Yeast are very complex little creatures. They're a single celled fungus, and the type that is primarily responsible for alcoholic fermentation is called saccharomyces cerevisiea. The inner workings of a yeast cell are much like those of our own cells, with similar internal structures that have great names like mitochondria, golgi bodies, and endoplasmic reticula. They really aren't that different than we are on a cellular level. The major differences are the way in which they get energy from their food source, and what they produce as a result. In a very basic sense, fermentation is how yeast get energy to live.
As important as grapes are themselves in wine aroma, the bulk of the aromas in wine arise through the fermentation process, that is to say, yeast take what is present in the grapes and convert it into aroma and flavor.
The major aromatic compounds that come from yeast action are organic acids, higher alcohols, esters and aldehydes. As yeasts go about the business of producing alcohol, it's not a linear process of sugar in alcohol out-- there are a number of steps that the sugar goes through and at each step an intermediary is produced. Some of these go on to become aroma compounds rather than alcohol. In addition, sometimes the alcohol reacts with one of the intermediary products to form an aroma compound. It's all part of a living system, and living systems tend to be pretty complex.
The major compounds that yeast are resposible in wine are volatile fatty acids, higher alcohols, esters, and sulfur compounds. With many of these compounds, the effect of their presence can be either pleasant or unpleasant depending quite a bit upon their concentration in the wine.
Volatile fatty acids include compounds like acetic acid, which is essentially vinegar, and octanoic acid, which can taste sweet and buttery, and they are the products of two enzyme systems in yeast. They can range from oily to rancid to sweet and back again.
Higher alcohols are formed through the interaction of amino acids and sugars, and can account for such aromas as marzipan, fresh grass, and flowers.
You may remember from our discussion on grapes that esters are responsible for general fruity aromas in wine. Yeast produce these through sugar byproducts-- from a reaction between alcohol and a compound called acetyl-CoA, or through an interaction between amino acids and alcohol. They can give the wine aromas like banana, violet, and pear.
Unfortunately, yeast also can produce sulfur compounds that can add an unsavory note to wine. If you've ever had a wine that smelled like rotten eggs, burnt ruber, onion, or boiled cabbage, you know what I'm talking about. Those are yeast-produced aromas, and they're all sulfur compounds. Luckily, properly managing the fermentation process can ensure that yeast don't produce these in levels that are detectable.
This is obviously a very compressed version of how yeast contribute to the aromas in your glass of wine, but barring getting too deeply into metabolism, I hope it has helped illuminate the important role that yeast have to play not only in producing the alcohol in wine, but in the development of the aroma and flavor itself.
We're finally coming to the close of our bottling season. Whew.
If you've been into our tasting rooms, hopefully you've gotten a taste of our recently released 2015 Cabernet Sauvignon, 2016 Sauvignon Blanc, and 2016 Rose. Allow me to give you a sneak peek of some of our upcoming releases...
2015 Viognier (Coming to a tasting room near you this Friday!)
2014 Petite Verdot
And stay tuned for more...
It's going to be a great summer!
Everyone would like to think that their wine is fermented grapes and fermented grapes only, but I'm here to break it to you: that's almost never the case. Luckily, I'm also here to elucidate what might have been added to the wine you drink and most importantly, why.
Which brings me to an ingredient that I am very passionate about. Sulfur.
More specifically, sulfur in the form of sulfur dioxide. Good old SO2.
SO2 is one of my favorite winemaking ingredients, because it serves a dual purpose in a wine solution. It is antioxidative, and it also inhibits the growth of microorganisms.
As an antioxidant, it works to block oxidative reations-- that is, the sorts of reactions that make your wine start to smell and taste like spoiled fruit.
As an antimicrobial, it helps prevent the growth of bacteria, molds, and yeasts that can grow in wine and turn it into vinegar, or otherwise spoil it.
It's true that SO2 can be toxic when ingested in high doses-- the number isn't exactly set in stone, because doctors don't want to kill people to find out where that threshold is. They think it's somewhere around 190 milligrams per kilogram of weight (or about 86 milligrams per pound). An acceptable daily intake is considered to be about 48 milligrams per day for a 150 pound person. To put this in perspective somewhat, your body produces about 2,000 milligrams of sulfur dioxide just on its own every day, and that's also about how much you urinate out.
