It’s finally here. Harvest. We’re starting to see trucks of grapes rolling down the highways and backroads of wine country. This is an exciting time, of course. It’s also one full of tension and stress for winemakers and grapegrowers – especially this year. With the cool summer that Northern California experienced, we’re way behind.
So, how do we know when it’s the right time to pick? Well, there are several factors.
Let’s start with the easiest. Sugar or Brix in wine making terms. The sugar content in grapes is generally measured in degrees of Brix. One degree of Brix is equal to one gram of sucrose for every 100 milligrams of solution. Okay, let’s not get all crazy with the chemistry (because I wasn’t ever good at it), but it’s important to know.
Table grapes (you know, the kind at the grocery store) are usually picked at about 13-15 Brix. Wine grapes, however, are picked at a much higher sugar level. Generally around 23-26 Brix, depending on the grape varietal. This will yield finished alcohol levels in the 13.5 – 16% range.
By far, Brix is the most important factor in determining when to pick. The sugar level in the grapes directly affects the alcohol level in the finished wine. Why is that important? Believe it or not, if the alcohol level isn’t high enough, the wine will be unbalanced. In recent years, some winemakers have been trying to increase alcohol levels by letting the grapes hang on the vines longer to extract more flavor. This is great for some types of grapes and some wines, but not all benefit from this extended time.
This year things are different. Grape growers in Northern California have been struggling to get the sugar levels up high enough to even think about picking. It’s more like France this year then ever before. France is known for long, cool summers that allow for slow ripening of the grapes. But usually France has to pick early before sugar levels are high enough to create balanced wines. But they counteract this by adding sugar cane during the fermentation process. The added sugar increases the alcohol levels making the wine more balanced. Here in the U.S. that is not legal. So, if we can’t get the sugars up naturally, it can be devastating.
Acid and pH
Acid and pH are two other important factors in determining when to pick. I’m not going to go into too much detail here, but there are several acids naturally occurring in wine grapes: tartaric, malic and citric are the most common. Measuring these (acid and pH) are important because they will help determine the balance in the final wine. It’s imperative to pick when the grapes are balanced because you can’t fix that in the cellar.
What is all this balance I’m talking about? Think of balance as basically all the components working in harmony together. Think of it as that “AAAAHHHHHH” moment where the light shines and all is good with the world. Okay, maybe that’s a little hokey, but hopefully it brings it home for you.
Crushing or Pressing
Let’s say the winemaker / vineyard manager say, “pick!”. What next? Crushing the grapes. There are many ways to do this, but I’ll quickly go through the most common one.
The grapes arrive at the crush pad, either by 1/2 ton macro bins or two ton “valley” bins. Clearly, these bins contain about 1000 lbs and 4000 lbs, respectively. Does it make a difference? Well, it can. With the smaller bins less grapes are harmed in the travel since there’s less pressure on them. In most cases, it’s pretty insignificant.
The grapes will then go into a hopper that leads into a crusher / de-stemmer. This machine takes the grapes off the stems and crushes them by cracking the skin of the grapes. The result is what’s called free-run juice. In the case of a white wine, the grapes will be separated from the juice almost immediately. For red wines, the skins and the juice will be pumped into a stainless steel tank for alcoholic fermentation. The red skins stay on the juice to give the wine its color and flavor.
The rest is history. Well, not exactly, but the rest is for another posting.
If all goes well, I’ll have some pictures of harvest tomorrow.