Cork Taint Issues

CQC Study of Technical Cork Performance

Study of the transfer of TCA to bottled wine with various components used in the manufacture of technical corks - February 2010 

Summary : Results of a 24-month bottling study of wines bottled with technical corks made with a variety of components. Technical corks representing current producion produce no reportable TCA in bottled wine. Low TCA disks successfully inhibited TCA migration from aggloerated bodies high in TCA.      

ETS/CQC Study on Releasable TCA
Study of the interaction between cork, wine and TCA Presented by ETS/CQC at the ASEV Annual Meeting - July 1999 - Reno NV

Summary : Report of the development of GC/MS SPME analysis of TCA in cork soaks. This study established links correlations between TCA observed in group cork soaks with transmission of TCA to bottled wine. The work introduced the term "Releasable TCA" and has proved to be the foundation of quality control programs throughout the worldwide cork industry.                                    

Results of CQC Incoming Cork Testing
A Successful Application of Chemical Cork Screening Methods Presented by Peter Weber CQC - APCOR Cork Seminar - June 2006 - St. Helena CA

Summary : A statistical analysis from 50,000 group cork soaks over the past four years. The report illustrates that the vast majority of CQC natural corks are now below 2ppt (94%). Presents details on new, more stringent screening techniques that are designed to identify bales with a majority clean corks but with small percentages (1-3%) of high TCA corks. Such cork populations are now rejected at the “lot level” – not just the individual bale that reveals a higher score.

AVF Study on Population Statistics
Screening natural corks by their releasable TCA : Does it Work? Presented by Eric Herve PhD, ETS Laboratories - Sponsored by the AVF - APCOR Cork Seminar - June 2006 - St. Helena CA

Summary: Demonstrated that group cork soaks accurately portray the average of the individual corks. Further showed that these average scores can are closely related to TCA concentration in bottled wines. Summarizes that group cork soaks are a valid QC tool. Illustrates that low TCA Bales produced very small percentages of cork taint.

Sensory Detection of TCA in Wine
Estimating a ‘‘consumer rejection threshold’’ for cork taint in white wine John Prescott, Leslie Norris, Madeleine Kunst, Sandra Kim - "Food Quality and Preference"

Summary: Two consumer studies - one triangle test was designed to identify the detection level of TCA in white wine (2.1ppt) - the second was a sequential test designed to identifiy what concentration of TCA caused consumers to prefer the control over the spiked sample (3.1ppt).

CQC Study of Chemical Origins of Off-Aromas in Wines
Analysis of rejected wines at Sonoma County Harvest Fair Presented by Peter Weber CQC - ASEV Eastern Meeting - June 2003 - Lancaster PA

Summary: Study compared 40 wines rejected by judges for off-aromas to the accepted control sample. Eight compounds commonly associated with cork defects were analyzed. Only TCA showed correlation to sensory rejection. The other seven compounds were either not measurable, or found in equal frequency between the rejected wines and the acceptable controls.