Dry Yeast Research Articles

Calcium Carbonate in Bio-Based Material and Factor Affecting Its Precipitation Rate for Repairing Concrete

The use of bio-based material for repairing concrete is a relatively new method. Therefore, more results from simulated real-condition experiments are needed before being applied on a practical scale. In the recent past, several studies have been conducted on the improvement of bio-based repair materials. In this study, the bio-based material involving yeast, glucose, and calcium acetate mixed in a Tris buffer solution showed the potential to develop a microbial process leading to the precipitation of calcium carbonate. We investigated the factors affecting the precipitation rate of the calcium carbonate of bio-based materials for repairing leakage in the concrete specimens. Based on a series of experiments involving temperature, the type of dry yeast, and the concentration of the Tris buffer solution, the composition of bio-based materials with the highest precipitation rate of calcium carbonate was selected. The selected mixture could be applied to repair leakage of concrete until the cracks are sealed entirely.

Mineralization induced by phosphorylated dry baker's yeast.

We found the mineralization of Cu during long-term Cu2+ adsorption onto dry baker’s yeast cells phosphorylated using sodium cyclo-triphosphate. Field emission scanning electron microscopy (FESEM) with energy-dispersive X-ray spectroscopy confirmed that the elemental composition of minerals were copper, phosphorus, and oxygen. Synchrotron-based X-ray absorption fine structure showed that the local structure around Cu atoms deposited on the mineral was almost identical to that of commercial copper (II) phosphate Cu3(PO4)2∙3H2O. However, the crystallinity was low, and the structure was slightly distorted. Time profile analysis using FESEM revealed that copper phosphate mineralization was first apparent on Day 3 of adsorption, whereas mineral formation plateaued at around Day 7. It seems that mineralization occurs by the local saturation of phosphate and Cu2+ on the yeast cells. Mineralization of the rare earth ion Dy3+ was also demonstrated during long-term adsorption. Mineralization on phosphorylated yeast cells appears to follow a common path for various types of metal ions and provides a promising technique for metal recovery via irreversible adsorption.

The aroma compounds of Chinese steamed bread fermented with sourdough and instant dry yeast

The aroma-active compounds of yeast-CSB (Chinese steamed bread) and sourdough-CSB were studied. Aroma compounds were characterized using the flavor dilution (FD) factor, calculation of odor active value (OAV), partial least squares regression (PLSR) correlation analysis and aroma recombination. Sensory evaluation was also done to provide an aroma profile of different CSB. The 2-pentylfuran (wheat-like), 1-octen-3-ol (mushroom), ethyl lactate (floral) and benzaldehyde (almond) showed the largest FD factors in sourdough-CSB. While in yeast-CSB, the FD factors of 2-pentylfuran, 2-methyl-1-propanol (alcoholic), hexanal (green), 1-octen-3-ol and nonanal (citrus) were highest. The main differences between the two CSB were attributed to the concentration of 2-pentylfuran and 1-octen-3-ol with high FD factors. In addition, ethyl lactate found in sourdough-CSB contributed to the floral odor, while 2-methyl-1-propanol found in yeast-CSB contributed to the strong alcoholic odor. This study could provide a better understanding of the factors affecting the aroma profile of CSB.

Comparison of Durability of Gaziantep Village Cookies Prepared With Chickpea Yeast and Dry Yeast by Using Sensory Evaluation Test

Gaziantep village cookies, which was patented as Geographical Indicated Product category by Turkish Patent Institute on 28.12.2017, is originally produced with chickpea yeast. However production steps of chickpea yeast are difficult and therefore many producers use dry yeast. In this study, the durability of chickpea and dry yeast-produced Gaziantep Village Cookies was compared by using sensory test. The same recipe was used in cookies prepared with dry and chickpeas yeast. Only yeast are different. Recipe was formed by interviewing with 10 women (over the 50 years old) born and bred in Gaziantep. The taste, color, odor and hardness of these cookies were evaluated sensitively for every 15 days during 2,5 months. Hedonic scale analysis was performed with semi-trained panelist. The results of the sensory tests were statistically evaluated by using the One-way ANOVA test in SPSS 15.0 (Version 2.0). It has been seen that time (p>0.05) is not an important factor for taste, color, odor and hardness of cookies made with chickpea yeast. It has been observed that time (p>0.05) is not an important factor for taste and color of cookies made with dry yeast but time is an important factor for odor and hardness of these cookies (p<0.05) Keyword : Gaziantep, village, cookies, chickpea, dry, yeast. DOI : 10.7176/JSTR/6-10-03

