The Australian Wine Research Institute

Urrbrae, Australia

The Australian Wine Research Institute

Urrbrae, Australia
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Abrahamse C.E.,The Australian Wine Research Institute | Bartowsky E.J.,The Australian Wine Research Institute
World Journal of Microbiology and Biotechnology | Year: 2012

Malolactic fermentation (MLF) is an integral step in red winemaking, which in addition to deacidifying wine can also influence the composition of volatile fermentation-derived compounds with concomitant affects on wine sensory properties. Long-established winemaking protocols for MLF induction generally involve inoculation of bacteria starter cultures post alcoholic fermentation, however, more recently there has been a trend to introduce bacteria earlier in the fermentation process. For the first time, this study shows the impact of bacterial inoculation on wine quality parameters that define red wine, including wine colour and phenolics, and volatile fermentation-derived compounds. This study investigates the effects of inoculating Shiraz grape must with malolactic bacteria at various stages of alcoholic fermentation [beginning of alcoholic fermentation (co-inoculation, with yeast), mid-alcoholic fermentation, at pressing and post alcoholic fermentation] on the kinetics of MLF and wine chemical composition. Co-inoculation greatly reduced the overall fermentation time by up to 6 weeks, the rate of alcoholic fermentation was not affected by the presence of bacteria and the fermentation-derived wine volatiles profile was distinct from wines produced where bacteria were inoculated late or post alcoholic fermentation. An overall slight decrease in wine colour density observed following MLF was not influenced by the MLF inoculation regime. However, there were differences in anthocyanin and pigmented polymer composition, with co-inoculation exhibiting the most distinct profile. Differences in yeast and bacteria metabolism at various stages in fermentation are proposed as the drivers for differences in volatile chemical composition. This study demonstrates, with an in-depth analysis, that co-inoculation of yeast and bacteria in wine fermentation results in shorter total vinification time and produces sound wines, thus providing the opportunity to stabilise wines more rapidly than traditional inoculation regimes permit and thereby reducing potential for microbial spoilage. © 2011 Springer Science+Business Media B.V.

Cozzolino D.,The Australian Wine Research Institute | Curtin C.,The Australian Wine Research Institute
Food Control | Year: 2012

Effective fermentation monitoring is a growing need during the production of wine due to the rapid pace of change in the industry, which calls for fast methods providing real-time information in order to reduce stuck and sluggish fermentations and to assure the quality of the product at all stages of the process. During wine fermentation it is important to measure both substrate and product concentrations (e.g. sugars, ethanol) and to evaluate other quality characteristics of the final product, such as the phenolic composition or volatile compounds. However, the analysis of these compounds by traditional methods requires sample preparation, specific analytical equipment and is time-consuming. Therefore real-time monitoring and control of the bioprocesses are necessary for increased productivity, efficiency, and reproducibility. The aim of this study is to evaluate the potential of attenuated total reflectance (ATR) mid infrared (MIR) spectroscopy to monitor wild ferments during wine production. The results obtained showed that it is possible to monitor the time course of fermentation in wild yeast using ATR-MIR spectroscopy. Partial least squares (PLS) regression models allowed to predict the time course of fermentation (standard error of prediction 1.2 days). © 2012 Elsevier Ltd.

This paper describes the development and application of a novel method for the analysis of phthalates in wine using HPLC-MS/MS combined with a hold-back column. Phthalates are ubiquitous contaminants in the environment and can be widely found in laboratory materials and equipment. A HPLC system is no exception and can be the source of contamination affecting the accuracy and precision of analytical results. The new method successfully separates phthalates from the different sources, a wine sample and HPLC system by a simple technique using an additional HPLC column (a hold-back column) placed upstream of the injection valve. The hold-back column effectively retains the HPLC-derived contaminants during column equilibrium time and delays their elution times from an analytical column. Consequently, a phthalate from a wine sample can be baseline separated as it elutes sufficiently earlier than the same phthalate from the HPLC system. HPLC-MS/MS analysis combined with the hold-back column demonstrated virtually no influence of the HPLC contaminants on the quantification of phthalates present in wine. Together with a simple and rapid sample preparation and the use of labeled internal standards, the method was confirmed to be robust and reliable to determine concentrations of phthalates in wine. Quantification limits were within the range of 1.6-9.8 μg L-1 for dimethyl, diethyl, dibutyl, benzylbutyl, bis(2-ethylhexyl) and dioctyl phthalates, and 7.5-26.6 μgL-1 for multiple isomeric phthalates, di-iso-nonyl and di-iso-dodecyl phthalates. © 2014 Elsevier B.V.

