First, a primer. Lees are the spent yeast cells that are the result of fermentation. Once the yeasts have done their thing converting sugar to alcohol, the resulting yeast cells fall to the bottom of the tank, where they are either removed or left behind intentionally. If they are left behind, it’s because the winemaker wants what they’ve got – the ability to “self-destruct.” In doing so, the yeast cells produce amino acids and release proteins and carbohydrates into the wine. This process, called autolysis, results in a creamy mouthfeel in the wine along with bready, yeasty (naturally), biscuity, brioche-like, and even toasty aromas and flavors.

So why do it? Texture is the main reason. Take, for example, nonfat milk versus whole milk. Nonfat milk is a relatively thin, almost watery liquid that goes right down the hatch without much mouthfeel, so to speak. Whole milk doesn’t just taste richer, it also creates a lingering mouthfeel. A lees-aged wine will never be palate-coating like whole milk (hopefully!), but it does create a fullness in the mouth that is not only inherently satisfying but, and here’s the bonus, it broadens its food pairing possibilities considerably. We’ll get into that a little further down.

There are other good reasons for aging wine on the lees. The proteins released by the yeast cells help soften the acidity in the wine. Even though Verdejo is more of a medium-high acid grape and therefore not necessarily in need of a reduction in acidity, it’s a means of creating a different style of Verdejo, one that’s richer and yet still has plenty of acid to balance it. In addition, the enzymatic action generated by the dead yeast cells increases the wine’s ageability because it reduces oxidation in the wine.

Lees-aging will also preserve and enhance fruit aromas and flavors in the wine. These may be fresh fruit characteristics, or they might be cooked or canned fruit. Whatever the case, what’s certain is that the very best lees aging technique coaxes out the full expression of the Verdejo grape while maintaining the qualities unique to the grape and the acidity that keeps it fresh.

One more advantage to lees aging is that, by definition, a wine that is aged that way is almost always going to be released older than one that is not. That can mean months or even longer depending on the aim of the winemaker. A longer-aged wine doesn’t automatically mean a better wine, but it does mean one that’s more complex and theoretically, of somewhat higher quality.

Not every Verdejo is made using this process. If a winemaker is looking to create a fresh, ready-to-drink wine, then he or she will ferment the juice, let it settle, and then bottle and sell it a few months after harvest. This style of Verdejo is crisp, juicy, and just about perfect as an everyday wine.

Lees and oak together

Sometimes a winemaker will decide to age their Verdejo not only on the lees but also in oak. Because oak is porous, it will automatically enhance the texture of the wine. Together with the lees, it’s a given that the wine will have a fuller mouthfeel.

Lees aging in oak also does something else. If the oak is new (versus neutral or used oak), then it will not only lend spice characteristics and enhance the fruit aromas in the wine, it will also bring out a level of toastiness. Combined with the same characteristic derived from autolysis, it’s sometimes hard to tease apart its origin. In the end, if that’s a quality you like, then where it came from doesn’t matter. But like all such techniques, the extent to which they’re used is a matter of taste.

This begs the question: does lees aging combined with oak impart too much of a good thing? According to Jordi Paronella, Wine Director for the José Andrés Group, it can actually enhance a wine. However, he urges restraint, “I don’t think barrel aging on the lees takes away from the variety. If done properly, it makes sense.”

There’s also the matter of money. The longer a wine stays in the winery, the longer it goes unsold. For a winemaker, that is one of the many decisions he or she must make when deciding the style of wine they’re looking to craft. However, it’s pretty much a given that the more the steps between harvest and market, the more complex the wine and usually the higher the price.

Rueda Verdejo is rare among white varietals because much of it comes from old vines – some older than a century. Old vine wines are usually more concentrated because the grapes that grow on them tend to be smaller and fewer, so the grapes that do grow have greater intensity. For this reason, the wines made with these grapes including Verdejo can be made successfully in a variety of ways including lees-aging and/or oak. For more on old vine Verdejo, check out our article on Gran Vino de Rueda, the Rueda DO’s newest designation.

Cement eggs

Many Verdejo producers use cement eggs instead of stainless steel to ferment and sometimes age their wine. Unlike oak, cement won’t impart flavor, and unlike stainless steel, it allows a wine to breathe ever so much. Also, the egg shape combined with the heat from fermentation fosters movement of the wine inside while the shape of the vessel results in the lees dropping to the pointed end of the tank. Even though the yeast cells fall, the movement of the wine moves those lees around, creating a sort of natural stirring or bâtonnage as it’s called in French. It’s a sure bet that the wine made in this  tank style will emerge with more mouthfeel than one made in traditional stainless unless lees aging and bâtonnage are employed there.

So why would a winemaker ever use stainless steel if they can achieve greater complexity by using cement or oak? Again, it comes down to the desired style. Wine made in stainless is, by definition, reductive winemaking – wine made without oxygen. This is done so that the wine maintains freshness, fruitiness, and acidity – characteristics that are exactly what a young Verdejo brings to the table and, for that matter, the reason it’s on so many tables in Spain and beyond. It didn’t get to be Spain’s number one selling white wine for nothing.

Wine Director Paronella prefers Verdejo in this younger style. He especially likes it when vegetal characteristics like fennel, asparagus, green tomato leaf, and wet stone dominate, though other characteristics like citrus and tropical fruit are also common in Verdejo. He likened his preferred style to Sauvignon Blanc from the Loire Valley of France.

When the wine displays these characteristics, Paronella looks to the ground for pairing options, “Whatever comes from the earth – mushrooms, brussels sprouts, asparagus, eggplant,” he said. When the wine has been lees-aged, whether in oak or not, he’ll consider grilling the vegetables or topping them with butter.

Master Sommelier and author of the book, “Message in the Bottle: A Guide to Tasting Wine,” Tim Gaiser agrees. But he takes it one step further. “Verdejo,” he says, “is like a chameleon depending on what you’re having with it. It matches a lot of different styles of food. The fact it’s not heavy and the fact it has the acidity it does, it works with a lot of things.”

One thing is clear. Verdejo is an exceptionally versatile grape. That versatility begins in the vineyard, where it may be grown on newly planted vines or on decades-old ones. It may be made in stainless steel and bottled soon thereafter to make the ultimate porch pounder, or it may be made in a cement egg for a fuller-textured wine that may or may not have extended lees contact. Or it may be placed in neutral oak not only for texture but also to enhance the brioche and yeasty characteristics that naturally occur from that method. If the oak is new, then sweet caramel-like and/or vanilla notes along with baking spices will likely emerge as well.

The next time you see a bottle of Rueda Verdejo with a label sporting the words “sobre lías” or lees-aged, you’ll know it’s not just a marketing gimmick. It’s the result of a serious winemaking decision that happened long before that label was affixed to the bottle. It’s one that means a whole lot of time and care went into the making of that wine, and it’s one that urges you to slow down when you sip it. Time and texture matter, but no more so than with this prized white grape of Spain.