PHENOLIC RIPENESS IN SOUTH AFRICA by Dr AHA …

1 By Dr AHA Roediger assignment submitted in partial requirement for Cape Wine Masters Diploma Stellenbosch July 2006 i Absorbance Abs Anthocyanin extractability Ea Australian dollar AU$ Cabernet Franc CF Cabernet Sauvignon CS Folin-Ciocalteau FC Gallic acid equivalents GAE High Pressure Liquid Chromatograph HPLC Institut Cooper ratif du Vin ICV Malbec MAL Merlot MO Near-infrared NIR Pinotage PI Pip tannins in percentage Mp Revolutions per minute rpm Shiraz SH Total acidity TA Total phenol content (determined by Glories method) PFT Total PHENOLIC index TPI University of Stellenbosch US ii LIST OF CONTENTS Sugar Physiological !

2 PHENOLIC acids and their Taste and mouth feel of PHENOLIC " # Determination of sugar Other methods used to determine RIPENESS (excluding analysis of PHENOLIC compounds)..15 pH of grape juice ..15 Sugar/acidity ratio in grape Malic acid vs. tartaric Berry Arginine levels ..19 Grape ripening (physical parameters)..19 Grape tasting using the Institut Coop ratif du Vin (ICV) Grape tasting using the Gironde method ..22 Near-infrared Methods of determining the PHENOLIC Folin-Ciocalteau Patrick Iland Roger Boulton Glories method.

3 25 # $ Chile ..27 Spain, Italy, Italy, Sicily ..29 France, Tunisia and iii In SOUTH Wine estates and wine % & " $ ' ( $ Various methods used to analyse PHENOLIC Patrick Iland Glories method ..42 Typical examples of results of PHENOLIC RIPENESS Ripening process and the quality of grapes ..46 Influence of water on grape quality ..52 The influence of topping and bunch thinning on grape Influence of temperature on anthocyanin Optimising the Glories Glories vs.)

4 Iland Comparison of anthocyanins evaluated in grapes and in resultant wine ) &* ( , * , - %% SOUTH Carneros (California) ..74 ! ) Conclusions ). Recommendations ) . )# iv LIST OF FIGURES Figure 1: General trends of the traditional variants: sugar, acidity and pH, monitored during grape ripening, adapted from Rotter [3]. 5 Figure 2: General trends in various fruit features during ripening, adapted from Rotter [3].

5 7 Figure 3: Trends in tannin contents and skin colour during ripening, adapted from Rotter [3]. 8 Figure 4: Correlation of concentration of anthocyanins vs. wine quality in Pinotage [23]. 14 Figure 5: Changes in acidity during ripening, adapted from Bisson [2]. 17 Figure 6: Graph indicating the calibration curve of absorbance versus gallic acid concentration. 40 Figure 7: and A1 Jordan block M3 [CS] 2003 48 Figure 8: A1 Jordan blocks M3 and 38 [CS] 2003. 48 Figure 9: and A1 Kanonkop Estate block 103 [CS] 2003.

6 48 Figure 10: Sugar RIPENESS Kanonkop Estate block 103 [CS] 2003 48 Figure 11: PFT (Glories method) Kanonkop Estate block 103 [CS] 2003. 50 Figure 12: GAE (FC method) Kanonkop Estate block 103 [CS] 2003. 50 Figure 13: A1 Lanzerac blocks D7A and CF3 [CF] 2003. 50 Figure 14: Ea Lanzerac block D7A and CF3 [CF] 2003. 50 Figure 15: and A1 Rust en Vrede block X [SH] 2004. 51 Figure 16: and A1 Jordan block M3 [CS] 2004. 53 Figure 17: A1 De Toren Private Cellar [CS] 2005.

7 55 Figure 18: A1 Jordan block M3 [CS] 2003-2005. 55 Figure 19: A1 Blue Creek block BC [CS] 2003-2005. 55 Figure 20: and A1 Zorgvliet block C5 [SH] 2005 59 Figure 21: and A1 Zorgvliet block C5 (bunch thinned) [SH] 2005 59 Figure 22: % extractability at pH 1 and pH against hours extracted 62 Figure 23: % anthocyanin extractability and % contribution of the tannins from the seeds to the phenol content against hours extracted. 62 Figure 24: % extractability at pH 1 and pH vs.

8 Time mashed (sec) 62 Figure 25: % extractability and contribution of seed tannins vs. time mashed (sec). 62 Figure 26: A1 grapes and wine De Toren Private Cellar block D [CS] 2005. 64 v LIST OF TABLES Table 1: The 20 descriptors used in the ICV berry tasting method 20 Table 2: Results of Glories method analyses, illustrating examples of analyses carried out in Spain [50] 28 Table 3: Analytical data for Rioja, 2003 vintage rating, using TPI 28 Table 4: Analytical data for Rioja, 1995-2003 vintage rating, using TPI 29 Table 5: PHENOLIC RIPENESS results from Fairview, as determined by the Glories method 32 Table 6.

9 Data obtained from Kanonkop Estate to draw up a calibration curve for GAE analysis 39 Table 7: Results of the absorbencies of grape samples and a blank, illustrating the GAE analysis 40 Table 8: Results illustrating the absorbencies used for the calculations of Kanonkop Estate Block 103 to determine the PHENOLIC RIPENESS by the Glories method 45 Table 9: Glories data obtained, Jordan block M3 [CS] 2003 46 Table 10: Glories and GAE data obtained, Tokara block R3 [CS] 2004 51 Table 11: Glories data obtained for KWV Limited, Marklew Family Wines [71] [PI] 2006 52 Table 12: Glories data obtained, Jordan block 38 [CS] 2005 53 Table 13: Glories data obtained, Buitenzicht block 6 [SH] 2005 53 Table 14: Glories data obtained, Blue Creek block BC1 [CS] 2005 54 Table 15: Glories data obtained, Kaapzicht [MO] 2004 56 Table 16.

10 Glories and GAE data obtained, Kanonkop Estate block 103 [CS] 2004 58 Table 17: Glories data obtained, Zorgvliet block C5 [SH] 2005 59 Table 18: Variables modified to optimise the Glories method, Roos [79] block E2 [SH] 2004 60 Table 19: Glories data obtained using two different types of blenders, Eagles Nest 2006 61 Table 20: Comparison of Iland and Glories method, Eagles Nest [MO] 2006 63 Table 21: A1 of various blocks and resulting wines, De Toren 2005 64 Table 22: Grape quality categories based on A1 results as determined by the Glories method 80 1 The study of PHENOLIC RIPENESS is an extremely complicated field including what to study and how to use results.