Synthesis of ethyl (R)-4-chloro-3-hydroxybutyrate by immobilized cells using amino acid-modified magnetic nanoparticles

Fe3O4-Arg was selected as the optimal carrier due to its high activity recovery of immobilized cells in the preparation of Fe3O4-Arg-Cells. The optimal immobilization conditions for the preparation of Fe3O4-Arg-Cells were 30 °C, 4 h, pH 7, and 3 g dry yeast. The activity recovery of immobilized cells reached 76.8 %. For a batch reduction in a shaker in an alternating magnetic field, Fe3O4-Arg-Cells were used as a catalyst to gain ethyl (R)-4-chloro-3-hydroxybutyrate ((R)-CHBE). For further improvement in reduction productivity, a continuous reduction in the magnetic fluidized bed reactor system (MFBRS) was completed. Under their optimal transformation conditions, it took 24 h for Fe3O4-Arg-Cells to complete the conversion of ethyl 4-chloro-3-oxobutanoate (COBE) (0.8553 mol/L) in the shaker and only 8 h for the batch reduction in an alternating magnetic field. Continuous reduction in MFBRS provided new ideas for the efficient production of (R)-CHBE; 1.5882 mol/L (10 mL) of COBE can be completely converted in 6 h. The conversion and enantiomeric excess (e.e.) of (R)-CHBE were 100 % and above 99.9 % respectively, in the three reaction systems mentioned above.

Sensory and Physicochemical Characterization of Sourdough Bread Prepared with a Coconut Water Kefir Starter.

There is a recognized need for formulating functional food products using selected lactic acid bacteria (LAB) starter cultures from various sources such as kefir, yoghurt or kombucha that have health benefits. The principle objective of this study was to investigate the use of a coconut water kefir-based fermentation starter culture using Lactobacillus fermentum and Lactobacillus plantarum to develop a sourdough bread. Check-all-that-apply (CATA) sensory profiling was used in this study to evaluate the sensory profile of sourdough breads that varied with culture type, culture concentrations, with and without added yeast, and with fermentation for 18 and 24 h. Based on correspondence analysis (CA) of the CATA results, bread samples with positive sensory attributes were chosen for further physicochemical analysis. Physicochemical analyses (texture, proximate composition, shelf life, carboxylic acid analysis and amino acid analysis) were carried out on breads formulated with starter culture concentrations of 8.30 log CFU/mL of L. fermentum, 4.90 log CFU/mL of L. fermentum and 9.60 log CFU/mL of L. plantarum, each fermented for 24 h without baker’s yeast. The bread sample that was formulated with a coconut water kefir (CWK) starter culture containing 9.60 log CFU/mL of L. plantarum, without dry yeast and fermented for 24 h, had significantly higher values for almost all amino acids and a lower protein content compared to samples formulated using CWK cultures containing 8.30 log CFU/mL of L. fermentum and 4.90 log CFU/mL of L. fermentum, both without dry yeast and fermented for 24 h. The bread sample formulated with CWK starter culture containing 9.60 log CFU/mL of L. plantarum, without dry yeast and fermented for 24 h, also produced significant quantities of organic acids (pyruvic acid, acetic acid, lactic acid and succinic acid). These changes in the physicochemical properties can improve overall bread quality in terms of flavor, shelf life, texture and nutritional value.

Effect of Stand-Alone and Combined Ultraviolet and Ultrasound Treatments on Physicochemical and Microbial Characteristics of Pomegranate Juice

The objective of this study was to determine the combined usage possibilities of ultraviolet (UV) and ultrasonic (US) processes in the pasteurization of pomegranate juice. For this purpose, UV, US, and combined UV+US pasteurization of pomegranate juice were optimized using experimental designs, such as the Central Composite Design (CCD) and Factorial Design (FD), and compared with the conventional pasteurization process. Total phenolic content (TPC), color a*, water-soluble dry matter (°Brix), turbidity, anthocyanin, DPPH, HPLC TPC, and yeast and mold count were used as quality parameters during all of the processes. The results showed that the application of 50 °C, 3.5 L/min flow rate and 5.1 mW/cm2 UV dose, and 10 min US (200 Watt) together reduced the microbial population below the detection limits. The integration of UV+US processes into the pasteurization process could limit microbial activity at lower temperatures and times than the conventional pasteurization process, thus preserving the existing bioactive compounds.

