Volatile composition and sensory properties of Shiraz wines as affected by nitrogen supplementation and yeast species: rationalizing nitrogen modulation of wine aroma.
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.
The Australian Wine Research Institute, P.O. Box 197, Glen Osmond, South Australia 5064, Australia.
Maurizio
M
Ugliano
Brooke
B
Travis
I Leigh
IL
Francis
Paul A
PA
Henschke
D000328:Adult; D005260:Female; D005285:Fermentation; D005638:Fruit / Q000378:metabolism / Q000382:microbiology; D006801:Humans; D008297:Male; D009584:Nitrogen / Q000378:metabolism*; D012440:Saccharomyces / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D012903:Smell; D013649:Taste; D027843:Vitis / Q000378:metabolism / Q000382:microbiology*; D055549:Volatile Organic Compounds / Q000737:chemistry* / Q000378:metabolism; D014920:Wine / Q000032:analysis* / Q000382:microbiology
D055549:Volatile Organic Compounds; D009584:Nitrogen