ORCID Profile
0000-0002-7997-6131
Current Organisations
Evotec (United Kingdom)
,
University of Adelaide
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Research Topics
In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Top 5 Research Topics
ANZSRC Field of Research (FoR)
Horticultural Production | Fermentation, Biotechnology And Industrial Microbiology | Wine Chemistry and Wine Sensory Science | Plant Physiology | Industrial Biotechnology | Analytical Biochemistry | Oenology and Viticulture | Plant Pathology | Food Processing | Genetic Technologies: Transformation, Site-Directed Mutagenesis, Etc. | Oenology And Viticulture | Plant Protection (Pests, Diseases And Weeds) | Food Sciences |
ANZSRC Socio-Economic Objective (SEO)
Beverages (e.g. alcohol, wines, soft drinks, excl. fruit juices) | Vegetables | Grapes | Horticultural crops | Wine Grapes | Beverages (excl. Fruit Juices) | Expanding Knowledge in the Agricultural and Veterinary Sciences | Processed food products and beverages
Related Links
Publications
Characterization of EstCOo8 and EstC34, intracellular esterases, from the wine-associated lactic acid bacteria Oenococcus oeni and Lactobacillus hilgardii
Publisher: Oxford University Press (OUP)
Date: 20-12-2013
DOI: 10.1111/JAM.12060
Abstract: To clone and characterize two related intracellular esterases from Oenococcus oeni and Lactobacillus hilgardii under wine-like conditions. The published genome sequences for O. oeni and Lact. hilgardii were used to identify, clone and purify putative esterase genes from these species designated EstCOo8 and EstC34, respectively. Both esterases are members of family V of lipolytic enzymes. However, EstC34 contains an SGSLG nucleophilic elbow structural motif instead of the usual GGSLG motif which is conserved in other lactic acid bacteria. Both esterases exhibited greatest specificity for C(2) -C(4) pNP-linked substrates and retained activity under wine-like conditions. EstCOo8 had an optimum temperature, pH, and ethanol concentration of 40°C, 5.5 and 6% (v/v), respectively. Whereas EstC34 had an optimum temperature, pH and ethanol concentration of 50°C, 5.0 and 10% (v/v), respectively. Both esterases were stable and retained activity under conditions that would be encountered in wine. They have the potential to reduce short-chain ethyl esters such as ethyl acetate. This study provides information that might help improve the performance of LAB during malolactic fermentation in wine in the future, either by strain selection, optimization or direct enzyme addition.
Relative Efficacy of High-Pressure Hot Water and High-Power Ultrasonics for Wine Oak Barrel Sanitization
Publisher: American Society for Enology and Viticulture
Date: 31-08-2011
Aroma Potential of Oak Battens Prepared from Decommissioned Oak Barrels
Publisher: American Chemical Society (ACS)
Date: 27-03-2015
Abstract: 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. This study investigated whether or not decommissioned barrels can be "reclaimed" and utilized as a previously untapped source of quality oak for wine maturation. Oak battens were prepared from staves of decommissioned French and American oak barrels, and their composition analyzed before and after toasting. The oak lactone glycoconjugate content of untoasted reclaimed oak was determined by liquid chromatography-tandem mass spectrometry, while the concentrations of cis- and trans-oak lactone, guaiacol, 4-methlyguaiacol, vanillin, eugenol, furfural, and 5-methylfurfural present in toasted reclaimed oak were determined by gas chromatography-mass spectrometry. Aroma potential was then evaluated by comparing the composition of reclaimed oak with that of new oak. Comparable levels of oak lactone glycoconjugates and oak volatiles were observed, demonstrating the aroma potential of reclaimed oak and therefore its suitability as a raw material for alternative oak products, i.e., chips or battens, for the maturation of wine. The temperature profiles achieved during toasting were also measured to evaluate the viability of any yeast or bacteria present in reclaimed oak.
