On learning about Brix: Like every part of winemaking, there are various points at which you must check the Brix (sugar level your grapes are at) in order to make choices about the wine to keep it on a healthy path. I never knew that on the day fruit is crushed or destemmed, its Brix levels do not read accurately due to the new temperature state the fruit is in. It may read too high or too low.
You’ll want to begin taking Brix once a cap is formed. A cap is formed by CO2 forcing grapes to the surface; it is not the same as the “must”. Whenever you take a Brix reading, be sure to use the correct hydrometer for the stage the juice is at. Always record the date, Brix number (with its correction) and the temperature. If a bin is reading at say, 1.3 but is still in the range of 19-21 deg, it’s still warm enough to continue fermentation, as you want that Brix reading to get into the negatives to indicate it’s reaching dry levels.
Once fermentation begins (and you can tell because the grape must gets much drier), the yeast has finished propagating and is feverishly feeding on the sugar.
Note: There are many reasons for selecting a particular yeast strain, but one of them is based on how well it performs during fermentation. You don’t want a yeast strain that overreacts with the varietal so that it works too hard too fast, heats up and kills itself off too early, or worse, releases “off” flavors/aromas that stay with the wine. You want a strain that will allow for a window of fermentation that maximizes sugars to get the juice to the alcohol level you feel best fits that particular varietal and the region it’s grown in (taking into consideration its terroir and how that impacts the ambient yeast already naturally present on the skin of the fruit).
As yeast eats up all the sugar, the Brix levels drop dramatically in a few days. The ideal Brix for wine once the yeast has done its job would be at around -1.0 + (since alcohol is less dense than water and causes this negative reading when the fermentation is complete). The must will be much, much drier due to fermentation and specific gravity. New aromas will come forth as well. Since yeast have nothing else to consume beyond fermentation, as they attempt to survive in search of nourishment, the fruit ends up giving off a skunky, almost-rotten smell which is sulfuric based.
If you’re working with native yeast, this window is less necessary but you’re still checking the fruit’s temperature for some amount of time until the native yeast kicks in. If your Brix stabilizes and fermentation doesn’t start on its own, you will need to take other measures. Some winemakers add water, but I’m not sure at what point that’s done when you’re at the mercy of native yeast. Do you predict a potential stuck fermentation by the way the Brix won’t stabilize and take action by adding water then? I also know that some people work with heat jackets, but I think that’s just for stainless steel tanks, I don’t these jackets are useable with plastic tanks or bins, but I could be wrong. And I don’t think Ed has or chooses to use these devices anyway.
Ed deals with stuck fermentations by predicting them before they actually happen. He looks for the warning signs and adds a significant amount of more yeast. These yeast lees can always be racked off. If he adds water to his bins its only ONCE and to dilute the sugars more so the fermentation is prolonged to the hopeful appropriate time frame. His one-time-only addition to water per bin is based on a particular Brix reading occurring on a particular day.
On learning how to take Brix readings: Today Ed had Taka, our other intern (who has worked about 8 harvests with Ed and flies in from Japan to do so – he also makes his own Pinot at Ed’s facility and sells it in Japan) teach me how to take proper Brix readings the long-hand way: strainer, cup, temperature/hydrometer gauges, graduated cylinder, liter containers and good ol’ math. I loved learning about the process this way as it helped piece together how temperature impacts Brix readings.
To take these readings, Taka had me rinse and alcohol spray all tools and then place the Brix reader hydrometer in one container and the graduated cylinder in another (to keep things clean in case of drips/spills).
We first dipped the strainer into the center of the cap for the best reading (varies on corners of bins). You must press the strainer hard enough into the cap to get enough juice filtering through. Then you take the cup and lap up as much of the foamy bubbles as you can off of the surface of the juice to get a clearer reading. This foam, by the way is the protein. I noticed today as well how the protein foam has a slightly different color, depending on the clone of Pinot. Now you’re ready to fill your cup with the juice and fill to the top of the graduated cylinder. But before you do, be sure to gently set the temperature gauge in the cylinder so it can adjust to the juice’s current temperature and give you an accurate reading for that day’s sample. Never let the containers or cylinder touch the fruit for hygienic purposes but also to avoid any contamination/ruination of the bin should you drop/tip over the cylinder, or worse, break the hydrometer in the juice of the bin itself!
When you’ve filled your cylinder ¾ of the way up, gently drop in the Brix reader. Ed said that Taka is the only person who has not yet broken a gauge. Even Ed admitted to doing so once…eesh! No pressure! It only made me more cautious of course, which is good. The reader will bob a little and so Ed applies the “pull up and spin the reader” in the juice which, I’m guessing, centrifugally-speaking, gives you the more accurate reading. How he figured that out, I’ll never know! Be sure your cylinder is set in the container and on a level surface. A reading is considered appropriate once the spinning/bobbing stops/slows as it might be a little inaccurate beyond that.
Look at your juice’s temperature reading and then consult the Brix/temperature chart to determine the correct Brix reading for that sample. To do this you round off the Brix (so if your reader says 27.1, you round it down to 27) and then look on the chart for the exact degree of temperature and see what the corresponding decimal amount is that you subtract from the Brix. If it’s say, 0.3, your correct reading for that sample if your reader is at 27.1 with a temperature of say 16 deg, would be 26.8. If your reading is an exact number, be sure to add .0 to assure Ed that you didn’t forget to add the decimal portion and the 27.0 was in fact the exact reading.
If you’re taking Brix on a bin that is going dry, your reading will be in the negative range. So if your Brix is -0.8 with a temperature of 19 and a correction of -.01, your reading will be -.07. Vice versa if your reading is still in the positive range (ie; still slightly sweet from remaining sugars), but if your reading was weighing in at 1.3 with a temperature of 19 and a correction of say, for example, + 0.2, your reading would be corrected to 1.6.
Record these numbers on the side of the bin on a Brix sheet in permanent marker so as not to lose track of these recordings. You want to have a good number of readings to determine how well your Brix is stabilizing.
After that, you’re either ready for cleanup or to move to the next bin. To do the latter and avoid making a mess, first pull the reader out of the cylinder and place in the container designated for it. Then, dump the juice in the cylinder back into the bin and place the cylinder back in the container. Then pull the temperature gauge out of the strainer and place in the cylinder. Lift the strainer out and let the juice drain out. Put the cup under the strainer to catch any remaining drips while you transfer the strainer to the next bin.
The cylinder, cup, containers, and sturdier tools like the strainer can all be pre-rinsed and put in the dishwasher. The gauges must be rinsed, taken apart, if applicable, and sprayed with alcohol.