Types Of Yeast Strains Research Articles

Influence of Yeast Strain on Odor-Active Compounds in Fiano Wine

The type of yeast strain used for wine alcoholic fermentation dramatically affects its final volatile composition and, therefore, its sensory properties. In this study, the influence of four oenological Saccharomyces strains (three S. cerevisiae and one S. bayanus) on wine volatile composition was determined on the Fiano variety, a typical cultivar from the Campania region (Italy), fermented in oak barrique. Fiano wines were analyzed by means of gas chromatography/mass spectrometry (GC/MS) and gas chromatography/olfactometry (GC/O). The results showed that the four selected yeast strains had a significant impact on the majority of volatile compounds as shown by the concentration of volatile compounds and based on the Aroma Extract Dilution Analysis (AEDA) values for many of the odor volatile compounds. This resulted in a dramatic change of the odor impact of the wines, such as the “fruity” attribute, which was higher compared to the control, and caused some changes of other odor attributes, particularly “floral”, “phenolic” and “honey”. This research demonstrates the potential of using these selected yeast strains and this technological approach of oak fermentation for this typical white wine grape variety.

American pale Ale craft beer: Influence of brewer's yeast strains on the chemical composition and antioxidant capacity

This study aimed to evaluate the influence of using four different Saccharomyces cerevisiae strains on the phenolic compounds, antioxidant capacity (AOX), organic acid, sugar, and alcohol profiles of American Pale Ale (APA) craft beer. US-05 yeast presented a lower fermentation capacity but originated a beer with suitable ethanol content, higher lactic acid content, and lower acetic acid and succinic acid contents. Furthermore, it presented higher quantities of catechins and procyanidin B1, which resulted in a higher AOX. M15 yeast originated a beer with lower ethanol content and AOX and higher malic and formic acid contents. Beers made with BRY-97 yeast had higher ethanol content, while those made with S-04 yeast presented higher glycerol content. Several factors can affect beer quality. This study demonstrated that the type of yeast strain used in the APA craft beer brewing has a significant impact not only on the fermentative process but also on the functional characteristics of the products.

Development of sake yeast haploid set with diverse brewing properties using sake yeast strain Hiroshima no. 6 exhibiting sexual reproduction

Among sake yeast strains, Kyokai no. 7 (K7) and its closely related strains (K7 group) are predominantly used because of their excellent brewing properties. In the sake industrial sector, the need for various types of yeast strains is high. Although crossbreeding is an effective method for generating genetic diversity that should result in diverse characteristics, most K7 group strains lack normal sporulation ability, including the ability to undergo meiotic chromosomal recombination, which leads to difficulties in crossbreeding. Accordingly, the improvement of sake yeast strains primarily depends on mutagenesis and suitable selection in a stepwise manner. Our recent study revealed that the long-preserved sake yeast strain Hiroshima no. 6 (H6) does not belong to the K7 group despite genetically being extremely similar. In addition, H6 exhibited normal sporulation. Thus, we isolated haploid cells from H6 and mated them with previously isolated haploid cells of K7 group strains. The crossbred diploid strains had normal sporulation ability; hence, we performed tetrad analysis. The brewing characteristics of the obtained haploid set were extremely diverse. Principal component analysis based on the volatile and organic acid components measured using small-scale sake brewing tests revealed that the haploid strains derived from each diploid strain displayed a characteristic distribution. Thus, we demonstrated the availability of genetic crossbreeding using H6 with sporulation ability to facilitate both the development of novel sake yeast strains with many desirable characteristics and analyses of the function of sake yeast.

Comparison of malachite green adsorption by two yeast strains using Raman microspectroscopy.

Malachite green (MG), as a triarylmethane compound, poses a health hazard and causes considerable environmental concern. In this work, batch biosorption experiments were conducted under different operational conditions such as pH, contact time and adsorption dose to assess the optimal parameters of MG dye removal by yeast biomass from aqueous solutions. Then, the conventional biochemical assay was used to evaluate MG removal efficiency (75.18 and 95.85%) by Saccharomyces cerevisiae and Candida utilis. In addition, Fourier-transform infrared spectroscopy in combination with Raman microspectroscopy was employed to scrutinize the differences of dye removal between two types of yeast strains. This study demonstrates that Raman microspectroscopy may serve as a useful and powerful tool to quantitatively measure the content of MG dye on yeast cell surfaces in situ, and even offer an alternative new technique to seek potentially proper adsorbents for the removal of toxic dyes from industrial effluents.

Novel method for detecting and quantifying phenol with transient response of glycolytic oscillations of synchronised yeast cells

Yeast displays cyclic changes of autofluorescence of NADH in living, metabolising cells, known as glycolytic oscillations. In this study, we have demonstrated the proof of concept for exploiting this mechanism for a novel oscillation-based biosensor. The metabolism of Sacharomyces cerevisae BY4742 cells were synchronised and treated with various concentrations of phenol and with glucose and nitrobenzene additions for comparison. The established method allowed detection of phenol within 0.6–26.6 mM concentration range resulting in signal frequency of 0.29–2.03*10−2 Hz, correspondingly. The analysed frequency was negatively and linearly correlated with phenol concentration (R = 0.98). Positive (glucose) and negative (nitrobenzene) control did not caused significant oscillations indicating selectivity of the proposed mechanism. The proposed method is fast (27 min), easy to conduct and can be performed also with other types of yeast strains which makes it accessible for application with local strains and in developing countries. This is the first time, when the natural oscillatory mechanism of yeasts was demonstrated for the biosensing purposes.

