|
||
| What Flavor Is Linked To the 100-Point Score? (Hint: High Precision Tannin Measurment From Enologix.) | ||
| Tannin Measurements With A Precision Found Only In Medicine Are Sold by Enologix To Calculate 100-point Scores In Napa Valley. | ||
| Excepts from Journal of Association of Official Analytical Chemists | ||
|
One important phenolic is Tannin. It is less important to say it is produced by grape seeds, than it is linked to the price of wine. One comes to the importance of tannin when one tastes Napa Valley Cabernet Sauvignon with 90-plus-point scores. Nearly every one of these 90-point wines contains more Tannin than the average supermarket wine; which is more than 1,000 parts per million (ppm). It is there when one looks deep into the 1855 Classification of Bordeaux, again 1000 ppm break. Enologix analytics include Tannin; we use it o compute our core quality index which accounts for up to 80% of the variation in the 100-point score and winemakers blind tasting scores, too. To stagger together through the sensory analysis of linking Tannin to taste, much less 100-point scores, suffice to say Tannin measurement must be highly accurate, and for several reasons. One must link Tannin to human taste, blind tastings, where differences of 10% are detectable my tasters. Winemakers must track Tannin over time to improve concentrations and tasting scores. One could quite easily lower one’s 100-point score using invalid mesurements. Bad science makes good winemaking impossible. Tannin measurements must have a precision of the medical industry (Defined by chemists as Validity and Reliability). Changes of 10%, cannot be detected by a method with an Error of more than 10%. As change of 10% is the difference between 89- and 90-points. Association of Official Analytical Chemists (AOAC) documented the poor precision of the most widely used commercial tannin assay which were proposed for commercial winemaking, thereby creating the real possibility of quality control problems here in California. Five laboratories used this tannin method to assay bottled wines (n = 135) found in California supermarkets, with tannin concentrations of nominally 500 and 1000 parts per million. They compared their laboratories’ to the commercial results. Journal of AOAC documented the poor precision. Reliability exceeded the +/-5% industry requirement by nominally 5 times (z-score based on 5% distribution). Coefficient of variation was +/-27%, making the standard deviation range 54% for Pinot Noir, 34% for Merlot, and 44% for Cabernet Sauvignon. Intralaboratory validity recovery was 55-63%. Interwinery validity was 71-178% of the mean for Pinot Noir, 81-144% for Merlot, and 83-164% for Cabernet Sauvignon. Range as a function of the mean was 89% for Pinot Noir, 55% for Merlot, and 67% for Cabernet Sauvignon. Expect intermethod validity to be nominally 50%, i.e., percent recovery to HPLC. These statistically significant errors were predicted by the literature. Winemakers using the measurements risk making wines that are relatively more tannic than the measurements report. Laboratory Genius (Hint: It Is Precision.) Reference: J AOAC Int. 2008 Sep-Oct;91(5):1090-4. Adams-Harbertson protein precipitation-based wine tannin method found invalid. Brooks L, McCloskey L, McKesson D, Sylvan M. Source LM Brooks Consulting, 979 Osos St, Suite C-l, San Luis Obispo, CA 93401, USA. lmbrooks@pacbell.net |
Tweet 
|
|