Impact of on Chemical Composition and Sensory Profiles of Viognier Wines.

Viognier is a warm climate grape variety prone to loss of acidity and accumulation of excessive sugars. The yeast can improve the stability and balance of such wines due to the partial conversion of sugars to lactic acid during alcoholic fermentation. This study compared the performance of five strains in co-inoculations and sequential inoculations with in high sugar/pH Viognier fermentations.

Isolation and Characterization of High-Ethanol-Tolerance Lactic Acid Bacteria from Australian Wine.

Lactic acid bacteria are very important in winemaking. In this study, 108 lactic acid bacteria isolates were obtained from high-ethanol-content (~17% (/)) Grenache wines during uninoculated malolactic fermentation (MLF). The 16S rRNA and species-specific PCR showed that 104 of these were , three were , and one was .

Impact of Lachancea thermotolerans on chemical composition and sensory profiles of Merlot wines.

Wines from warm(ing) climates often contain excessive ethanol but lack acidity. The yeast Lachancea thermotolerans can ameliorate such wines due to partial conversion of sugars to lactic acid during alcoholic fermentation. This study compared the performance of five L.

Lower-alcohol wines produced by Metschnikowia pulcherrima and Saccharomyces cerevisiae co-fermentations: The effect of sequential inoculation timing.

In Latin, 'pulcherrima' is a superlative form of an adjective that translates as beautiful. Apart from being 'the most beautiful' yeast, Metschnikowia pulcherrima has a remarkable potential in production of wines with lower ethanol content. The oenological performance of six M.

Evaluation of indigenous non-Saccharomyces yeasts isolated from a South Australian vineyard for their potential as wine starter cultures.

The use of non-Saccharomyces yeast in conjunction with Saccharomyces cerevisiae in wine fermentation is a growing trend in the wine industry. Non-Saccharomyces, through their distinctive production of secondary metabolites, have the potential to positively contribute to wine sensory profile. To discover new candidate strains for development as starter cultures, indigenous non-Saccharomyces were isolated from un-inoculated fermenting Shiraz musts from a South Australian vineyard (McLaren Vale wine region) and characterised.

Mathematical modelling of anthocyanin mass transfer to predict extraction in simulated red wine fermentation scenarios.

Anthocyanins are polyphenolic compounds present in grapes that are responsible for the initial colour of red wine and their incorporation into derived pigments leads to long term colour stability. The ability to predict the effect of process variables, either controlled by winemakers or that naturally change throughout fermentation, on the extraction of anthocyanins is vital to producing red wine of high quality. A 2 factorial experiment with additional points located at central factor conditions was used to determine the impact of temperature, sugar and ethanol concentrations on the mass transfer properties of anthocyanins from fresh Pinot noir grape solids.

Measures to improve wine malolactic fermentation.

This review focuses on the considerable amount of research that has been directed towards the improvement of efficiency and reliability of malolactic fermentation (MLF), which is important in winemaking. From this large body of work, it is clear that reliable MLF is essential for process efficiency and prevention of spoilage in the final product. Impediments to successful MLF in wine, the impact of grape and wine ecology and how this may affect MLF outcome are discussed.

Mass Transfer of Anthocyanins during Extraction from Pre-Fermentative Grape Solids under Simulated Fermentation Conditions: Effect of Convective Conditions.

The colour of red wine is largely determined by the concentration of anthocyanins that are extracted from grape skins during fermentation. Because colour is a key parameter in determining the overall quality of the finished product, understanding the effect of processing variables on anthocyanin extraction is critical for producing a red wine with the desired sensorial characteristics. In this study, the effect of convective conditions (natural and forced) on the mass transfer properties of malvidin-3-glucoside (M3G) from pre-fermentative grape solids was explored at various liquid phase conditions representing stages of fermentation.

Genomic insights into the metabolism of 'Candidatus Defluviicoccus seviourii', a member of Defluviicoccus cluster III abundant in industrial activated sludge.

Filamentous cluster III Defluviicoccus (DF3) are known to proliferate and cause bulking issues in industrial wastewater treatment plants. Members of the genus Defluviicoccus are also known to exhibit the glycogen accumulating organism (GAO) phenotype, which is suggested to be detrimental to enhanced biological phosphorus removal (EBPR). Despite the reported negative impact members of the DF3 have on activated sludge wastewater treatment systems, limited research has focused on understanding the physiological traits that allow them to compete in these environments.

Oenological traits of Lachancea thermotolerans show signs of domestication and allopatric differentiation.

The yeast Lachancea thermotolerans (previously Kluyveromyces thermotolerans) is a species of large, yet underexplored, oenological potential. This study delivers comprehensive oenological phenomes of 94 L. thermotolerans strains obtained from diverse ecological niches worldwide, classified in nine genetic groups based on their pre-determined microsatellite genotypes.

Modelling the Mass Transfer Process of Malvidin-3-Glucoside during Simulated Extraction from Fresh Grape Solids under Wine-Like Conditions.

Extraction of grape components is a key consideration for red winemaking. The impact of changing process variables on mass transfer properties of anthocyanins from fresh pre-fermentative red grape solids under forced convective conditions was explored using the dominant red grape anthocyanin, malvidin-3-glucoside (M3G) as a model solute. A two level full factorial design was implemented to investigate effects of temperature, sugar and ethanol on mass transfer properties.

Genomic and Analyses Reveal the spp. as Abundant Fermentative Glycogen Accumulating Organisms in Enhanced Biological Phosphorus Removal Systems.