Managing the excessive proliferation of glycogen accumulating organisms in industrial activated sludge by nitrogen supplementation
Publisher: Elsevier BV
Date: 12-2017
Implications of new research and technologies for malolactic fermentation in wine
Publisher: Springer Science and Business Media LLC
Date: 21-08-2014
DOI: 10.1007/S00253-014-5976-0
Abstract: 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. The ability to metabolise L-malic acid is strain specific, and both in idual Oenococcus oeni strains and other LAB strains vary in their ability to efficiently carry out MLF. Aside from impacts on acidity, LAB can also metabolise other precursors present in wine during fermentation and, therefore, alter the chemical composition of the wine resulting in an increased complexity of wine aroma and flavour. Recent research has focused on three main areas: enzymatic changes during MLF, safety of the final product and mechanisms of stress resistance. This review summarises the latest research and technological advances in the rapidly evolving study of MLF and investigates the directions that future research may take.
Isolation and Characterization of High-Ethanol-Tolerance Lactic Acid Bacteria from Australian Wine
Publisher: MDPI AG
Date: 25-04-2022
Abstract: Lactic acid bacteria are very important in winemaking. In this study, 108 lactic acid bacteria isolates were obtained from high-ethanol-content (~17% (v/v)) Grenache wines during uninoculated malolactic fermentation (MLF). The 16S rRNA and species-specific PCR showed that 104 of these were Oenococcusoeni, three were Lactobacillus hilgardii, and one was Staphylococcus pasteuri. AFLP of HindIII and MseI digests of the genomic DNA of the O. oeni strains was developed for the first time to discriminate the strains. The results showed that the method was a suitable technique for discriminating the O. oeni strains. Based on the cluster analysis, nine O. oeni strains were chosen for inclusion in an ethanol tolerance assay involving monitoring of optical density (ABS600nm) and viable plating. Several O. oeni strains (G63, G46, G71, G39) survived and grew well in MRS-AJ with 17% (v/v) ethanol, while the commercial O. oeni reference strain did not. Strain G63 could also survive and grow for 168 h after inoculation in MRS-AJ medium with 19% (v/v) ethanol. These results suggest that O. oeni G63, G46, G71, and G39 could potentially be used as MLF starters for high-ethanol-content wines. All three L. hilgardii strains could survive and grow in MRS-AJ with 19% (v/v) ethanol, perhaps also indicating their suitability as next-generation MLF starter cultures.
Cloning and characterization of an intracellular esterase from the wine-associated lactic acid bacterium Oenococcus oeni
Publisher: American Society for Microbiology
Date: 11-2009
DOI: 10.1128/AEM.01563-09
Abstract: We report the cloning and characterization of EstB28, the first esterase to be so characterized from the wine-associated lactic acid bacterium, Oenococcus oeni . The published sequence for O. oeni strain PSU-1 was used to identify putative esterase genes and design PCR primers in order to lify the corresponding region from strain Ooeni28, an isolate intended for inoculation of wines. In this way a 912-bp open reading frame (ORF) encoding a putative esterase of 34.5 kDa was obtained. The amino acid sequence indicated that EstB28 is a member of family IV of lipolytic enzymes and contains the GDSAG motif common to other lactic acid bacteria. This ORF was cloned into Escherichia coli using an appropriate expression system, and the recombinant esterase was purified. Characterization of EstB28 revealed that the optimum temperature, pH, and ethanol concentration were 40°C, pH 5.0, and 28% (vol/vol), respectively. EstB28 also retained marked activity under conditions relevant to winemaking (10 to 20°C, pH 3.5, 14% [vol/vol] ethanol). Kinetic constants were determined for EstB28 with p -nitrophenyl ( p NP)-linked substrates ranging in chain length from C 2 to C 18 . EstB28 exhibited greatest specificity for C 2 to C 4 p NP-linked substrates.
Nanoscale Properties of Human Telomeres Measured with a Dual Purpose X-ray Fluorescence and Super Resolution Microscopy Gold Nanoparticle Probe
Publisher: American Chemical Society (ACS)
Date: 11-2017
The Chemistry and Biology of Winemaking. By Ian Hornsey.
