Winemaker Blog – When to Harvest?


Marquette (red wine) Grapes

HARVEST PARAMETERS. We have lots of grapes schedule to arrive this weekend at Train Wreck Winery. We will be harvesting our own Marquette, and we will be getting Frontenac and Frontenac Gris grapes from several growers.

How do we know when the grapes are ready to harvest? Science and experience. In a perfect world, there would arrive a moment when the sugar and acids were in just the right amounts. That seldom happens. So we pull sample clusters from the vineyard, trying to get a representative mix of clusters. Clusters that are exposed to the sun will ripen faster than those that may be shaded.

We press the juice out of this sample, and test for pH, sugar %(called “brix”) and sometimes other things such as titratable acidity(TA) or yeast assimilable nitrogen (YAN). Because of variablilities of rain, sun and growing degree days, the numbers we measure in the lab are seldom exactly what we are aiming for. And even though our lab tests might dictate waiting, we may see degradation in the quality of the grapes in the vineyard, or maybe we have to pick this weekend because next week is the big game and nobody will want to help pick. So we pick when the science, our experience, and our gut tells us the time is right.


Winemaker Blog – Brianna Harvest

SteveBottleWelcome to our Winemaker Blog.  Train Wreck Winery winemaker, Steve Larson, will share the experiences of growing and harvesting grapes, and the process of making wines.  Please follow along, ask questions, and if you enjoy the story, please share with your friends!

BRIANNA HARVEST. We picked our Brianna grapes on Saturday August 23d. The timing of harvest is based on the chemistry of the grape, as well as when we can get help to harvest. In the grape, we’re looking at sugar levels, pH, and total acidity.

BriannaFor the Brianna, I focus on the sugar level (expressed in degree Brix). Brix is actually a measure of dissolved solids, but virtually 100% of dissolved solids in grapes consists of sugar in the form of sucrose. For Brianna grapes, we’re looking for 15-17 Brix. If the sugar gets higher, this grape can develop aromas we don’t want. “Foxiness” is a term used for one of those aromas that we don’t want. Some use the term “cat-pee” instead of foxiness. Either way, sounds like something we want to avoid.

We’d like the pH of the grapes to be 3.2 if possible; our grape juice ended up at pH 3.05, with a Brix of 15.5. So we liked the sugar level, and can deal with the low pH. We harvested about 4,500 pounds from our half acre of Brianna, which is double our yield from last year. This yield resulted from a better-than-usual fruit set at bloom, and our intentional leaving of more buds at pruning this spring.

Because of mechanical difficulties with our destemmer, we brought the grapes to the winery and put them in our walk-in freezer at 28 degrees. The cold temp, along with the judicious addition of sulfite, keeps the berries fresh until processing.