Effects of different starter cultures on the quality characteristics and shelf-life of fermented rice cake.

The effects of Makgeolli, dry yeast (DY), sourdough with dry yeast (SDDY) and sourdough with Makgeolli (SDMG) on the quality of fermented rice cakes (FRCs) stored at 23°C for 3days were determined. The acidity of SDDY and SDMG significantly increased with increasing fermentation time. The FRCs supplemented with sourdough had slightly higher moisture contents than others. The addition of DY and SDDY increased the specific volume of the FRC, in which its texture was softer. The addition of DY and sourdoughs significantly decreased the firming rate of crumb and improved the sensory qualities. The sourdoughs retarded amylopectin retrogradation, indicating their anti-staling effect on the FRC. Compared to the control, the shelf-lives of FRCs made with DY and SDDY were extended by 0.7 and 0.5days based on the instrumental hardness, respectively. DY and SDDY effectively improved the appearance and texture of FRC and extended its shelf-life.

Some Agronomical Practices for Improving Growth ,Yield and Quality of Pea Growing at Late Seasons. بعض الممارسات الزراعیة لتحسین النمو والمحصول والجودة للبسلة المنزرعة فی العروات المتأخرة

This work was carried out at the Experimental Farm of El-Baramoon Research Station, Horticulture Research Institute, Agricultural Research Center, during the late winter season of 2018 and 2019 to study the effect of two sowing dates (20th January and 20th February), foliar applications, i.e., brassinolide (5 and10 mg/l), mixture of growth regulator (0.5 and 1cm/l), dry yeast extract (5 and 10gm/l) potassium nitrate (1 and 2 gm/l) and potassium silicate (2.5 and 5gm/l) in addition to vernalization practice and their interactions on growth, yield and its components characteristics of pea cv. Master- B.The obtained results revealed that, the first sowing date induced a higher growth values , yield and its components and chemical composition of seeds compared with the second sowing date. Spraying brassinolide at 10 mg/l gave the highest growth, yield and chemical components of pea plants, followed by potassium nitrate at 2gm/l, growth regulators mixture at 1cm/l and yeast extract at 10gm/l. Sowing pea seeds in 20th January and spraying with brassinolide at 10 mg/l introduced the best interaction with respect to growth, yield components and chemical composition of seeds. From the obtained results it could be recommended that sowing pea in 20th January and spraying with brassinolide (10 mg/l) and/or potassium nitrate at 2gm/l, and/or growth regulators mixture at 1cm/l and/or yeast extract at 10 gm/l improved growth, yield and chemical composition of pea growing at late season conditions .

Agroindustrial Byproducts for the Generation of Biobased Products: Alternatives for Sustainable Biorefineries

The integrated approach in biorefinery mainly involves the utilization of various agroindustrial byproducts as raw materials for the production of several biobased products like biofuels, bioenergy, and other high-value chemicals. Biofuels are the backbone of biorefineries, however, production of value-added biomolecules such as biopigments, biopolymers, biosurfactants, nutritional yeast, etc. have been atracting a great attention. The production of these biomolecules using traditional approaches have been extensively studied in last few years due to their promising application in different industries such as chemical, food/feed, and pharmaceutical for the development of novel products for mankind. Moreover, the production of such biomolecules using lignocellulosic, starchy and some other agroindustrial byproducts is still not fully explored. Hence, there is a huge scope in the development of sustainable biorefining approaches to make the technology cost-effective. The lignocellulosic biomasses usually used in biorefineries are mainly composed of cellulose, hemicellulose, and lignin, whereas starchy materials, besides starch, usually contain, protein, lipids and some micronutrients. The processing of these biomasses through successive steps like pretreatments, enzymatic hydrolysis and fermentation is essentially required to obtained final biobased products. Considering certain bottlenecks of above-mentioned conventional biorefineries approaches, new technologies have been proposed for the improved pretreatment of biomass and efficient enzymatic hydrolysis in order to minimize the concentration of toxic inhibitors in resulting hydrolysate. In this review, we highlighted on different agroindustrial byproducts and their applications for the production of valuable biorefinery products.