Publisher: Wiley
Date: 12-12-2007
Characterization and amino acid metabolism performances of indigenous Oenococcus oeni isolated from Chinese wines
Publisher: Springer Science and Business Media LLC
Date: 09-11-2013
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
Publisher: Springer Science and Business Media LLC
Date: 29-09-2012
DOI: 10.1007/S00253-012-4409-1
Abstract: 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. The identification and evaluation of a panel of nine reference genes, including the commonly used ldhD, for real-time PCR normalisation was performed in O. oeni. Expression levels of these reference genes were then measured by real-time qPCR in an independent set of O. oeni s les (n = 30). The nine genes were ranked according to their stability of gene expression measure (M) using geNorm to identify the most consistently expressed reference genes. This approach resulted in the identification of multiple reference genes that may be used for a screening and more robust normalisation of target gene expression measured by real-time RT-qPCR. Expression of esterase genes was then measured in these O. oeni s les in the presence of known esterase substrates. The results give an indication of how these genes may be involved in ester synthesis and hydrolysis in O. oeni.
Biochemical characterisation of the esterase activities of wine lactic acid bacteria
Publisher: Springer Science and Business Media LLC
Date: 09-09-2007
DOI: 10.1007/S00253-007-1173-8
Abstract: Esters are an important group of volatile compounds that can contribute to wine flavour. Wine lactic acid bacteria (LAB) have been shown to produce esterases capable of hydrolysing ester substrates. This study aims to characterise the esterase activities of nine LAB strains under important wine conditions, namely, acidic conditions, low temperature (to 10 degrees C) and in the presence of ethanol (2-18% v/v). Esterase substrate specificity was also examined using seven different ester substrates. The bacteria were generally found to have a broad pH activity range, with the majority of strains showing maximum activity close to pH 6.0. Exceptions included an Oenococcus oeni strain that retained most activity even down to a pH of 4.0. Most strains exhibited highest activity across the range 30-40 degrees C. Increasing ethanol concentration stimulated activity in some of the strains. In particular, O. oeni showed an increase in activity up to a maximum ethanol concentration of around 16%. Generally, strains were found to have greater activity towards short-chained esters (C2-C8) compared to long-chained esters (C10-C18). Even though the optimal physicochemical conditions for enzyme activity differed from those found in wine, these findings are of potential importance to oenology because significant activities remained under wine-like conditions.
Improving Oenococcus oeni to overcome challenges of wine malolactic fermentation
Publisher: Elsevier BV
Date: 09-2015
DOI: 10.1016/J.TIBTECH.2015.06.008
Abstract: Oenococcus oeni is crucial for winemaking, bringing stabilization, deacidification, and sensory impacts through malolactic fermentation (MLF) to most wine styles. The poor nutritional make-up of wine together with typically low processing temperatures and pH and high ethanol content and sulfur dioxide (SO2) hinder O. oeni growth and activity. Production delays and interventions with starter cultures and nutritional supplements have significant cost and quality implications thus, optimization of O. oeni has long been a priority. A range of optimization strategies, some guided by detailed characterization of O. oeni, have been exploited. Varying degrees of success have been seen with classical strain selection, mutagenesis, gene recombination, genome shuffling, and, most recently, directed evolution (DE). The merits, limitations, and future prospects of each are discussed.
Viability of common wine spoilage organisms after exposure to high power ultrasonics
Publisher: Elsevier BV
Date: 05-2012
DOI: 10.1016/J.ULTSONCH.2011.06.009
Abstract: 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. Several wine spoilage yeasts and bacteria were treated with HPU in saline (0.9% w/v NaCl), juice and red wine to assess their susceptibility to HPU. Significant killing was seen across several yeasts and bacteria commonly associated with winemaking and wine spoilage. In general the viability of yeast was more affected than that of bacteria.
High power ultrasonics as a novel tool offering new opportunities for managing wine microbiology
Publisher: Springer Science and Business Media LLC
Date: 06-09-2007
DOI: 10.1007/S10529-007-9518-Z
Abstract: Industrial scale food and beverage processes that utilize microorganisms are typically faced with issues related to the exclusion, suppression or elimination of spoilage organisms. Yet the use of traditional anti-microbial treatments such as heat, chemical biocides or sterile filtration may themselves be restricted by regulations or else be undesirable due to their adverse sensory impacts on the product. High power ultrasound (HPU) is a technology whose application has been evaluated if not exploited in several food and beverage processes but has yet to be introduced into the wine industry. This review examines the research findings from related industries and highlights possible applications and likely benefits of the use of HPU in winemaking.