Bread Dough and Baker's Yeast: An Uplifting Synergy.

Yeast-mediated dough fermentation is an important phase in the bread making process. The fermentative performance of yeast cells during fermentation is of critical importance for final bread quality, since yeast cells produce CO2 and other metabolites that have an influence on dough rheology and bread texture, volume, and taste. Different factors affect the fermentative performance of yeast cells during dough fermentation, including dough ingredients, fermentation conditions, the type of yeast strain used and yeast pregrowth conditions. Bread dough is a complex matrix that contains several ingredients that can affect the fermentation rate of yeast cells. Although the individual effects of sugar availability and salt level on the leavening ability of yeast have been studied extensively, a comprehensive overview of the relationship between bread dough constituents, fermentation conditions and yeast functionality is still lacking. Moreover, the dough environment is highly variable as several types of dough like lean, sweet or frozen doughs are currently produced by commercial bread producers. For optimal fermentation rates in different types of dough, the use of appropriate yeast strains with specific phenotypic traits is required. Therefore, many researchers have focused on the improvement of yeast strains for optimal fermentation in different types of dough like lean, sweet or frozen dough. Against this background, this review summarizes the current knowledge on the interaction between bread dough and baker's yeast and how to improve this interaction, thereby providing a useful background for further research concerning the functionality of yeast in bread dough.

토마토 농축액을 이용한 무가당 알코올 발효를 위한 효모의 선발

The purpose of this study was to screen desirable yeast strains for alcoholic fermentation of tomato paste without sugar addition. The moisture, crude protein, crude fat, ash, and soluble nitrogen contents of the tomato paste (25 °Brix) were found to be 67.33%, 1.90%, 0.03%, 0.02%, and 30.72%, respectively. Free sugars found in the paste were fructose and glucose. Most abundant free amino acids of the paste were glutamic, aspartic, and γ-aminobutyric acids. Total seven yeast strains (Saccharomyces cerevisiae KDH (TWA), S. cerevisiae Lalvin ICVD-47 (TWB), S. cerevisiae Lalvin RC-212 (TWC), S. cerevisiae Lalvin K1-V1116 (TWD), S. bayanus Lalvin EC-1118 (TWE), S. cerevisiae Enoferm (TWF), and S. cerevisiae DJ97(KCTC8842P) (TWG)) were tasted for alcohol fermentation of the tomato paste. The highest alcohol content (8.2%) and the lowest residual sugar content (13.25 °Brix) were observed in the tomato paste fermented using the S. cerevisiae Lalvin ICVD-47 strain (TWB) after 3 day and 4 day of fermentation, respectively. Sugar and reducing sugar contents, and pH of the tomato paste were not remarkably affected by the difference in yeast strains used, showing 13.25~13.45 °Brix, 28.37~28.48 mg/mL, and 4.43~4.54, respectively, after 4 day of fermentation. Color and total acid content were significantly affected by the types of yeast strains and fermentation time, but the numerical changes were negligible. These results indicate that TWB would be the suitable strain for alcoholic fermentatiom of tomato paste based on its highest alcohol production and the lowest residual sugar content produced during fermentation.

Brewer's Yeast as a New Source of Palmitoleic Acid—Analysis of Triacylglycerols by LC–MS

AbstractWe identified both fatty acids and TAG in waste yeast from seven breweries employing both top and bottom fermentation. Brewer′s yeast was found to contain FA exhibiting a broad range of acyl chain lengths, with a high proportion of the nutritionally and biotechnologically important palmitoleic acid. Analysis of FA by GC–MS and of TAG by LC–MS with APCI provided information on the type of brewer′s yeast and technology of fermentation. The composition of TAG containing major FA such as palmitic, palmitoleic and oleic acid was found to depend not only on the type of yeast strain, i.e. Saccharomycespastorianus or S. cerevisiae, but also on brewing fermentation process, i.e. top versus bottom fermentation. Top and bottom yeast can readily be distinguished by the ratios of some regioisomers of TAG since, e.g., the ratio of regioisomers PoOPo and PoPoO is always >1 in top fermenting yeast and <1 in bottom yeast. The ratios can thus be used as markers for determining the yeast type and beer‐producing technology in a given brewery.