How much SO2 we add to a wine depends on its pH (the concentration of hydrogen ions in solution), but as a general rule of thumb, we target about 35 milligrams per liter of wine. This works out to about 26 milligrams per bottle. So unless you're drinking a bottle of wine and more per day, you're probably not in a lot of danger of overdosing on SO2. And in all seriousness, please don't drink that much wine. Share some with a friend, or cork it up for the next day.
And to add another layer of perspective on SO2, it's in quite a lot of food products. Dried apricots can contain nearly 2000 milligrams per kilogram, and they're the reason that dried apricots are still a vibrant orange color, rather than a dark brown-- that's an antioxidation example for you. It's in sugar, salad dressing, bottled fruit juices. Mostly things that you want to consume in moderation anyway.
We add sulfur here in the form of potassium metabisulfite, or KMBS for short. In water, the potassium disassociates and you get an active form of sulfur. It's a powder, and we dissolve it in a small volume of hot water before mixing it into wine. Larger wineries might keep a tank of pressurized liquid SO2 on site, which can be released directly into wine in tank. For our purposes and size, KMBS makes the most sense for us. And we take into account the alcohol level and the pH of the wine to make sure that we're only ever adding the minimal amount necessary to be effective against microbes and oxidation.
I hope this has shed a little light onto sulfur use in the winery. If you've heard about some other ingredient in wine that you'd like me to talk a bit about, please feel free to comment and let me know. I'm open and taking suggestions.
Most of us have eaten a grape-- usually a table grape from the grocery store. If you're lucky enough to have visited a vineyard or an enterprising tasting room around harvest, you may have even had the chance to taste a wine grape. Neither of these experiences, however, really elucidates much as to how a wine made from the same grape will actually smell and taste. If an alien came to earth and was given each, I doubt it would deduce that one was derived from the other. Why is this?
First of all, let's talk grape berry structure. The three main components of a grape are its skin, its pulp, and its seeds. Different compounds are found at different concentrations in each of these parts of the grape.
What even is a grape made of? Seventy-five to eighty-five percent of a grape is water. Fifteen to twenty-five percent is sugar. Acid makes up half to one percent, and pectin accounts for about a quarter of a percent. Add these numbers up, and you have very little left to work with in order to distinguish one type of grape from another. Luckily, the compounds that account for the vast differences in the wines made from these grapes require very small concentrations for the human nose to detect them once they are released from their bound forms.
These aroma and flavor compounds fall into a camp known as secondary metabolites. These largest group of these are phenolic compounds. Phenolics are a diverse group, including tannins, which contribute structure and mouthfeel, anthocyanins, which give wine its color, and flavonols, which work in concert with tannins and anthocyanins to boost their effects. These are generally found in all parts of the berry. The role these compounds play in terms of flavor is that they are responsible for the bitterness and astringency of a wine. In total, these make up about 0.65% of a grape.
And finally, the really fun stuff-- the compounds that really differentiate one grape variety from another...
Terpenes are responsible for floral aromas in wines, most notably in Muscat varieties and their cousins. They have fancy names such as geraniol (which smells like geraniums), and linalool (which smells like roses). It doesn’t take a very high concentration of these compounds to tickle your nose. In fact, many ripe grape aromas are dominated by terpenes. They come in two forms-- free, which is just like it sounds, and-- glycosylated, which is a fancy way of saying "attached to a sugar molecule." When attached to a sugar, they don't have an aroma. When free, they do.
Pyrazines are the compounds culprits for vegetable-like aromas in wine, and their detection thresholds tend to be very low. They can be a good thing, such as in herbaceous New Zealand-style Sauvignon Blanc, or a bad thing, such as in Cabernet Sauvignon, which if picked too early, can be overwhelmed by green bell pepper odors.
Volatile esters tend to be accountable for the various fruity aromas you get when sticking your nose in the glass. They can smell like specific fruits like strawberries, peaches or even bananas, or can just contribute to a generally “fruity” bouquet.
Thiols are sulfur-based compounds that span a huge range of aromas from cooked cabbage and garlic to passionfruit and grapefruit. As you can imagine, they can be either a pleasant or unpleasant addition to the drinking experience.
Norisoprenoids are compounds that are derived from carotenoids, which play a part in photosynthesis. The two best known compounds in wine that are associated with this class are beta-damascenone, which is the primary aroma in roses, and also present in fruits like raspberries, and TDN, a diesel-type aroma, which is not a norisoprenoid per se, but tends to increase as carotenoids break down.