Dekkera and Brettanomyces growth and utilisation of hydroxycinnamic acids in synthetic media
Publisher: Springer Science and Business Media LLC
Date: 04-2008
DOI: 10.1007/S00253-007-1328-7
Abstract: Dekkera and Brettanomyces yeast are important spoilage organisms in a number of food and beverage products. Isolates of both genera were cultured in a defined medium and supplemented with hydroxycinnamic acids and vinylphenols to investigate their influence on growth and the formation of ethyl phenol derivatives. The growth rate of Brettanomyces species in the presence of acids was reduced, and no significant conversion to vinyl or ethyl derivatives was observed. The growth rate and substrate utilisation rates of Dekkera anomala and Dekkera bruxellensis yeast differed depending on strain and the acid precursor present. Growth of D. bruxellensis was slowed by the presence of ferulic acid with the addition of 1 mM ferulic acid completely inhibiting growth. This study provides an insight into the spoilage potential of these organisms and possible control strategies involving hydroxycinnamic acids.
Mousy off-flavour production in grape juice and wine by Dekkera and Brettanomyces yeasts
Publisher: Hindawi Limited
Date: 10-2000
Survey of enzyme activity responsible for phenolic off-flavour production by Dekkera and Brettanomyces yeast
Publisher: Springer Science and Business Media LLC
Date: 2009
DOI: 10.1007/S00253-008-1708-7
Abstract: Volatile phenols are produced by Dekkera yeasts and are of organoleptic importance in alcoholic beverages. The key compound in this respect is 4-ethylphenol, responsible for the medicinal and phenolic aromas in spoiled wines. The microbial synthesis of volatile phenols is thought to occur in two steps, beginning with naturally occurring hydroxycinnamic acids (HCAs). The enzyme phenolic acid decarboxylase (PAD) converts HCAs to vinyl derivatives, which are the substrates of a second enzyme, postulated to be a vinylphenol reductase (VPR), whose activity results in the formation of ethylphenols. Here, both steps of the pathway are investigated, using cell extracts from a number of Dekkera and Brettanomyces species. Dekkera species catabolise ferulic, caffeic and p-coumaric acids and possess inducible enzymes with similar pH and temperature optima. Brettanomyces does not decarboxylate HCAs but does metabolise vinylphenols. Dekkera species form ethylphenols but the VPR enzyme appears to be highly unstable in cell extracts. A partial protein sequence for PAD was determined from Dekkera anomala and may indicate the presence of a novel enzyme in this genus.
Occurrence of 2-Acetyl-1-Pyrroline in Mousy Wines
Publisher: Informa UK Limited
Date: 09-1995
Oenological traits of Lachancea thermotolerans show signs of domestication and allopatric differentiation
Publisher: Springer Science and Business Media LLC
Date: 04-10-2018
DOI: 10.1038/S41598-018-33105-7
Abstract: 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 erse ecological niches worldwide, classified in nine genetic groups based on their pre-determined microsatellite genotypes. The strains and the genetic groups were compared for their alcoholic fermentation performance, production of primary and secondary metabolites and pH modulation in Chardonnay grape juice fermentations. The common oenological features of L. thermotolerans strains were their glucophilic character, relatively extensive fermentation ability, low production of acetic acid and the formation of lactic acid, which significantly affected the pH of the wines. An untargeted analysis of volatile compounds, used for the first time in a population-scale phenotyping of a non- Saccharomyces yeast, revealed that 58 out of 90 volatiles were affected at an L. thermotolerans strain level. Besides the remarkable extent of intra-specific ersity, our results confirmed the distinct phenotypic performance of L. thermotolerans genetic groups. Together, these observations provide further support for the occurrence of domestication events and allopatric differentiation in L. thermotolerans population.
