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J Agric Food Chem

Title:		Volatile composition and sensory properties of Shiraz wines as affected by nitrogen supplementation and yeast species: rationalizing nitrogen modulation of wine aroma
Author(s):		Ugliano M; Travis B; Francis IL; Henschke PA;
Address:		"The Australian Wine Research Institute, P.O. Box 197, Glen Osmond, South Australia 5064, Australia"
Journal Title:		J Agric Food Chem
Year:		2010
Volume:		20101110
Issue:		23
Page Number:		12417 - 12425
DOI:		10.1021/jf1027137
ISSN/ISBN:		1520-5118 (Electronic) 0021-8561 (Linking)
Abstract:		"The effects of yeast assimilable nitrogen (YAN) supplementation on Shiraz volatile composition and sensory properties have been investigated. A low YAN Shiraz must (YAN 100 mg/L) was supplemented with nitrogen in the form of diammonium phosphate (DAP) to a final YAN of either 250 or 400 mg/L. Fermentation was carried out with either Saccharomyces cerevisiae or Saccharomyces bayanus , with maceration on skins. For both yeast strains, high DAP additions increased the ratings of positive sensory attributes such as 'red fruit' and 'dark fruit' and decreased the 'yeast/cheese', 'vegetal', and 'earth/dirty' attributes. For the S. cerevisiae yeast moderate DAP addition resulted in higher 'reduced' attribute scores. DAP supplementation had a strong influence on formation of acetates, fatty acid ethyl esters, higher alcohols, hydrogen sulfide, ethyl mercaptan, methyl mercaptan, DMS, and DES. Partial least-squares regression analysis of chemical and sensory data indicated that esters, sulfides, and mercaptans were associated with fruit-related descriptors, whereas hydrogen sulfide was associated with the 'reduced' attribute. Nitrogen-related variations in the concentration of other yeast metabolites such as ethanol and 2- and 3-methylbutanoic acids also affected perceived fruitiness. Depending on yeast species DAP supplementation to a low nitrogen must can result in increased reduction off-odor"
Keywords:		Adult Female Fermentation Fruit/metabolism/microbiology Humans Male Nitrogen/*metabolism Saccharomyces/*metabolism Saccharomyces cerevisiae/*metabolism Smell Taste Vitis/metabolism/*microbiology Volatile Organic Compounds/*chemistry/metabolism Wine/*analy;
Notes:		"MedlineUgliano, Maurizio Travis, Brooke Francis, I Leigh Henschke, Paul A eng Research Support, Non-U.S. Gov't 2010/11/12 J Agric Food Chem. 2010 Dec 8; 58(23):12417-25. doi: 10.1021/jf1027137. Epub 2010 Nov 10"