Vineyard and Fermentation Studies To Elucidate the Origin of 1,8-Cineole in Australian Red Wine

Preliminary investigations revealed that the proximity of Eucalyptus trees to grapevines can directly influence the concentration of the aroma compound 1,8-cineole present in the corresponding red wines. For two different vineyards, the closer the grapevines were to the trees, the greater was the amount of 1,8-cineole in the wines elaborated from those grapes. This led us to carry out further studies to quantify the levels of 1,8-cineole found in grape berries, leaves, and stems at set distances from Eucalyptus trees over multiple vintages. Generally, the highest concentration of 1,8-cineole was found in the grapevine leaves, followed by grape stems and then grapes. In each sample type, we observed greater concentrations of 1,8-cineole in samples closer to the trees. Various fermentation treatments carried out with Shiraz grapes showed that matter other than grapes (MOG, e.g., Eucalyptus or grape leaves) could contribute significant amounts of 1,8-cineole to the finished wines. These studies confirmed that vineyard position and winemaking conditions can determine the 1,8-cineole concentration in red wine. The fermentation study also showed for the first time that the concentration of rotundone in red wine can be strongly influenced by grapevine leaves and stems in the ferment

Chiral Polyfunctional Thiols and Their Conjugated Precursors upon Winemaking with Five <i>Vitis vinifera</i> Sauvignon blanc Clones

Five co-located clones of Sauvignon blanc grapes were fermented under controlled conditions at laboratory-scale to investigate the impact of yeast strain, commercial enzyme, or nutrient addition on the concentrations of enantiomers of 3-sulfanylhexan-1-ol (3-SH) and 3-sulfanylhexyl acetate (3-SHA) in resulting wines. The relationship of these enantiomers with the odorless 3-SH precursors present in diastereomeric forms in grape juice was also examined. Possible variations may have existed due to clone type, not only for the diastereomers of 3-SH precursors in juices but also for the enantiomers of 3-SH and 3-SHA in the resulting wines, although there was no obvious stereochemical relationship between precursors and free thiols. From a flavor enhancement perspective, the use of a commercial enzyme in the juice significantly enhanced 3-SH production for some clones. In contrast, less impact on the production of 3-SH and 3-SHA was seen as a result of yeast strain and nutrient regardless of clone type

Fermentation chemistry analysis of wines using HPLC.

<p>Detection Limit 0.1g/L * g/L, ≠ % v/v Levels not connected by same letter are significantly different (p<0.05).</p

Grape juice fermentation profile of AWRI 838 and hybrid strains CxM1-CxM5.

<p><a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0062053#pone-0062053-g005" target="_blank">Figure 5a</a>. (top) Cell growth during fermentation as determined by Optical Density. Data points are presented with error bars. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0062053#pone-0062053-g005" target="_blank">Figure 5b</a>. (bottom) Sugar utilisation during fermentation as determined by Refractive Index. Data points are presented with error bars.</p

Solvent-extractable volatile fermentation products of AWRI 838, CXM1 and CXM4 in Chardonnay wines.

<p>Levels not connected by same letter are significantly different (p<0.05).</p

Primer sets and restriction endonucleases used to generate species-specific chromosomal markers.

<p>Primer sets and restriction endonucleases used to generate species-specific chromosomal markers.</p

Polyphenolic analysis of Chardonnay wines made by AWRI 838, CxM1 and CxM4 using UV Scan data: an index of Phenolic content.

<p>Levels not connected by same letter are significantly different (p<0.05).</p

Genetic stability of CxM4 fermentation isolates using chromosomal targeted PCR-RFLP.

<p>First gel Chromosome XIV left arm, second gel Chromosome XIV right arm, third gel Chromosome XVI left arm and fourth gel Chromosome XVI right arm. Fifth gel Chromosome XII left arm, sixth gel Chromosome XII right arm, seventh gel Chromosome XIV left arm. Lane 1 100 bp ladder, lane 2 AWRI838, Lane 3 NCYC2888, lane 4 DNA from both parents, lane 5 Hybrid CxM4, lanes 6 to 55 isolates 1 to 50. Arrows point to isolates with altered chromosomal content.</p

Target volatile fermentation products of AWRI 838, CXM1 and CXM4 in Chardonnay wines.

<p>Levels not connected by same letter are significantly different (p<0.05).</p

Sample sets of array-CGH data for parents and hybrid strain CxM1.

<p>Within each panel of microarray data, each column contains the a-CGH data for a given strain while each row corresponds to a probe for a chromosomal location. The leftmost three panels show the data for probes to the S. cerevisiae genome, located on chromosome V (“YD’ followed by chromosome coordinate), XIV (‘YN”), and XVI (”YP”); the rightmost three panels show data for probes to various regions (contig “c” followed by contig number) of the <i>S. mikatae</i> genome. 838 is the <i>S. cerevisiae</i> parent strain, AWRI 1529 is the <i>S. mikatae</i> parent strain NCYC2888, and AWRI2526 is the hybrid strain CxM1. Red hybridisation intensities for a probe indicate the presence of that species’ genome region, while green hybridisation intensities indicate the absence of that species’ genome region. The reduced intensity of <i>S. mikatae</i> probes in the hybrid dataset indicates a reduced <i>S. mikatae</i> ploidy level relative to <i>S. cerevisiae</i>, within the hybrid genome.</p