The pentose phosphate pathway in the yeasts Saccharomyces cerevisiae and Kloeckera apiculata, an exercise in comparative metabolism for food and wine science students
Publisher: Wiley
Date: 11-2001
Competition experiments between Brettanomyces bruxellensis strains reveal specific adaptation to sulfur dioxide and complex interactions at intraspecies level
Publisher: Oxford University Press (OUP)
Date: 05-02-2019
Abstract: Recent studies have suggested a strong niche adaptation for Brettanomyces bruxellensis strains according to human-related fermentation environments, including beer, wine and bioethanol. This is further supported by a correlation between B. bruxellensis genetic grouping and tolerance to SO2, the main antimicrobial used in wine. The allotriploid AWRI1499-like cluster, in particular, shows high SO2 tolerance suggesting that the genetic configuration observed for these strains may confer a selective advantage in winemaking conditions. To test this hypothesis, we evaluated the relative selective advantage of representatives of the three main B. bruxellensis genetic groups in presence of SO2. As a proof-of-concept and using recently developed transformation cassettes, we compared strains under different SO2 concentrations using pairwise competitive fitness experiments. Our results showed that AWRI1499 is specifically adapted to environments with high SO2 concentrations compared to other B. bruxellensis wine strains, indicating a potential correlation between allotriploidisation origin and environmental adaptation in this species. Additionally, our findings suggest different types of competition between strains, such as coexistence and exclusion, revealing new insights on B. bruxellensis interactions at intraspecies level.
Impact of Australian Dekkera bruxellensis strains grown under oxygen-limited conditions on model wine composition and aroma
Publisher: Elsevier BV
Date: 12-2013
Abstract: 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. bruxellensis growth in wine. We demonstrate that whereas the presence of oxygen accelerates the growth of this species, oxygen-limited conditions favour 4-ethylphenol production. Consequently, we evaluated wine spoilage potential of three D. bruxellensis strains (AWRI1499, AWRI1608 and AWRI1613) under oxygen-limited conditions. Each strain was cultured in a chemically-defined wine medium and the fermentation products were analysed using HPLC and HS-SPME-GC/MS. The strains displayed different growth characteristics but were equally capable of producing ethylphenols. On the other hand, significant differences were observed for 18 of the remaining 33 metabolites analysed and duo-trio sensory analysis indicated significant aroma differences between wines inoculated with AWRI1499 and AWRI1613. When these wines were spiked with low concentrations of 4-ethylphenol and 4-ethylguaiacol, no sensorial differences could be perceived. Together these data suggest that the three predominant D. bruxellensis strains previously isolated during a large survey of Australian wineries do not differ substantively in their capacity to grow in, and spoil, a model wine medium.
Factors affecting extraction and evolution of phenolic compounds during red wine maceration and the role of process modelling
Publisher: Elsevier BV
Date: 11-2017
Brettanomyces bruxellensis population survey reveals a diploid-triploid complex structured according to substrate of isolation and geographical distribution
Publisher: Springer Science and Business Media LLC
Date: 07-03-2018
DOI: 10.1038/S41598-018-22580-7
Abstract: Brettanomyces bruxellensis is a unicellular fungus of increasing industrial and scientific interest over the past 15 years. Previous studies revealed high genotypic ersity amongst B. bruxellensis strains as well as strain-dependent phenotypic characteristics. Genomic assemblies revealed that some strains harbour triploid genomes and based upon prior genotyping it was inferred that a triploid population was widely dispersed across Australian wine regions. We performed an intraspecific ersity genotypic survey of 1488 B. bruxellensis isolates from 29 countries, 5 continents and 9 different fermentation niches. Using microsatellite analysis in combination with different statistical approaches, we demonstrate that the studied population is structured according to ploidy level, substrate of isolation and geographical origin of the strains, underlying the relative importance of each factor. We found that geographical origin has a different contribution to the population structure according to the substrate of origin, suggesting an anthropic influence on the spatial bio ersity of this microorganism of industrial interest. The observed clustering was correlated to variable stress response, as strains from different groups displayed variation in tolerance to the wine preservative sulfur dioxide (SO 2 ). The potential contribution of the triploid state for adaptation to industrial fermentations and dissemination of the species B. bruxellensis is discussed.
The Role of Lysine Amino Nitrogen in the Biosynthesis of Mousy Off-Flavor Compounds byDekkera anomala
Publisher: American Chemical Society (ACS)
Date: 27-11-2007
DOI: 10.1021/JF071243E
Abstract: Mousy off-flavor is an insidious and economically disastrous microbiologically derived spoilage characteristic of wine and other fermented beverages. Tainted wines are rendered unpalatable and there is currently no satisfactory procedure for removal of the off-flavor. Here we report the confirmation of that both d- and l-lysine can act as a precursor for the formation of mousy off-flavor N-heterocycles. Further, through the use of stable isotope feeding experiments, we could establish that a pentylamine group from lysine is incorporated into the piperideine moiety of two off-flavor N-heterocycles. A biochemical pathway for the formation of mousy off-flavor compounds is proposed.