Structure and function of yeast Lso2 and human CCDC124 bound to hibernating ribosomes.

Cells adjust to nutrient deprivation by reversible translational shutdown. This is accompanied by maintaining inactive ribosomes in a hibernation state, in which they are bound by proteins with inhibitory and protective functions. In eukaryotes, such a function was attributed to suppressor of target of Myb protein 1 (Stm1; SERPINE1 mRNA-binding protein 1 [SERBP1] in mammals), and recently, late-annotated short open reading frame 2 (Lso2; coiled-coil domain containing short open reading frame 124 [CCDC124] in mammals) was found to be involved in translational recovery after starvation from stationary phase. Here, we present cryo-electron microscopy (cryo-EM) structures of translationally inactive yeast and human ribosomes. We found Lso2/CCDC124 accumulating on idle ribosomes in the nonrotated state, in contrast to Stm1/SERBP1-bound ribosomes, which display a rotated state. Lso2/CCDC124 bridges the decoding sites of the small with the GTPase activating center (GAC) of the large subunit. This position allows accommodation of the duplication of multilocus region 34 protein (Dom34)-dependent ribosome recycling system, which splits Lso2-containing, but not Stm1-containing, ribosomes. We propose a model in which Lso2 facilitates rapid translation reactivation by stabilizing the recycling-competent state of inactive ribosomes.

Semi-continuous pilot-scale microbial oil production with Metschnikowia pulcherrima on starch hydrolysate

BackgroundHeterotrophic microbial oils are potentially a more sustainable alternative to vegetable or fossil oils for food and fuel applications. However, as almost all work in the area is conducted on the laboratory scale, such studies carry limited industrial relevance and do not give a clear indication of what is required to produce an actual industrial process. Metschnikowia pulcherrima is a non-pathogenic industrially promising oleaginous yeast which exhibits numerous advantages for cost-effective lipid production, including a wide substrate uptake, antimicrobial activity and fermentation inhibitor tolerance. In this study, M. pulcherrima was fermented in stirred tank reactors of up to 350 L with 250-L working volume in both batch and semi-continuous operation to highlight the potential industrial relevance. Due to being food-grade, suitable for handling at scale and to demonstrate the oligosaccharide uptake capacity of M. pulcherrima, enzyme-hydrolysed starch in the form of glucose syrup was selected as fermentation feedstock.ResultsIn batch fermentations on the 2-L scale, a lipid concentration of 14.6 g L−1 and productivity of 0.11 g L−1 h−1 were achieved, which was confirmed at 50 L (15.8 g L−1; 0.10 g L−1 h−1). The maximum lipid production rate was 0.33 g L−1 h−1 (daily average), but the substrate uptake rate decreased with oligosaccharide chain length. To produce 1 kg of dry yeast biomass containing up to 43% (w/w) lipids, 5.2 kg of the glucose syrup was required, with a lipid yield of up to 0.21 g g−1 consumed saccharides. In semi-continuous operation, for the first time, an oleaginous yeast was cultured for over 2 months with a relatively stable lipid production rate (around 0.08 g L−1 h−1) and fatty acid profile (degree of fatty acid saturation around 27.6% w/w), and without contamination. On the 250-L scale, comparable results were observed, culminating in the generation of nearly 10 kg lipids with a lipid productivity of 0.10 g L−1 h−1.ConclusionsThe results establish the importance of M. pulcherrima for industrial biotechnology and its suitability to commercially produce a food-grade oil. Further improvements in the productivity are required to make M. pulcherrima lipid production industrial reality, particularly when longer-chain saccharides are involved.