Enhanced biological phosphorus removal (EBPR) involves the cycling of biomass through carbon-rich (feast) and carbon-deficient (famine) conditions, promoting the activity of polyphosphate accumulating organisms (PAOs). However, several alternate metabolic strategies, without polyphosphate storage, are possessed by other organisms, which can compete with the PAO for carbon at the potential expense of EBPR efficiency. The most studied are the glycogen accumulating organisms (GAOs), which utilize aerobically stored glycogen to energize anaerobic substrate uptake and storage.

Genome Sequence of Australian Indigenous Wine Yeast Torulaspora delbrueckii COFT1 Using Nanopore Sequencing.

Here, we report the first sequenced genome of an indigenous Australian wine isolate of using the Oxford Nanopore MinION and Illumina HiSeq sequencing platforms. The genome size is 9.4 Mb and contains 4,831 genes.

Directed evolution of Oenococcus oeni strains for more efficient malolactic fermentation in a multi-stressor wine environment.

High concentrations of ethanol, low pH, the presence of sulfur dioxide and some polyphenols have been reported to inhibit Oenococcus oeni growth, thereby negatively affecting malolactic fermentation (MLF) of wine. In order to generate superior O. oeni strains that can conduct more efficient MLF, despite these multiple stressors, a continuous culture approach was designed to directly evolve an existing ethanol tolerant O.

Disruption of the cell wall integrity gene ECM33 results in improved fermentation by wine yeast.

Severe oenological conditions, such as limited assimilable nitrogen and high sugar contents restrict yeast's ability to successfully complete fermentation. In the absence of a comprehensive commercially available deletion collection in a wine yeast background, a screening approach was applied to a transposon library in a wine yeast derivative to identify clones with superior fermentation performance. Five candidate genes, when disrupted by Ty insertion, were identified as enabling yeast to efficiently complete a model oenological fermentation with limited nitrogen availability.

Application of directed evolution to develop ethanol tolerant Oenococcus oeni for more efficient malolactic fermentation.

Malolactic fermentation (MLF) is an important step in winemaking, which can be notoriously unreliable due to the fastidious nature of Oenococcus oeni. This study aimed to use directed evolution (DE) to produce a more robust strain of O. oeni having the ability to withstand high ethanol concentrations.

Managing the excessive proliferation of glycogen accumulating organisms in industrial activated sludge by nitrogen supplementation: A FISH-NanoSIMS approach.

Defluviicoccus vanus-related glycogen accumulating organisms (GAO) regularly proliferate in industrial wastewater treatment plants handling high carbon but nitrogen deficient wastes. When GAO dominate, they are associated with poor performance, characterised by slow settling biomass and turbid effluents. Although their ecophysiology has been studied thoroughly in domestic waste treatment plants, little attention has been paid to them in aerobic industrial systems.

Remediation of Thiothrix spp. associated bulking problems by raw wastewater feeding: A full-scale experience.

An industrial wastewater treatment plant (WWTP) in Australia has long suffered from bulking problems associated with the proliferation of Thiothrix spp. The WWTP consists of a covered anaerobic lagoon (CAL) followed by a sequencing batch reactor (SBR). The CAL functions as both an anaerobic digester and surge lagoon for the irregular flow of wastewater generated from the production of seasonal products.

Aroma potential of oak battens prepared from decommissioned oak barrels.

During barrel maturation, volatile compounds are extracted from oak wood and impart aroma and flavor to wine, enhancing its character and complexity. However, barrels contain a finite pool of extractable material, which diminishes with time. As a consequence, most barrels are decommissioned after 5 or 6 years.

Implications of new research and technologies for malolactic fermentation in wine.

The initial conversion of grape must to wine is an alcoholic fermentation (AF) largely carried out by one or more strains of yeast, typically Saccharomyces cerevisiae. After the AF, a secondary or malolactic fermentation (MLF) which is carried out by lactic acid bacteria (LAB) is often undertaken. The MLF involves the bioconversion of malic acid to lactic acid and carbon dioxide.

Impact of Australian Dekkera bruxellensis strains grown under oxygen-limited conditions on model wine composition and aroma.

Spoilage of red wine by the yeast species Dekkera bruxellensis is a common problem for the global wine industry. When conditions are conducive for growth of these yeasts in wine, they efficiently convert non-volatile hydroxycinnamic acids into aroma-active ethylphenols, thereby reducing the quality of the wine. It has been demonstrated previously that dissolved oxygen is a key factor which stimulates D.

Ester synthesis and hydrolysis in an aqueous environment, and strain specific changes during malolactic fermentation in wine with Oenococcus oeni.

Previous work has shown that Oenococcus oeni produces esterases that are capable of hydrolysing artificial substrates. Using SPME-GCMS, this study provides evidence that purified O. oeni esterases have the ability to both synthesise and hydrolyse esters.

Validation of the use of multiple internal control genes, and the application of real-time quantitative PCR, to study esterase gene expression in Oenococcus oeni.

The study of gene expression and accurate quantitation of target genes in any organism depends on correct normalisation. Due to the increase in studies on Oenococcus oeni gene expression, there is a clear need for alternative reference genes in order to reliably measure expression levels. In this manuscript, we propose the approach of using multiple reference genes to provide a more robust basis for establishing a reference gene set.

Viability of common wine spoilage organisms after exposure to high power ultrasonics.

Microbial spoilage of wine can lead to significant economic loss. At present sulfur dioxide is the main additive to juice/must/wine to prevent and control microbial spoilage. As an alternative, or complement to SO(2), high power ultrasonics (HPU) may be used to control microbes.

Inhibitory effect of hydroxycinnamic acids on Dekkera spp.

Simple phenolic components of wine, hydroxycinnamic acids (HCAs) are known to have antimicrobial properties. This study sought to determine the potential of ferulic acid as an antifungal agent for the control of Dekkera. Growth was inhibited by all HCAs examined in this study, with ferulic acid being the most potent at all concentrations.