This is part 4 of the From Plant to Bottle series. If you are just joining me, you may want to start from the beginning of this series.
OK, so we have finally gotten to the exciting part…harvest! Assuming we have met all of the parameters we have been looking for…good pH, acid, sugar, ripeness of grapes and seeds, and, of course, they taste good, it is time to get those pickers out and working – unless, of course, a mechanical harvester is being used. If you have never seen one of these machines in action, you should try to visit a local winery the next time they fire theirs up. They are quite fascinating.
Picking grapes goes anywhere from the ridiculous to the sublime. If you are a Sauterne grape in France, chances are you will be harvested individually – in other words, one grape (not bunch) at a time. Grapes are picked several times and only the ones that meet the criteria of the winemaker are harvested at a given time. Sauterne is an exquisitely sweet dessert wine (not to be confused with anything labeled sauterne in the United States) and, as you can imagine, extremely expensive…as much as over $200.00 a bottle. More common is hand picking by the bunch which is always done by premium wineries as this keeps the fruit intact and is very gentle. Hand picking keeps the juice from running and turning brown or oxidizing. Machine harvesting is used by many of the wineries that have a large volume of vineyards and is very quick, as you might imagine. But the terrain must be fairly level or barely sloping to run such a machine. It does manhandle the grapes quite a bit, although there are ways to mitigate these problems. The grapes can be harvested quickly, very early in the morning (actually night for me and probably you) while they are cool, and, if they are processed immediately, there is little damage, if any, done.
We would like our pH to be somewhere between 3.2 and 3.6, with closer to 3.2 more desirable. When the pH is on the lower side, the wine is less susceptible to spoilage organisms that are often air-born no matter what you do. In addition, you will be able to add less of the anti-oxidant, metabisulfite (also known just as sulfite), which is a good thing for many reasons that I will discuss later. The level of acid one is looking for can be dependent on the style of wine that is being made. For a white wine that should be fresh and fruity, e.g. Riesling or Chenin Blanc, I would be looking for acid levels of .70 to .90, as tested by pH meter and chemicals to be mentioned later. For a red wine or a white, such as Chardonnay, that I plan to put through malo-lactic fermentation and would like to have end up very soft with full body, I would be looking for acid levels in the range of .60 to .75. Of course, as I previously mentioned, the sugar content or brix should be, for the most part, 21 brix or higher in order to have the proper amount of alcohol in the finished wine. I know that I am using several terms here that may be unfamiliar but I plan to explain them as we get to that stage of the winemaking process where they apply.
Having said all of the above, the truth is that there are many obstacles in the way of achieving the most balanced ripe grapes to harvest. Mother Nature playing games is number one followed by grape variety and climate/growing conditions in your part of the country. While it may be quite easy for growers to meet these parameters most of the time in places such as California due to their lack of rain and plentiful sunshine, it is indeed difficult in many parts of the country, but these problems are not insurmountable. If it rains during or near harvest, the grapes take up the water and sugars and acids go down and flavors become weak. Some years, cold weather comes early and stops the sugar levels from increasing, and so, while you may have some reasonably ripe fruit that tastes good, you are not going to get any more sugar. Should it become warm and dry again, grapes will give back the water, and the sugar and acid levels will climb again. This is what we hope for but some years it simply does not happen.
What to do, what to do!! This is not a hopeless situation. There is no reason why you cannot add sugar to the crushed grapes (also known as must), and a great many commercial wineries do. Certainly I have done it many times over my 35 years of winemaking, both amateur and professional. In fact, some grape species never reach 21 brix and must always have sugar added. Here are a couple new words for your vocabulary lesson: chaptalization and amelioration. Chaptalization is adding just sugar to your must. Amelioration is adding sugar mixed with water to your must. Now go ahead and impress someone by using one of those in a sentence today. Hopefully, you will be talking about winemaking when you do so.