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.
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