Impact of Lachancea thermotolerans on Chemical Composition and Sensory Profiles of Viognier Wines
Publisher: MDPI AG
Date: 30-04-2022
DOI: 10.3390/JOF8050474
Abstract: Viognier is a warm climate grape variety prone to loss of acidity and accumulation of excessive sugars. The yeast Lachancea thermotolerans 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 L. thermotolerans strains in co-inoculations and sequential inoculations with Saccharomyces cerevisiae in high sugar H Viognier fermentations. The results highlighted the dichotomy between the non-acidified and the bio-acidified L. thermotolerans treatments, with either comparable or up to 0.5 units lower pH relative to the S. cerevisiae control. Significant differences were detected in a range of flavour-active yeast volatile metabolites. The perceived acidity mirrored the modulations in wine pH/TA, as confirmed via “Rate-All-That-Apply” sensory analysis. Despite major variations in the volatile composition and acidity alike, the varietal aromatic expression (i.e., stone fruit aroma/flavour) remained conserved between the treatments.
Modelling the Mass Transfer Process of Malvidin-3-Glucoside during Simulated Extraction from Fresh Grape Solids under Wine-Like Conditions
Publisher: MDPI AG
Date: 27-08-2018
DOI: 10.3390/MOLECULES23092159
Abstract: 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. Factor levels were chosen to simulate conditions found at various points during the maceration and fermentation steps of the red winemaking process. A rigorous mathematical model was developed and applied to experimental extraction curves, allowing the separation of mass transport properties in liquid and solid phases in a wine-like system, for the first time. In all cases, the coefficient of determination exceeded 0.92, indicating good agreement between experimental and mathematically-solved M3G concentrations. For the conditions studied, internal mass transfer was found to limit M3G extraction and changes to the liquid phase composition and temperature influence the distribution constant. Surface response models of mass transfer parameters were developed to allow future simulations of fermentation scenarios aimed at maximising the extraction potential of M3G.
Inhibitory effect of hydroxycinnamic acids on Dekkera spp.
Publisher: Springer Science and Business Media LLC
Date: 02-12-2009
DOI: 10.1007/S00253-009-2352-6
Abstract: 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. In the presence of ethanol, the inhibitory effects of ferulic acid were lified. Scanning electron microscopy images reveal cellular damage upon exposure to ferulic acid. Thus, manipulation of ferulic acid concentrations could be of industrial significance for control of Dekkera and may be the basis for differences in susceptibility of wines to Dekkera spoilage.
A survey of lactic acid bacteria for enzymes of interest to oenology
Publisher: Hindawi Limited
Date: 10-2006
Mass Transfer of Anthocyanins during Extraction from Pre-Fermentative Grape Solids under Simulated Fermentation Conditions: Effect of Convective Conditions
Publisher: MDPI AG
Date: 26-12-2018
DOI: 10.3390/MOLECULES24010073
Abstract: 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. A mathematical model that separates solid and liquid phase mass transfer parameters was applied to experimental extraction curves, and in all cases, provided a coefficient of determination exceeding 0.97. Calculated mass transfer coefficients indicated that under forced convective conditions, the extraction process was controlled by internal diffusion whereas under natural convection, both internal diffusion and liquid-phase mass transfer were relevant in determining the overall extraction rate. Predictive simulations of M3G extraction during active fermentation were accomplished by incorporating the current results with a previously developed fermentation model, providing insight into the effect of a dynamic liquid phase on anthocyanin extraction.
