Wines and Vines wrote today about some growing debate over the validity of the Adams-Harbertson assay.
In short, this is an assay that gives winemakers real-time quantitative and qualitative information about the tannins in their wines. However, the validity of the test is being challenged by winemaker Larry Brooks, Leo McCloskey and Doug Mckesson of Enologix and Marshall Sylvan – a University of California Santa Cruz mathematician and consultant to Enologix.
The assay was developed by two scientists at U.C. Davis: professor Dr. Douglas Adams and Dr. James Harbertson who was a UCD student at the time and is now affiliated with Washington State University. According to the Wines and Vines Article, the assay “has been adopted by several wineries and at least one commercial lab in California“.
The assay may serve winemakers by giving information necessary for tannin management, color stability and blending as well as age worthiness. A winemaker familiar with the assay (which requires an approximate $5,000 start-up layout for equipment – according to him) said it does not offer a specific indicator of a wine’s flags of ageability. Rather, the panel is analogous to a metabolic panel done in hospitals. It gives multiple parameters and data points. Observing any patterns in these indicators and seeing how they correlate with a wine’s evolution over time may yield hallmarks of age worthiness.
The Brooks paper challenging the validity of the assay cites “significant variation in results from trials at five labs“. The trials were conducted by a third party: Vinquiry Inc., a commercial enology lab. Vinquiry, however, has declined to comment on the results of their trials.
This variation may be intrinsic to the method or it may be operator-dependent. Training, competency or skill of the person performing any test impact its accuarcy. I see this in medical diagnostic imaging on a daily basis. But design flaws can doom the validity of a test as well.
One winemaker told me, off-line, that based on what they heard at a UCD seminar and read in a letter form an enologic laboratory, they believe that the Adams-Harbertson assay measures “tannins in juice but it could [not] correlate it with how much tannins you would end up in the wine” – which raises real questions of the test’s utility.
On the other side of the fence, a comment posted on the Wine and Vines article raises a possibility of a conflict of interest for the authors of the paper.
I invite all interested and informed on the matter to contribute to the discussion but request civil discourse.
[Larry Brooks has provided a copy of the paper in question.]
Email & Share