Harvest timing is always a balancing act between winemakers who want the best, most mature fruit flavors and growers who need to manage labor and protect the fragile, ripe fruit from damage and disease.
Traditionally, winemakers praise long hang times for both consolidating sugars and developing flavors, but new research from Washington State University shows that fruit maturity affects the former far more than the latter.
It’s a new insight that could help growers and winemakers understand when to pick and why — depending on what kind of wine they hope to make, said enology professor Jim Harbertson.
“The picking decision aspect of wine making is so critical. You can’t put the fruit back on the vine,” he said. “It represents one of the most important decisions that winemakers make. So, we’re trying to understand why.”
Winemaking is a mix of art and science, and some traditional practices remain poorly understood. Harbertson said his research is focused on understanding why wine works the way it does, so that growers and winemakers can make more informed decisions.
In the case of hang time, he found that for Merlot, fruit at higher Brix levels resulted in better wine. But the reason why may surprise many winemakers who swear by the practice.
For his experiments, Harbertson made wine from unripe, ripe and overripe Merlot grapes. He found that many of the flavors associated with ripe fruit are developed surprisingly early in the season.
He could coax the same flavors out of unripe grapes (20 degrees Brix) as those picked 60 days later (27 degrees Brix) with supplemental sugar during the winemaking process, according to sensory analysis.
So rather than hang time affecting development of key flavor compounds, it affects the fruit sugar level instead, which leads to the resulting wine’s alcohol content. That matters because the higher alcohol content enhances the expression of those flavor and aroma compounds, Harbertson said.
He found that the reverse is true as well. Wine made with ripe fruit that’s watered back to a lower alcohol level can develop the “veggie” taste sometimes associated with unripe Merlot.
“Winemakers tell us that when the fruit gets riper, there’s changes in these compounds. But we found that it’s less important than that huge dollop of alcohol there,” from the sugar consolidation in the fruit, he said. “High alcohol wine tastes like ‘ripe fruit’ wine.”
But he’s not advocating for adding extra sweeteners. That process, known as chaptalization, has long been employed to improve wines in regions where it’s hard for grapes to fully ripen, but it’s carefully regulated or banned in many wine regions.
Instead, he said the research just offers insight into why many consumers are enjoying the higher alcohol, big color and bold flavor red wines that Eastern Washington can produce well.
And it lends support to the commonly used Brix test as the best tool for helping growers and winemakers make the best harvest decisions.
Not everyone embraces higher alcohol wines, but the trend could be around for awhile. Harbertson presented the results of his study at a WSU symposium on climate extremes and the potential impact on the Pacific Northwest’s wine industry. He said that warming temperatures and longer growing seasons can lead to riper fruit.
“We’ve been making high alcohol wines for quite some time, as a result of this region getting warmer and warmer,” he said. “Modern winemaking is a response to climate change.”
Harbertson intends to continue these experiments to look at Cabernet Sauvignon and narrow in on the specific flavor compounds creating the ripe fruit aromas. •
– by Kate Prengaman