So now that I’ve overwhelmed you with wine science, why don’t you go fill a glass with your preferred alcoholic blend of esters and monoterpenes, with judicious splashes of pyrazines and thiols. I’ll meet you back here in a few weeks to talk through the role of yeast in wine aroma and flavor.
Situated where we are, we tend to get a variety of interesting wildlife passing through the winery grounds.
This past harvest, a baby hawk hatched on the roof of the winery, and learned how to fly behind the building. This is a photo of its first day out testing its wings. It spent quite a while hanging out and watching us put grapes through the destemmer and crusher.
It's starting to warm up outside, and in my home that means the number of white wines in the refrigerator climbs exponentially. While Scott and Dan may be dyed in the wool Chardonnay fans, my personal tastes skew leaner and brighter, putting Sauvignon Blanc right in my wheelhouse. It's a grape that can quite often be polarizing-- whether in its flinty, gunsmoke and grass form from the upper Loire, France, or its extravagently tropical passionfruit and gooseberry form from Marlborough, New Zealand. Some people are wild about it, and some just won't have it.
You may remember a few posts back when we talked about aroma compounds-- well, this is a grape whose aroma is very driven by thiols, the compounds that are responsible for green, herbaceous notes.
The grape itself most likely originated in the Loire Valley, perhaps around the towns of Sancerre and Pouilly-- so far up the Loire River that they're actually closer to Chablis than to the other major wine-producing regions along the river. It is likely the offspring of the grape Savagnin, a grape which also gave us the grapes Chenin Blanc, Gruner Veltliner, Petit Manseng, and Verdelho.
From the Loire, Sauvignon Blanc spread to Bordeaux, where it makes up substantial parts of the white blends of the region, and where it hooked up with Cabernet Franc to produce perhaps the most famous wine grape in the world - Cabernet Sauvignon.
And, of course, it has since claimed space in most of the major wine regions in the world-- including here in Arizona and neighboring New Mexico, which is where our 2016 Sauvignon Blanc originates from. It is the thrid most planted white variety in France, and is also planted extensively in California, Chile, Australia, and (of course) New Zealand. It tends to do best in cooler climates, as it can yield a rather boring wine if it overripens.
To try to coax out a wide variety of aromas and flavors from the fruit we received, we brought in an earlier pick and a later pick. We were hoping to capture some of the greener compounds from the early fruit, and some of the tropical notes from a later pick. We then fermented with a blend of wild and cultured yeasts all targeted towards developing Sauvignon Blanc aromas and flavors. We also fermented as cold as possible to retain as many volatile thiols as we could. I'm very pleased with our efforts, and if you happen to be in the area, please stop by the Scottsdale Tasting Room and give this recent release a try. If you like the wine, let us know! We'd love to hear your feedback.
A few weekends ago we held our first annual Valentine’s Winemaker Dinner at the Scottsdale Tasting room. It was a real treat for me to get the opportunity to meet some of our wine club members who have been with us from the beginning, and to once again see those whom I’d met here in Willcox. It’s such a pleasure to hear the stories that everyone brings to the table, from tales of the family’s pet tortoise to a couple first getting together following a wake… everyone’s life is different and interesting, and I’m grateful that wine and food can bring us together at the same table to share with one another.
Over a dessert of crème brulee, we popped open a few unreleased bottles of the sparkling Malvasia Bianca that we made this past harvest, and I spoke a bit about the wine—specifically how much I enjoy its peach and slightly bitter grapefruit aromas and flavors. One of my fellow diners exclaimed over the grapefruit bitterness, and asked if we’d actually included grapefruit in the fermentation. This is a pretty logical question, and I’ve been asked more than once some sort of variation on it.
While there are some wines that are made with an addition of some other fruit juice, most of the wines you encounter at your local liquor store, supermarket, or restaurant do not. And yet, they’re nearly all accompanied by a tasting note evoking a veritable fruit salad. They’re just grapes, you might think. How is it possible for this glorified grape juice to taste like all these wacky things?
In the laboratory, there have been over 1,000 different aromatic compounds isolated from wine and these all come from just a few sources: the grapes, the yeast, the malolactic bacteria, and the oak, if it was used. Stay tuned-- once a month, I'll break down one of these components, and talk about what it contriubtes to the aromas and flavors of wine. Hopefully by the end of this, you'll have a better understanding of what's going on to make a wine smell and taste like it does, and I'll have reminded myself of all the stuff that slipped out of my brain since school and all the bottles of wine Ive drunk since then. I hope this will be a fun journey for all of us.
