Aroma compounds in Ontario Vidal and Riesling icewines. I. Effects of harvest date

• Published in: Food research international 2015-10, Vol.76 (Pt 3), p.540-549
• Main Authors: Bowen, Amy J., Reynolds, Andrew G.
• Format: Article
• Language: English
• Subjects: Gas chromatography; Mass spectrometry; Monoterpenes; Norisoprenoids; Odor-potent compounds
• ISSN: 0963-9969; 1873-7145
• DOI: 10.1016/j.foodres.2015.06.046

Icewine is a sweet dessert wine made from pressing grapes naturally frozen on the vines. It is likely that freeze/thaw cycles endured by icewine grapes change their chemical and sensory profiles due to climatic events. Our objective was to determine the influence of harvest date on icewine must and wine basic chemical variables and aroma compounds. Riesling and Vidal icewines were made from grapes picked between December 2004 and February 2005; Harvest 1 (H1): 19 December; Harvest 2: 29 December; Harvest 3 (H3): 18 January; and Harvest 4 (H4): 11 February (Vidal only). Icewine musts differed in titratable acidity and pH (Vidal only). All basic wine chemical analytes differed across harvest dates. All aroma compounds differed in Vidal and Riesling wines. Highest concentrations for most aroma compounds were in the last harvest date; 16 of 24 for Vidal and 17 of 23 for Riesling. The latest harvest date had highest ethyl isobutyrate, ethyl 3-methylbutyrate, 1-hexanol, 1-octen-3-ol, 1-octanol, cis-rose oxide, nerol oxide, ethyl benzoate, ethyl phenylacetate, γ-nonalactone and β-damascenone. H1 had highest ethyl butyrate, ethyl hexanoate, linalool, 4-vinylguaiacol and ethyl octanoate. Based on odor activity values, the most odor-potent compounds were β-damascenone, cis-rose oxide, 1-octen-3-ol, ethyl octanoate, ethyl hexanoate, and 4-vinylguaiacol across harvest dates. PCA found most aroma compounds associated with the last harvest date, 4-vinylguaicol excepted, which was associated with H1. Harvest date was considered a discriminating dimension using canonical variant analysis for volatile compounds. •Riesling and Vidal icewines were made from grapes harvested on 4 dates (H1–H4; Dec. 2004–Feb. 2005).•Highest aroma compound concentrations were in H3/H4 wines; 16 of 24 (Vidal H4) and 17 of 23 (Riesling H3).•Compounds highest in H3/H4 included: cis-rose oxide, nerol oxide, γ-nonalactone, and β-damascenone.•H1 had highest ethyl butyrate, ethyl hexanoate, linalool, 4-vinylguaiacol, and ethyl octanoate.•Most odor-potent compounds included: β-damascenone, cis-rose oxide, 1-octen-3-ol, and ethyl octanoate.