1.Harvest Date Effects on Aroma Compounds in Aged Riesling Icewines.
Khairallah R1, Reynolds AG1, Bowen AJ1. J Sci Food Agric. 2016 Feb 1. doi: 10.1002/jsfa.7650. [Epub ahead of print]
BACKGROUND: Riesling icewine is an important product of the Ontario wine industry. The objective of this study was to characterize concentrations in aroma compounds in aged icewines associated with three harvest dates (H1, H2, H3) using stir bar sorptive extraction-gas chromatography-mass spectrometry and to make inferences, where appropriate, with respect to their roles in potential wine quality.
2.Antagonistic activity of fungi of Olea europaea L. against Colletotrichum acutatum.
Landum MC1, Félix Mdo R2, Alho J1, Garcia R1, Cabrita MJ2, Rei F2, Varanda CM3. Microbiol Res. 2016 Feb;183:100-8. doi: 10.1016/j.micres.2015.12.001. Epub 2015 Dec 12.
Fungi naturally present in olive trees were identified and tested for their antagonistic potential against Colletotrichum acutatum. A total of 14 isolates were identified, 12 belonged to genera Alternaria, Epicoccum, Fusarium, Aspergillus, Anthrinium, Chaetomium, Diaporthe, Nigrospora, one to family Xylariaceae and one was unclassified. All fungal isolates showed some inhibitory action over the growth of C. acutatum during dual culture growth, however, when agar-diffusible tests were performed only five fungal isolates caused C. acutatum growth inhibition: Alternaria sp. isolate 2 (26.8%), the fungus from Xylariaceae family (14.3%), Alternaria sp. isolate 1 (10.7%); Diaporthe sp. (10.7%), Nigrospora oryzae (3.5%). Volatile substances produced by these isolates were identified through gas-chromatography techniques, as phenylethyl alcohol, 4-methylquinazoline, benzothiazole, benzyl alcohol, lilial, galaxolide, among others. These inhibitory volatiles could play a significant role in reduction of C.
3.GC-MS Metabolite Profiling of Extreme Southern Pinot noir Wines: Effects of Vintage, Barrel Maturation, and Fermentation Dominate over Vineyard Site and Clone Selection.
Schueuermann C1, Khakimov B2, Engelsen SB2, Bremer P1, Silcock P1. J Agric Food Chem. 2016 Mar 23;64(11):2342-51. doi: 10.1021/acs.jafc.5b05861. Epub 2016 Mar 8.
Wine is an extremely complex beverage that contains a multitude of volatile and nonvolatile compounds. This study investiged the effect of vineyard site and grapevine clone on the volatile profiles of commercially produced Pinot noir wines from central Otago, New Zealand. Volatile metabolites in Pinot noir wines produced from five grapevine clones grown on six vineyard sites in close proximity, over two consecutive vintages, were surveyed using gas chromatography-mass spectrometry (GC-MS). The raw GC-MS data were processed using parallel factor analysis (PARAFAC2), and final metabolite data were analyzed by principal component analysis (PCA). Winemaking conditions, vintage, and barrel maturation were found to be the most dominant factors. The effects of vineyard site and clone were mostly vintage dependent. Although four compounds including β-citronellol, homovanillyl alcohol, N-(3-methylbutyl)acetamide, and N-(2-phenylethyl)acetamide discriminated the vineyard sites independent of vintage, Pinot noir wines from different clones were only partially discriminated by PCA, and marker compound selection remained challenging.
4.Effect of yeast assimilable nitrogen on the synthesis of phenolic aroma compounds by Hanseniaspora vineae strains.
Martin V1, Boido E1, Giorello F1, Mas A2, Dellacassa E3, Carrau F1. Yeast. 2016 Mar 5. doi: 10.1002/yea.3159. [Epub ahead of print]
In several grape varieties the dominating aryl alkyl alcohols found are the volatile group of phenylpropanoids related compounds, such as glycosylated benzyl and 2-phenylethyl alcohol, which contribute to wine with floral and fruity aroma after being hydrolyzed during fermentation. Saccharomyces cerevisiae is largely recognized as the main agent in grape must fermentation, but yeast strains belonging to other genera, including Hanseniaspora, are known to predominate during the first stages of alcoholic fermentation. Although non-Saccharomyces yeast strains have a well-recognized genetic diversity, the understanding of their impact on wine flavor richness is still incipient. In this work, eleven Hansenisapora vineae strains were used to ferment a chemically defined simil-grape fermentation medium, resembling the nutrient composition of grape juice but devoid of grape derived secondary metabolites. GC-MS analysis was performed to determine volatile compounds in the produced wines.