Chlorine dioxide against bacteria and yeasts from the alcoholic fermentation

The ethanol production in Brazil is carried out by fed-batch or continuous process with cell recycle, in such way that bacterial contaminants are also recycled and may be troublesome due to the substrate competition. Addition of sulphuric acid when inoculum cells are washed can control the bacterial growth or alternatively biocides are used. This work aimed to verify the effect of chlorine dioxide, a well-known biocide for bacterial decontamination of water and equipments, against contaminant bacteria (Bacillus subtilis, Lactobacillus plantarum, Lactobacillus fermentum and Leuconostoc mesenteroides) from alcoholic fermentation, through the method of minimum inhibitory concentration (MIC), as well as its effect on the industrial yeast inoculum. Lower MIC was found for B. subtilis (10 ppm) and Leuconostoc mesenteroides (50 ppm) than for Lactobacillus fermentum (75 ppm) and Lactobacillus plantarum (125 ppm). Additionally, these concentrations of chlorine dioxide had similar effects on bacteria as 3 ppm of Kamoran® (recommended dosage for fermentation tanks), exception for B. subtilis, which could not be controlled at this Kamoran® dosage. The growth of industrial yeasts was affected when the concentration of chlorine dioxide was higher than 50 ppm, but the effect was slightly dependent on the type of yeast strain. Smooth yeast colonies (dispersed cells) seemed to be more sensitive than wrinkled yeast colonies (clustered cells/pseudohyphal growth), both isolated from an alcohol-producing unit during the 2006/2007 sugar cane harvest. The main advantage in the usage of chlorine dioxide that it can replace antibiotics, avoiding the selection of resistant populations of microorganisms.

Chlorine dioxide against bacteria and yeasts from the alcoholic fermentation

The ethanol production in Brazil is carried out by fed-batch or continuous process with cell recycle, in such way that bacterial contaminants are also recycled and may be troublesome due to the substrate competition. Addition of sulphuric acid when inoculum cells are washed can control the bacterial growth or alternatively biocides are used. This work aimed to verify the effect of chlorine dioxide, a well-known biocide for bacterial decontamination of water and equipments, against contaminant bacteria (Bacillus subtilis, Lactobacillus plantarum, Lactobacillus fermentum and Leuconostoc mesenteroides) from alcoholic fermentation, through the method of minimum inhibitory concentration (MIC), as well as its effect on the industrial yeast inoculum. Lower MIC was found for B. subtilis (10 ppm) and Leuconostoc mesenteroides (50 ppm) than for Lactobacillus fermentum (75 ppm) and Lactobacillus plantarum (125 ppm). Additionally, these concentrations of chlorine dioxide had similar effects on bacteria as 3 ppm of Kamoran® (recommended dosage for fermentation tanks), exception for B. subtilis, which could not be controlled at this Kamoran® dosage. The growth of industrial yeasts was affected when the concentration of chlorine dioxide was higher than 50 ppm, but the effect was slightly dependent on the type of yeast strain. Smooth yeast colonies (dispersed cells) seemed to be more sensitive than wrinkled yeast colonies (clustered cells/pseudohyphal growth), both isolated from an alcohol-producing unit during the 2006/2007 sugar cane harvest. The main advantage in the usage of chlorine dioxide that it can replace antibiotics, avoiding the selection of resistant populations of microorganisms.

Degradation of Phytate by High-PhytaseSaccharomyces cerevisiaeStrains during Simulated Gastrointestinal Digestion

Hydrolysis of extracellular phytate (InsP(6)) by high-phytase yeast strains and survival of yeast cells were studied at simulated digestive conditions using yeast peptone dextrose growth medium and wheat gruel as model meals. An in vitro digestion method was modified to better correlate with the gastric pH gradient following food intake in vivo. High-phytase yeast gave a strong reduction of InsP(6) (up to 60%) in the early gastric phase, as compared to no degradation by wild-type strains. The degree of InsP(6) degradation during digestion was influenced by the type of yeast strain, cell density, and InsP(6) concentration. Despite high InsP(6) solubility, high resistance against proteolysis by pepsin, and high cell survival, degradation in the late gastric and early intestinal phases was insignificant. Dependency on pH for phytase expression and/or activity seemed thus to be an important limiting factor. Although further studies are needed, our results show the potential of using yeast as a phytase carrier in the gastrointestinal tract.

Comparison of melibiose utilizing baker's yeast strains produced by genetic engineering and classical breeding.

Yeast strains currently used in the baking industry cannot fully utilize the trisaccharide raffinose found in beet molasses due to the absence of melibiase (alpha-galactosidase) activity. To overcome this deficiency, the MEL1 gene encoding melibiase enzyme was introduced into baker's yeast by both classical breeding and recombinant DNA technology. Both types of yeast strains were capable of vigorous fermentation in the presence of high levels of sucrose, making them suitable for the rapidly developing Asian markets where high levels of sugar are used in bread manufacture. Melibiase expression appeared to be dosage-dependent, with relatively low expression sufficient for complete melibiose utilization in a model fermentation system.

Fermentation parameters influencing higher alcohol production in the tequila process

In the fermentation process of tequila, the type of yeast strain, the temperature (30 or 35°C) and the C/N ratio (62 or 188) had a significant influence in the level of higher alcohols produced. On the contrary, other parameters like nitrogen source [urea or (NH)SO] and inoculum amount (5% or 10%), have little or no influence on the production of the compounds responsible for some of the organoleptic properties of tequila.