIn this article, the author name Corlina Johanna Alida Huibers was incorrectly written as Johanna Alida Corlina Huibers due to a typesetting mistake. The author group has been updated above and the original article has been corrected. The publisher apologises to the authors and readers for the inconvenience caused by this error
Correction: A mixed methods analysis of the medication review intervention centered around the use of the ‘Systematic Tool to Reduce Inappropriate Prescribing’ Assistant (STRIPA) in Swiss primary care practices (BMC Health Services Research, (2024), 24, 1, (350), 10.1186/s12913-024-10773-y)
No full textIn this article, the author name Corlina Johanna Alida Huibers was incorrectly written as Johanna Alida Corlina Huibers due to a typesetting mistake. The author group has been updated above and the original article has been corrected. The publisher apologises to the authors and readers for the inconvenience caused by this error
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