This week marks the passing of a personal milestone: before now, the longest I have ever been away from home was 40 days, and that was when I was traveling in Europe with my family in the summer of 2006. It’s fun to think back to think back to then; I kept a journal while I was there as well, and it’ll be fun to compare it to the one I am keeping now. Reading something like a journal or an autobiography can give you a unique snapshot of a person’s personality. It’s more than just looking at the events that the author chooses to tell about, it’s the way the author tells about them, the word choice, the sentence structure, and the author’s thought process. For me, it’ll be really interesting to have that kind of perspective on my past self.
Here’s an interesting thought: you can do the same thing with a blog. I wonder what inferences you all are making about me (amused at the thought, the author pauses to smile and ponder sagely for a moment. Afterwards, the author goes back to listening to Avril Lavigne and resumes writing). Regardless, I am going to continue writing and posting, if only for the reason that I enjoy telling stories to my friends and loved ones.
And speaking of stories, this week (by comparison to the last few) was pretty eventful. After maybe three consecutive days of absurdly light sample loads (tracking the maturity of our grapes is over since we are harvesting everything, so no more playing with the oversized garlic press), Tina decided to let me go and hang out…errr…help out the “yeasties,” while she took care of the lab. Yeastie is the term used at Mud House, at least amongst the cellar hands, to describe the people who are responsible for daily ferment monitoring, making nutrient or supplement additions to tanks per the winemaker’s orders, and of course, inoculating the tanks with yeast.
I need to back up a bit. For those readers who fully understood the last sentence in that paragraph, you can skip ahead, the rest of you get a crash course in yeast’s role in modern winemaking. Everyone knows that grapes get sweeter as they mature, and that sugar can be turned into delicious alcohol by yeast, the same stuff you add to bread to make it rise. Certain strains of wild yeast live on naturally on the skins of the grapes, and you can use this yeast to make wine yeast (the industry term is “native yeast,” recall me talking about Sarasin in the week 3 entry). However, many modern wineries prefer to use their own yeast to run the ferments, allowing them greater control of their finished wine: while there is no yeast in finished wine, the yeast does contribute flavors and odors to the wine during fermentation, and for that reason only certain yeasts are used to make certain wines. However, wild yeast are still present in the grape juice, so to get rid of the unwanted yeast, you simply add lots of your own yeast, and your own yeast will out-compete the native yeast and any other microbes living in the grape juice.
However, yeast need more than just sugar to live; there are several nutrients vital to yeast’s metabolism that must be present in the grape juice in order for the yeast to be happy, make many little yeast babies, and ferment the sugar. The most important yeast nutrient is nitrogen; if yeast doesn’t have nitrogen available for them to use, they will start using sulfur in the place of nitrogen to metabolize sugar and producing hydrogen sulfide gas. This gas smells like rotten eggs, and is not a desirable aroma in finished wine. So in order to prevent this from happening, a nitrogen source may need to be added to the wine. Even after a nitrogen addition, the wine still may smell a bit eggy (the industry term is “sulfury,” but who cares), and if so, a copper sulfate solution is added in small amounts after the fermentation is over to kill the smell. However, if your yeast are happy, all you need to do is monitor (ie: taste) the fermentation and stop it once the alcohol gets high enough or all of the sugar is gone. There is a lot more to it than that, but that is wine yeast science in a nutshell. Back to the story.
My daily routine changed as a result of my new responsibilities. After calibrating the instruments and running the benchmarks, I would grab a tank sampler, basket, and digital thermometer, and head down to the other lab on the far side of the winery to help with ferment rounds. I would then fill my basket with sample jars and go out into the tank farm to sample all the ferments and take their temperature. At this point there are a little less than 100 separate white ferments going (the red cellar crew takes care of sampling the reds), so thankfully there are three of us. Once all of the tanks had been sampled, we then take the brix, so that when the winemakers taste the ferments they know how far the tank has to go until its completely dry. Mundane? Sure. A terrible job to do in the rain? Oh yes. However, at the moment it’s novel, and breaks up my day nicely.
Once the winemakers taste the ferments, they then decide on what additions to make to which tanks. We then go out and make said additions. Usually if an addition needs to be made, the fermentation has either stopped, or is slowing down prematurely, and the addition is usually meant to kick-start the yeast. Depending on the size of the tank, an addition can be as little as 30 grams of some nutrient, to as much as 10kg for the bigger tanks. Some additions cause the wine to foam, and therefore must be added slowly if the tank is very full. This is a lesson that I learned the hard way:
“I was making a 4kg addition of Superfood (yeast nutrients) and a 4kg addition of DAP to a very full tank (tank 4517) of Pinot Gris. I was in a rush to finish, and…well…volcano happened. They warned me about this, and told me that if it happened to just grab a hose and hose off the tank until it stopped erupting. Well, it happened to be one of those times wen there was no water pressure anywhere in the winery, so I turned on the water hose and nothing happened. All I could do was watch in horror as wine poured out of the top of the tank and spilled down the side…It was my biggest goof to-date at the winery (4-12-11).”
Sadly, I was a little too shocked during this ordeal to grab my camera and snap a picture of my wine-foam geyser. The picture above is actually the result of one of the cellar hands making a mistake, but it very much looks like what I saw on that fateful night. I actually checked the tank the next morning to see how much had been lost to stupidity, and the level had barely changed. The tank erupted for a good five minutes, and I didn’t even scratch the surface! It was the first time I realized how much wine was actually in the tanks.
However, of all of my new responsibilities, I think inoculating tanks is probably the most fun. That is, fun for me, everyone else thinks inoculating sucks because it takes a long time and you smell like a bakery afterwards. I am a very strange chemist: I enjoy running the analysis in the lab as much as the next guy, but I jump at any opportunity to leave the lab and do something, anything, in the winery. Inoculating a tank with yeast requires some manual labor, and a talent for finding all of the fittings and tools you need, two skills that don’t have much of a place in a chemistry lab, but I seem to poses both. Yeast are amazing little buggers, when they are healthy they can really metabolize things quickly. The photo shown is of Miriam, one of the full-time yeasties, bailing off the foam from a very excited yeast culture. She added a little bit of juice to the yeast to give them something to eat and start dividing, and they went completely crazy; we had to grab one of our big drums to store the bailed foam.
Suffice it to say that with all of the scurrying around on catwalks and through the forest of wine tanks, I am spending much more time outside then I used to. I wonder if that is why I enjoy working with the yeasties so much: I get to move around more, and I also get to interact with far more people than I do when I am in lab all day. Maybe part of me is not looking forward to the life of tests and chemicals that I have planned and trained for. Or maybe I am just looking forward to traveling around New Zealand after the job has finished. The jury is still out on the first statement, but what I can say for sure is that I hear more about this country with each passing day, and every day I want to try and cram one more thing to do or see in the extra month I have here. I am seriously contemplating changing my ticket, but I’ll cross that bridge a bit later once the whole graduate school issue has been worked out.
Everyone can tell that harvest is drawing to a close. The trucks are still coming fast and furious (there has been a bit of rain, so the fruit is coming in to prevent rot), but there really aren’t that many blocks left to harvest, according to the viticulturalists. Personally, I am just looking forward to going back to 8 hour days. You don’t realize how much you miss those extra 4 hours every day until they are gone, you can do quite a bit with that chunk of time. We will probably have our last 12 hour shift sometime next week. I can’t wait, but I suppose I’ll have to.
That’s all for now. Take care everybody!
-DK
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