NCC Cork Audits
Following strict protocols, here are the most recent results of our audits.
Audited Quality Standards
The NCC conducts annual audits to verify that all approved QC protocols are observed. The foremost QC measure is screening for TCA, based on the GC/MS analytical method developed by ETS Laboratories. This analytical method is now widely used throughout the U.S., Europe, and Australia by members of both wine and cork industries. Other audited procedures involve moisture levels, physical integrity, residual oxidants and the maintenance of documentation.
The NCC Cork Sampling Program is Rigorous
For a typical lot of 100,000 corks NCC guidelines require a minimum sample of 250 corks taken from a selection of at least five separate bales. These corks are placed in 20-cork wine soaks for 24 hours to extract releasable TCA. Resulting soaks are analyzed using a method that reports TCA at concentrations as low as 1 part per trillion. If one of the five soaks indicates TCA at a threshold level – the entire cork lot is flagged and withheld from acceptance to inventory.
Incoming Natural Corks - Average TCA Score
NCC Audit Results - June 2023
Analysis of natural cork shipments continues to demonstrate a steady reduction in the occurrence of the chemical compound associated with taint. Since the adoption of its chemical testing method, the California based Natural Cork Council has screened every shipment of natural corks its members have brought to their warehouses. Before NCC members accept any cork lot into inventory, screening samples undergo GC/MS analysis of 2,4,6-Trichloroanisole (TCA). Any cork lots that fail testing requirements are rejected and removed from inventory.
Historic results show major reductions in TCA
Last year, NCC members conducted over 25,000 analyses. Their combined screening records show a steady reduction in measurable TCA levels that are now 99% lower than the results seen when records were first tabulated in 2001.
Incoming Natural Corks - Scores Less than 2ppt
NCC Audit Results - June 2023
Current Results from Screening of Incoming Cork Shipments Show 98.4% with Releasable TCA below 1ppt (ng/L).
The NCC screening protocol receives data with minimum reporting limit of “<1.0ppt”. The group has agreed to treat results below the MRL as “0.5ppt” for statistical purposes. Under this assumption, the group’s statistical records cannot improve below 0.5ppt.
Based on these screening results, approximately 1% of incoming natural cork lots were rejected by the NCC members prior to acceptance into inventory.