Borneman A.R.,The Australian Wine Research Institute | Pretorius I.S.,Macquarie University
Genetics | Year: 2015

The Saccharomyces sensu stricto group encompasses species ranging from the industrially ubiquitous yeast Saccharomyces cerevisiae to those that are confined to geographically limited environmental niches. The wealth of genomic data that are now available for the Saccharomyces genus is providing unprecedented insights into the genomic processes that can drive speciation and evolution, both in the natural environment and in response to human-driven selective forces during the historical “domestication” of these yeasts for baking, brewing, and winemaking. © 2015, by the Genetics Society of America. All rights reserved.

Curtin C.D.,The Australian Wine Research Institute | Pretorius I.S.,Macquarie University
FEMS Yeast Research | Year: 2014

Brettanomyces bruxellensis, like its wine yeast counterpart Saccharomyces cerevisiae, is intrinsically linked with industrial fermentations. In wine, B. bruxellensis is generally considered to contribute negative influences on wine quality, whereas for some styles of beer, it is an essential contributor. More recently, it has shown some potential for bioethanol production. Our relatively poor understanding of B. bruxellensis biology, at least when compared with S. cerevisiae, is partly due to a lack of laboratory tools. As it is a nonmodel organism, efforts to develop methods for sporulation and transformation have been sporadic and largely unsuccessful. Recent genome sequencing efforts are now providing B. bruxellensis researchers unprecedented access to gene catalogues, the possibility of performing transcriptomic studies and new insights into evolutionary drivers. This review summarises these findings, emphasises the rich data sets already available yet largely unexplored and looks over the horizon at what might be learnt soon through comprehensive population genomics of B. bruxellensis and related species. © 2014 Federation of European Microbiological Societies.

Varela C.,The Australian Wine Research Institute
Applied Microbiology and Biotechnology | Year: 2016

The conversion of fermentable sugars into alcohol during fermentation is the key process in the production of all alcoholic beverages. However, microbial activity during fermentation is considerably more complex than merely producing ethanol, usually involving the action of a great diversity of yeasts and bacteria and the production of metabolites that affect the organoleptic properties of fermented beverages. Non-Saccharomyces yeasts, which are naturally present in un-inoculated, spontaneous fermentations, can provide a means for increasing aroma and flavour diversity in fermented beverages. This review will cover the impacts of non-Saccharomyces yeasts on volatile composition and sensory profile of beer, wine, spirits and other fermented beverages, and look at future opportunities involving yeast interactions and regionality in alcoholic beverages. © 2016 Springer-Verlag Berlin Heidelberg

Borneman A.R.,The Australian Wine Research Institute | McCarthy J.M.,The Australian Wine Research Institute | Chambers P.J.,The Australian Wine Research Institute | Bartowsky E.J.,The Australian Wine Research Institute
BMC Genomics | Year: 2012

Background: Oenococcus oeni, a member of the lactic acid bacteria, is one of a limited number of microorganisms that not only survive, but actively proliferate in wine. It is also unusual as, unlike the majority of bacteria present in wine, it is beneficial to wine quality rather than causing spoilage. These benefits are realised primarily through catalysing malolactic fermentation, but also through imparting other positive sensory properties. However, many of these industrially-important secondary attributes have been shown to be strain-dependent and their genetic basis it yet to be determined.Results: In order to investigate the scale and scope of genetic variation in O. oeni, we have performed whole-genome sequencing on eleven strains of this bacterium, bringing the total number of strains for which genome sequences are available to fourteen. While any single strain of O. oeni was shown to contain around 1800 protein-coding genes, in-depth comparative annotation based on genomic synteny and protein orthology identified over 2800 orthologous open reading frames that comprise the pan genome of this species, and less than 1200 genes that make up the conserved genomic core present in all of the strains. The expansion of the pan genome relative to the coding potential of individual strains was shown to be due to the varied presence and location of multiple distinct bacteriophage sequences and also in various metabolic functions with potential impacts on the industrial performance of this species, including cell wall exopolysaccharide biosynthesis, sugar transport and utilisation and amino acid biosynthesis.Conclusions: By providing a large cohort of sequenced strains, this study provides a broad insight into the genetic variation present within O. oeni. This data is vital to understanding and harnessing the phenotypic variation present in this economically-important species. © 2012 Borneman et al.; licensee BioMed Central Ltd.