Microbial modulation of aromatic esters in wine: Current knowledge and future prospects
Publisher: Elsevier BV
Date: 07-2010
Remediation of Thiothrix spp. associated bulking problems by raw wastewater feeding: A full-scale experience
Publisher: Elsevier BV
Date: 09-2017
DOI: 10.1016/J.SYAPM.2017.06.004
Abstract: 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. Chemical analysis of the raw influent showed it was composed of a mixture of organic acids, phenols and alcohols. The CAL effluent was characterised by high acetic acid and phenolic concentrations. An attempt was made to manipulate the SBR microbial community to improve settling by direct feeding small volumes of raw influent into the SBR. After raw feeding, the plant ceased bulking as the settled sludge volume reduced from 930 to 200mLL
Directed evolution of Oenococcus oeni strains for more efficient malolactic fermentation in a multi-stressor wine environment
Publisher: Elsevier BV
Date: 08-2018
Abstract: 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. oeni strain, A90. The strain was grown for ∼350 generations in a red wine-like environment with increasing levels of stressors. Three strains were selected from screening experiments based on their completion of fermentation in a synthetic wine/wine blend with 15.1% (v/v) ethanol, 26 mg/L SO
Ester synthesis and hydrolysis in an aqueous environment, and strain specific changes during malolactic fermentation in wine with Oenococcus oeni
Publisher: Elsevier BV
Date: 12-2013
DOI: 10.1016/J.FOODCHEM.2013.03.087
Abstract: 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. Two purified esterases (EstA2 and EstB28) synthesised ethyl butanoate and ethyl hexanoate to varying degrees. Both purified esterases hydrolysed ethyl butanoate, ethyl hexanoate and ethyl octanoate. Once this dual activity was confirmed, malolactic fermentation (MLF) trials were conducted in wine with O. oeni strains that had been previously observed to have either high or low esterase activity against artificial substrates. Strain specific differences were observed and strains with low esterase hydrolysis activity against artificial substrates had a higher level of total esters measured after MLF. The results demonstrate the impact that O. oeni has on wine aroma and relates this to the ester hydrolysis and synthesis abilities of O. oeni strains.
Mousy Off-Flavor: A Review
Publisher: American Chemical Society (ACS)
Date: 08-08-2006
DOI: 10.1021/JF0528613
Abstract: Although mousy off-flavor occurs infrequently in wine, it can be economically disastrous to the wine producer as, at worst, it can render the wine unpalatable or, at best, decrease the quality of the wine resulting in a lower sale price. Wines infected with either lactic acid bacteria (LAB) (particularly heterofermentative strains) or Dekkera/Brettanomyces yeast can potentially produce mousy off-flavor. There are three known compounds that cause mousy off-flavor: 2-ethyltetrahydropyridine, 2-acetyltetrahydopyridine, and 2-acetylpyrroline. Dekkera/Brettanomyces have been shown to be capable of producing at least two of these compounds, whereas LAB are capable of producing all three. The reason as to why mousy off-flavor forms in some wines and not in others is still not fully understood. The issue is further complicated by the fact that the compounds that have thus far been identified as necessary for off-flavor formation are all potentially available in wine (e.g., ethanol, L-lysine, L-ornithine, and metal ions). For these reasons, the microbe's metabolism probably plays a key role in mousy off-flavor formation. In the case of Dekkera/Brettanomyces-induced mousy off-flavor, it appears that oxygen may play a key role. Thus, a wine infected with Dekkera/Brettanomyces in the absence of oxygen may not become mousy unless exposed to oxygen via a processing or handling procedure.
Lactic Acid Bacteria as a Potential Source of Enzymes for Use in Vinification
Publisher: American Society for Microbiology
Date: 10-2004
Genomic insights into the metabolism of ‘Candidatus Defluviicoccus seviourii’, a member of Defluviicoccus cluster III abundant in industrial activated sludge
Publisher: Oxford University Press (OUP)
Date: 26-11-2019
Abstract: 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. In this study, a near complete genome of an abundant filamentous DF3 named 'Candidatus Defluviicoccus seviourii' was obtained from a full-scale sequencing batch reactor (SBR) treating winery wastewater. Annotation of the 'Ca. D. seviourii' genome revealed interesting metabolic features that help to understand the abundance of this microorganism in industrial wastewater treatment plants. Their potential for the storage of polyhydroxyalkanoates (PHA) is suggested to favour these organisms with the intermittent availability of carbon in these systems. An ability to fix nitrogen and take up urea may provide them with an additional advantage with the characteristically high carbon to nitrogen content of industrial waste. The genome and preliminary findings of this study provide a foundation for further research into these biotechnologically relevant organisms.
Related Organisations
Evotec (United Kingdom)
Location: United Kingdom of Great Britain and Northern Ireland
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