Screening Natural Corks by Their Releasable TCA: Does it Work? Eric Hervé Ph.D. E T S Laboratories, St. Helena, CA 1 1. What is Releasable TCA?. RTCA from bulk vs. individual cork soaks 3. Bulk Soaks as a screening tool. Relation with bottled wine TCA 1
1. What is Releasable TCA?. Bulk Soaks as a screening tool 3. RTCA from bulk vs. individual cork soaks. Relation with bottled wine TCA 3 Releasable TCA Traditional QC Cork soaks + sensory
Releasable TCA CA TCA Extraction Headspace/SPME: Environmentally-friendly Selective extraction volatile compounds Precision (if correct IS) Automation 5 Releasable TCA TCA Analysis Gas Chromatography / Mass Spectrometry: Selective detection Sensitivity High throughput (+ / h) 3
Releasable TCA.. TCA (ng/l).... B1 (.9) B9 (.9) B15 (.5) B (7.) B9 (.9) B3 (11.).. 7 9 Time (hours) Kinetics of cork soaks: equilibrium 7 Releasable TCA Releasable TCA (RTCA) For a cork, or group of corks, the concentration of TCA reached at equilibrium in a wine soak. Expressed in ng/l (or ppt). (Hervé E., Price S. and Burns G. - ASEV 1999)
1. What is Releasable TCA?. RTCA from bulk vs. individual cork soaks 3. Bulk Soaks as a screening tool. Relation with bottled wine TCA 9 Bulk (group) soaks Individual soaks 5
Individual Cork Soaks. Labor intensive, costly. Sensory evaluation only. Excessively large lot sizes 11 Bulk Cork Soaks. TCA analysis possible, but. Good corks may absorb TCA. Doesn t tell % of bad corks
AVF Study Bales commercial corks pre-selected (bulk 5 RTCA low to high) Each Bale x individual cork RTCA (distribution) x bulk 5 cork RTCA (precision) x bottled wine TCA (validation) 13 Mean Bulk-5 Corks RTCA (ng/l)....... y =.79x +.7 R =.9....... Mean Individual Corks RTCA (ng/l) Bulk vs. individual soaks: correlation of the means 7
Releasable TCA (ng/l) 19 1 17 15 13 11 9 7 5 3 1 Bale G: 3. ng/l No clear-cut line good cork / bad cork Individual Corks 15 Releasable TCA (ng/l) 19 1 17 15 13 11 9 7 5 3 1 Bale B:.9 ng/l (low) Bulk 5 RTCA scores relate to distribution patterns Individual Corks
Releasable TCA (ng/l) 19 1 17 15 13 11 9 7 5 3 1 Bale G: 3. ng/l (high) Bulk 5 RTCA scores relate to distribution patterns Individual Corks 17 Releasable TCA (ng/l) 19 1 17 15 13 11 9 7 5 3 1 Bale J: 9. ng/l (very high) Bulk 5 RTCA scores relate to distribution patterns Individual Corks 1 9
1. What is Releasable TCA?. RTCA from bulk vs. individual cork soaks 3. Bulk Soaks as a screening tool. Relation with bottled wine TCA 19 Screening Tool 5-Cork Bulk Soak RTCA (ng/l) 1 B A D C G F E H I 1 3 5 7 9 11 Average Individual Cork RTCA (ng/l) Bulk 5 cork soak: dispersion of the tests J
Screening Tool 5-Cork Bulk Soak RTCA (ng/l) 1 Arbitrary cut-off point 1 3 5 7 9 11 Average Individual Cork RTCA (ng/l) 1 Screening Tool 5-Cork Bulk Soak RTCA (ng/l) 1 Arbitrary cut-off point Rejected Accepted 1 3 5 7 9 11 Average Individual Cork RTCA (ng/l) 11
Screening Tool 5-Cork Bulk Soak RTCA (ng/l) 1 borderline bales: 5/5 1 3 5 7 9 11 Average Individual Cork RTCA (ng/l) 3 Screening Tool 5-Cork Bulk Soak RTCA (ng/l) 1 lower bales: few tests above limit 1 3 5 7 9 11 Average Individual Cork RTCA (ng/l)
Screening Tool 5-Cork Bulk Soak RTCA (ng/l) higher bales: very few tests below limit 1 1 3 5 7 9 11 Average Individual Cork RTCA (ng/l) 5.5 Average RTCA of Group Corks Soaks from CQC Screening Program. 3.5 3..5. 1.5 1..5 Q 1 Q1 Q Q3 Q Q1 3 Releasable TCA (ppt) Q 3 Q3 3 Q 3 Q1 Q Q3 Q Q1 5 Q 5 Q3 5 7% decline since end 1 Average soaks (1) 13
1. What is Releasable TCA?. RTCA from bulk vs. individual cork soaks 3. Bulk Soaks as a screening tool. Relation with bottled wine TCA 7 Screening Tool Ongoing Study Bales commercial corks: pre-selected (bulk 5 RTCA low to high) Each Bale: x individual cork RTCA (populations) x bulk 5 cork RTCA (precision) x bottled wine TCA (after storage)
Bottled Wine After 9 months: bottles/bale analyzed Arbitrary Classes Probable Sensory Effect 1 - ng/l possibly muted - ng/l muted - ng/l moderately corked > ng/l corked 9 Bottled Wine Bottle TCA after 9 months Bottle Occurence (%) 35 3 5 15 1- ng/l "possibly muted" - ng/l "muted" - ng/l "moderately corked" + ng/l "corked" 5 A (.) B (.9) C (1.) D (.) E (.) F (.) G (3.) H (.1) I (7.) J (9.) Bale ID (RTCA ng/l) 3 15
Thanks To: The American Vineyard Foundation The Natural Cork Quality Council Beringer Blass Wine Estates 31