Table 17.
Impact of stems during winemaking on total proanthocyanidin content (for each study, different letters indicate significant statistical differences).
| Grape Variety | Vintage | Modality | Maceration Time (days) | Total Proanthocyanidin (mg/L) |
|---|---|---|---|---|
| Method: Bate-Smith Reaction | ||||
| Cabernet [30] | 1966 | no stem addition | 4 | 1700 |
| stem addition | 2100 | |||
| Cabernet [30] | 1966 | no stem addition | 20 | 4200 |
| stem addition | 4500 | |||
| Cabernet [30] | 1967 | no stem addition | n.d. | 1700 |
| stem addition | 2000 | |||
| Malbec [30] | 1966 | no stem addition | 4 | 2400 |
| stem addition | 3500 | |||
| no stem addition | 8 | 3200 | ||
| stem addition | 3900 | |||
| no stem addition | 14 | 3500 | ||
| stem addition | 4500 | |||
| no stem addition | 30 | 3700 | ||
| stem addition | 4700 | |||
| Merlot [30] | 1966 | no stem addition | 8 | 2500 |
| stem addition | 4000 | |||
| Method: Vanillin Assay | ||||
| Primitivo [81] | 2012 | no stem addition | 10 | 1744a |
| 25% whole cluster | 2180b | |||
| 50% whole cluster | 2275b | |||
| Method: Precipitation Methods | ||||
| Cabernet sauvignon 1 [12] | 2013 | no stem addition | 15 | 403a |
| stem addition | 778b | |||
| Pinot Noir 2 [84] | 2014 | no stem addition | 10 | 370 |
| 20% whole cluster | 350 | |||
| Pinot Noir 2 [84] | 2015 | no stem addition | 10 | 540b |
| stem addition | 860c | |||
| 20% whole cluster | 440a | |||
| Pinot Noir 2 [83] | 2016 | no stem addition | 10 | 100a |
| 50% whole cluster | 210b | |||
| 100% whole cluster | 320c | |||
| dried stems | 325c | |||
| Pinot Noir 2 [83] | 2017 | no stem addition | 10 | 112a |
| 50% whole cluster | 175a | |||
| 100% whole cluster | 270c | |||
| dried stems | 275c | |||
1 Methyl cellulose precipitation. 2 Protein precipitation (mg/L catechin equivalent (CE).