Last month, we had a tour come through the facility with Wings over Willcox, and once we hit the bottling line, it was the first thing asked.
I like both screwcaps and corks. Here at Aridus, we have the capability to either cork or screwcap, which is nice, but really—why do we choose one over the other?
The short answer is this: we use screwcaps for wines we expect that you’ll drink right away, and corks for those that we hope you’ll lay down and age for a little bit before breaking into them.
In reality, it’s a little more nuanced than that. There are a number of factors that we take into consideration when deciding on a cork or a screwcap. The first of which is type of wine. When you choose a screwcap over a cork, one consideration is that you’ve suddenly got a lot more headspace in the bottle. During bottling, the bottle is evacuated and the air replaced with nitrogen prior to filling, which minimizes the amount of oxygen present in the bottle, but it is still a larger volume of gas in bottle than with a cork.
With that in mind, it’s also important to consider when the bottle is going to be drunk. Is it tonight? In two weeks? Or maybe in ten years? The shorter a time span between when a wine is purchased and when it is drunk, the more a screwcap makes sense.
Besides, how easy is it to use a screwcap? It’s just downright fun— one twist, that delightful cracking sound, the give of the cap in your hand, and it’s instant party. As Scott likes to say, easy breezy. They can be downright gorgeous, too. I can get lost for hours browsing the Mala closures website.
A cork seems to lend itself to situations with a bit more gravitas. You cut through the foil, then twist the spiraled helix into the pliant center of the cork. Brace the arm on the lip of the bottle and pray a little bit as you lever the cork out the bottle’s neck. Phew, it didn’t crumble or crack. Yes, corks are definitely for wines that want you to muster your skills and bring all your attention to hand.
There's also a price difference. A screwcap costs 25 cents, whereas a cork and a foil cost 60 cents. That may not sound like much, but when you think about something like the Sauvignon Blanc that we recently bottled, totaling 6000 bottles, it’s a difference of over $2100. (We corked that one.)
At the end of the day, we’re always going to aim to deliver a quality bottle of wine. And only your own rules apply once it’s in your own home. But if this little post helps you out at all by giving you some insight into our decision-making, that’s all that really matters.
As a winemaker, one of the questions that I’m asked frequently is, “What is your favorite wine?”
As with all simple questions, there’s not a simple answer. At least not for me. But nobody wants to hear, “Well, it depends…” And I completely agree! It’s a cop-out of an answer. The reality of it is that I’d GLADLY spend the next hour telling the inquirer about all the wines that I love, for what reasons, at which occasions, and so on. But I’m also self-aware enough to realize that in the moment, a short answer is probably best, so in my attempts to be truthful—to say that I have many favorites—I wind up sounding wishy-washy.
Once a month or so, I’m going to take the opportunity to tell you about one of my favorite wines, in as much detail as I can, because in a blog format, you can opt out the moment I start boring you. Or come back after you’ve filled up your glass. I’ll be none the wiser, whatever you choose to do.
Without further ado: Graciano.
Variously known as Tinta Miuda in Portugal, Bovale Sardo in Sardinia, and Morrastel in France’s Languedoc, this grape originates in Spain, where it is perhaps best known for its supporting role in some of Rioja’s longest-lived and most perfumed wines. The vine itself is drought resistant, which makes it a good fit for Arizona’s climate. Because we’re so dry during most of the growing season, its susceptibility to rot and mildew is mitigated.
In 2016, we fermented out three different lots of Graciano. I was always in a good mood when it came to punching them down, too. They were all remarkable in their deep purple color, which seemingly developed overnight. And they were all completely different from one another. Our first lot smelled and tasted of black cherries and beef jerky. The second was slightly lighter and intensely floral. When the final lot came in, the entire winery smelled like black pepper, which carried through into the final wine. Not only that, but the last lot finished malolactic fermentation prior to the others, despite having been brought in nearly a month later.
I’m excited to blend all these once they’ve all had plenty of time to mature in barrel. Like certain other varieties I know ahem (Petite Sirah) ahem, our Graciano has been wildly moody swinging from funky to flat to expressive and back again. I have great hopes for this surprising variety.