Contreras A.,The Australian Wine Research Institute | Curtin C.,The Australian Wine Research Institute | Varela C.,The Australian Wine Research Institute
Applied Microbiology and Biotechnology | Year: 2014

The wine sector is actively seeking strategies and technologies that facilitate the production of wines with lower alcohol content. One of the simplest approaches to achieve this aim would be the use of wine yeast strains which are less efficient at transforming grape sugars into ethanol; however, commercial wine yeasts have very similar ethanol yields. We recently demonstrated that Metschnikowia pulcherrima AWRI1149 was able to produce wine with reduced alcohol concentration when used in sequential inoculation with a wine strain of Saccharomyces cerevisiae. Here, different inoculation regimes were explored to study the effect of yeast population dynamics and potential yeast interactions on the metabolism of M. pulcherrima AWRI1149 during fermentation of non-sterile Shiraz must. Of all inoculation regimes tested, only ferments inoculated with M. pulcherrima AWRI1149 showed reduced ethanol concentration. Population dynamics revealed the presence of several indigenous yeast species and one of these, Saccharomyces uvarum (AWRI 2846), was able to produce wine with reduced ethanol concentration in sterile conditions. Both strains however, were inhibited when a combination of three non-Saccharomyces strains, Hanseniaspora uvarum AWRI863, Pichia kluyveri AWRI1896 and Torulaspora delbrueckii AWRI2845 were inoculated into must, indicating that the microbial community composition might impact on the growth of M. pulcherrima AWRI1149 and S. uvarum AWRI 2846. Our results indicate that mixed cultures of M. pulcherrima AWRI1149 and S. uvarum AWRI2846 enable an additional reduction of wine ethanol concentration compared to the same must fermented with either strain alone. This work thus provides a foundation to develop inoculation regimes for the successful application of non-cerevisiae yeast to the production of wines with reduced alcohol. © 2014, Springer-Verlag Berlin Heidelberg.

Cozzolino D.,The Australian Wine Research Institute
Combinatorial Chemistry and High Throughput Screening | Year: 2011

Chemical and physiological properties are related to individual or bioactive compounds such as essential oils terpenoids flavonoids volatile compounds and other chemicals which are present in natural products in low concentrations (e.g. ppm or ppb). For many years classical separation chromatographic and spectrometric techniques such as high performance liquid chromatography (HPLC) gas chromatography (GC) liquid chromatography (LC) and mass spectrometry (MS) have been used for the elucidation of isolated compounds from different matrices. Hence the use of standard separation chromatographic and spectrometric methods was found useful in chemical and both plant and animal physiology studies for fingerprinting and comparing natural and synthetic samples as well as to identify single active compounds. It has been generally accepted that a single analytical technique will not provide sufficient visualization of the metabolome hence holistic techniques are needed for comprehensive analysis. In the last 40 years near infrared (NIR) spectroscopy became one of the most attractive and used methods of analyzing agricultural related products and plant materials which provide simultaneous rapid and non-destructive quantitation of major. This technique has been reported to determine other minor compounds in plant materials such as volatile compounds and elements. The aim of this short review is to describe some recent applications of NIR spectroscopy combined with multivariate data analysis for high throughput screening of metabolites with an emphasis on food and medical applications. ©2011 Bentham Science Publishers Ltd.

Cozzolino D.,The Australian Wine Research Institute
Analytical and bioanalytical chemistry | Year: 2011

Information about constituents of grape juice, must, and wine can be used for management and decision support systems in order to improve, monitor, and adapt grape and wine production to new challenges. Numerous sensors that gather this information are either currently available or in development. Nevertheless there is still a need to adapt these sensors to special requirements, for example robustness, calibration and maintenance, operating costs, duration, sensitivity, and specificity to a particular application. The sensors commonly used by the wine industry are those that are based on mid-infrared (MIR), near-infrared (NIR), visible (VIS) and ultraviolet (UV) spectroscopy. This article reviews some recent technical solutions for analysis of juice, must and wine based on the combination of infrared spectroscopy and chemometrics.

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