Sensory detection thresholds of "ladybird taint" in 'Riesling' and 'Pinot Noir' under different fermentation and processing conditions
DOI:
https://doi.org/10.5073/vitis.2012.51.27-32Keywords:
Harmonia axyridis, ladybird taint, wine processing, sensory detection thresholdAbstract
The Asian ladybird beetles Harmonia axyridis feed on damaged fruits in late summer and in autumn, especially on grapes. By getting harvested and processed together with the grapes, they cause an off-flavor in the wine, the so-called "ladybird taint" (LBT). Depending on fermentation conditions of red wine variety 'Pinot Noir', panelists recognized the LBT at different concentrations: Fewer beetles were required in the nonheated treatment to elicit LBT. The sensory detection threshold for LBT in must fermented wines was about 3 beetles·kg-1 of grapes and in must heated wines it was about 6 beetles·kg-1 of grapes. In the white wine variety 'Riesling', the sensory detection threshold for LBT was at 4 beetles·kg-1 of grapes. The main olfactory active compound causing LBT, 2-isopropyl-3-methoxypyrazine (IPMP), was detected by 50 % of panelists at a threshold of 1 ng·L-1 in 'Riesling' and 2 ng·L-1 in 'Pinot noir'. Thus, a threshold of five beetles with a specific amount of IPMP each in hemolymph processed within 1 kg of grapes can reach the human detection limit of 1-2 ng IPMP·L-1 of wine. Modifications in wine processing conditions can reduce the LBT in wines. The mortality of beetles in the wine press can be reduced at pressures less than 2 bar and duration of pressing shorter than 60 minutes.
Downloads
Published
Issue
Section
License
The content of VITIS is published under a Creative Commons Attribution 4.0 license. Any user is free to share and adapt (remix, transform, build upon) the content as long as the original publication is attributed (authors, title, year, journal, issue, pages) and any changes to the original are clearly labeled. We do not prohibit or charge a fee for reuse of published content. The use of general descriptive names, trade names, trademarks, and so forth in any publication herein, even if not specifically indicated, does not imply that these names are not protected by the relevant laws and regulations. The submitting author agrees to these terms on behalf of all co-authors when submitting a manuscript. Please be aware that this license cannot be revoked. All authors retain the copyright on their work and are able to enter into separate, additional contractual arrangements.