Optimizing Grapes for Harvest: Timing and Techniques
The optimal time for harvesting grapes is critical for achieving the desired quality and flavor in winemaking. This article provides insights into when and how to harvest grapes, with a focus on the process of veraison and the importance of brix measurement.
Veraison: The Key Indicator
In the Northern Hemisphere, veraison begins to occur anytime from late June to mid-August, depending on the climate. In the Southern Hemisphere, this phase typically happens from January to February. Veraison is the ripening process during which the grapes soften and change color, marking the first sign that the grapes are on their way to ripeness. (Read more about veraison)
Signs of Ripeness
Grapes are typically ready to pick when they have reached full ripeness. The signs that indicate ripeness include changes in color, a slightly soft texture, and a sweet aroma. Different grape varieties ripen at different times, usually ranging from late summer to early fall. (Discover more about ripeness signs)
The How and When of Harvest Timing
The exact timing for picking grapes can vary greatly depending on the region and the style of wine being produced. For most varieties, it is best to harvest when the sugar level, measured in Brix, is between 22 and 24. However, the decision to pick is not always straightforward. (Read about Brix measurement)
Miscellaneous Considerations
Winemakers and grape growers need a few key tools and techniques to determine the optimal time for harvesting. One of the most crucial tools is a refractometer, which measures the level of soluble solids in the juice. (Explore how to use a refractometer)
Random Sampling Techniques
To ensure accuracy in sampling, follow these steps: Enter the vineyard and walk into any row. Stop by any random vine. Sample six to eight berries from all the clusters on every vine shoot you visit. Proceed down the row, sampling the same way from the opposite side of the row at a distance of 20 vines. Repeat this process, continuing until you have taken a sufficient number of samples. For a vineyard of 20 hectares, you should aim for at least 20 vines with 200 to 250 berries, or 40 vines with 600 berries.
Brix Measurement and Graphing
Start by sampling the grapes and crushing the fruit thoroughly. Place a drop of the juice in a strainer and draw off a sample. Place this drop on the screen of your refractometer. Ideally, you should start at a Brix level of 12 or 7 Beaume, 48 Oechsle, and repeat this sample every seven days, charting the rise in sugar levels. Plot these readings on a graph with Brix on the vertical axis and dates on the horizontal axis.
When you have three or four consecutive samples of increasing Brix levels (e.g., 12, 14, 16, 18), extend the line on the graph up to your desired sugar level and drop a line down to the horizontal axis. This will give you an approximate harvest date, allowing you to book the harvester or picking team.
Always remember that grapes are pretty predictable in their ripening curve, with weather challenges like rain or rot events being the main obstacles. Other factors like soil variations across the vineyard also play a role, but sugar levels are the primary parameter winemakers work with first.
Conclusion
Understanding veraison and how to measure Brix accurately are crucial for optimizing grape harvest timing. By utilizing the proper techniques, winemakers and growers can ensure they achieve the best quality and flavor in their wines.