Production of yeast hydrolysates by Bacillus subtilis derived enzymes and antihypertensive activity in spontaneously hypertensive rats

ABSTRACT Numerous studies have been carried out on antihypertensive peptides. However, the separation and purification were too costly, limiting their industrial application. The aim of this study was to produce antihypertensive yeast hydrolyzates (YH) with a simple and cost-saving procedure, coupling fermentation and enzymatic hydrolysis. Crude enzyme, exhibiting protease and β-glucanase activities, was generated from Bacillus subtilis Hu 528 and subsequently used to release and hydrolyze the intracellular proteins from dry yeast. YH exhibited strong ACE inhibitory activity, with IC50 value of 26.13 μg/mL, while antihypertensive properties were found on spontaneously hypertensive rats (SHRs) in short- and long-term administrations. YH could increase blood nitric oxide (NO) of SHRs. Moreover, 778 peptides were identified from YH by Nano LC-MS/MS and most of these peptides had ACE inhibitory potentials based on database search and alignment. This study indicated promising potential of YH as a source of ACE inhibitory peptides and potentially could be used in functional foods.

Use of precision-fed cecectomized rooster assay and digestible indispensable amino acid scores to characterize plant- and yeast-concentrated proteins for inclusion in canine and feline diets.

Increased consumer interest in high-quality and novel protein sources has driven the demand for the inclusion of protein-rich ingredients in companion animal diets. Novel protein concentrates, with protein contents of at least 50%, have been used to satisfy these consumer demands. However, minimal information is available regarding the macronutrient composition and protein quality of these ingredients that is needed for proper formulation of pet foods. Therefore, the objectives of this study were to determine the macronutrient and amino acid compositions, standardized amino acid digestibility according to the precision-fed rooster assay, and protein quality using digestible indispensable amino acid score (DIAAS like) of pea protein (PP), potato protein (POP), faba bean protein (FBP), soy protein concentrate (SPC), and dried yeast (DY). Precision-fed rooster assays were conducted using cecectomized roosters to calculate standardized amino acid digestibility and true metabolizable energy corrected for nitrogen (TMEn). For all five protein concentrates, all essential amino acids were highly digestible (88.0% to 96.3%, dry matter basis) with differences (P < 0.05) in only lysine, methionine, and tryptophan digestibilities. The TMEn values were highest for POP (4.22 kcal/g) and DY (3.61 kcal/g). The DIAAS-like values for adult dogs indicated that methionine was the first-limiting amino acid in all protein concentrates except POP, where the first-limiting amino acid was tryptophan. Using Association of American Feed Control Officials (AAFCO)-recommended values for adult cats, DIAAS-like values for methionine were lowest (P < 0.05) for FBP at 81.5%, with all other amino acids for all protein concentrates over 100%. The National Research Council (NRC)-recommended allowances for adult cats indicated that DIAAS-like methionine values for PP (92.7%) and FBP (73.8%) were significantly lower (P < 0.05) with these being the first-limiting amino acids, with the remaining amino acids above 100% for the other protein concentrates. The protein quality and high essential amino acid digestibility of these protein concentrates indicate that they would be viable protein sources in canine and feline diets. However, additional complementary protein sources should be included to meet the requirements of all essential amino acids.

Valorization of Zymomonas mobilis for bioethanol production from potato peel: fermentation process optimization

In this study, Zymomonas mobilis was used to produce bioethanol from potato peel (PP) wastes. For this purpose, enzymatic hydrolysis was first performed on potato peel to release the fermentable sugars. Then, the effect of enzyme dosages and solid loading was investigated on the hydrolysis process. Following the hydrolysis step, to evaluate the ability of Z. mobilis in bioethanol production from PP, the effects of five important factors (initial sugar concentration, bacterial dry weight, peptone and yeast extract weights, and fermentation time) were studied, after which the factors were optimized using response surface methodology (RSM) experimental design. It was observed that a maximum of 88.2 g/l reducing sugar was produced using 50 U α-amylase and 12 U amyloglucosidase with 20%PP solid loading. The optimized conditions for fermentation step were as follows: 61.3 g/l initial sugar, 0.024 g bacterial dry cell, 0.35 g meat peptone, 0.35 g yeast extract, and 31-h fermentation time. The maximum ethanol concentration of 23.3 ± 0.015 g/l was produced under the optimum conditions. Time courses of ethanol production and sugar consumption were also studied, revealing consumption of 78.9% of initial sugars under optimum conditions.

The “pied de cuve” as an alternative way to manage indigenous fermentation: impact on the fermentative process and &lt;i&gt;Saccharomyces cerevisiae&lt;/i&gt; diversity

Winemakers are increasingly keen to limit the use of commercial yeasts in order to reduce oenological inputs. The preparation of an indigenous winery-made fermentation starter from grapes called ‘pied de cuve’ (PdC) is becoming popular, especially in organic farming systems. However, the implementation of the PdC method is still empirical and knowledge is lacking regarding the impact of PdC on S. cerevisiae diversity during alcoholic fermentation. In this study, the impact of PdC on S. cerevisiae genetic diversity and wine composition was evaluated at an industrial scale. Despite very low initial population level of S. cerevisiae before inoculation, the use of PdC was as efficient as Active Dry Yeast in terms of fermentation kinetics and chemical analyses on the resulting wines, except for one modality. At mid-fermentation, the diversity of S. cerevisiae strains was different depending on the PdC used, and was also different from that in the spontaneous fermentation with, in some cases, clonal expansion. Our results provide evidence that the use of PdC could secure the fermentation process more efficiently than spontaneous fermentation.

The "pied de cuve" as an alternative way to manage indigenous fermentation: impact on the fermentative process and Saccharomyces cerevisiae diversity

Winemakers are increasingly keen to limit the use of commercial yeasts in order to reduce oenological inputs. The preparation of an indigenous winery-made fermentation starter from grapes called ‘pied de cuve’ (PdC) is becoming popular, especially in organic farming systems. However, the implementation of the PdC method is still empirical and knowledge is lacking regarding the impact of PdC on S. cerevisiae diversity during alcoholic fermentation. In this study, the impact of PdC on S. cerevisiae genetic diversity and wine composition was evaluated at an industrial scale. Despite very low initial population level of S. cerevisiae before inoculation, the use of PdC was as efficient as Active Dry Yeast in terms of fermentation kinetics and chemical analyses on the resulting wines, except for one modality. At mid-fermentation, the diversity of S. cerevisiae strains was different depending on the PdC used, and was also different from that in the spontaneous fermentation with, in some cases, clonal expansion. Our results provide evidence that the use of PdC could secure the fermentation process more efficiently than spontaneous fermentation.

Basal catalase activity and high glutathione levels influence the performance of non-Saccharomyces active dry wine yeasts

Non-Saccharomyces wine yeasts are useful tools for producing wines with complex aromas or low ethanol content. Their use in wine would benefit from their production as active dry yeast (ADY) starters to be used as co-inocula alongside S. cerevisiae. Oxidative stress during biomass propagation and dehydration is a key factor in determining ADY performance, as it affects yeast vitality and viability. Several studies have analysed the response of S. cerevisiae to oxidative stress under dehydration conditions, but not so many deal with non-conventional yeasts. In this work, we analysed eight non-Saccharomyces wine yeasts under biomass production conditions and studied oxidative stress parameters and lipid composition. The results revealed wide variability among species in their technological performance during ADY production. Also, for Metschnikowia pulcherrima and Starmerella bacillaris, better performance correlates with high catalase activity and glutathione levels. Our data suggest that non-Saccharomyces wine yeasts with an enhanced oxidative stress response are better suited to grow under ADY production conditions.

Influence of dietary supplementation of yeast on milk composition and lactation curve behavior of Sohagi ewes, and the growth performance of their newborn lambs

Abstract Thirty-nine pregnant Sohagi ewes were divided into three equal groups to investigate the effects of an active dry yeast (Saccharomyces cerevisiae- SC, 2.44 × 1011 CFU/g yeast product) on lactation curve, milk composition, blood components and growth performance of newborn lambs. Ewes in the control group were fed a basal diet without yeast supplementation (SC0), the second (SC5) and third (SC10) groups were fed the basal diet with 5 or 10 g per head/day of SC, respectively. Dry yeast supplementation increased (P 0.05) lactose and ash contents. Compared with the control treatment, total milk yield was improved in SC10 and SC5 by 20.3 and 14.3 %, respectively. Dry yeast supplementation resulted in significant changes (P

The Immunological Reactivity of Turkeys of Different Genotypes on the Action of Environmental Factors

The Immunological Reactivity of Turkeys of Different Genotypes on the Action of Environmental Factors