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Fermentation 411: Concrete, Oak and Steel, Oh My!

Fermentation 411 Ryan Render Rendarrio Vineyards

There’s just way too much to know about wine! We could go on for ages just talking about where to store it, how it’s harvested, and (of course) what to pair it with. Alas, we wine nerds love the unknowable nature of the humble wine grape. That’s why, today, we’re delving into some totally brainy territory. That is to say: “How does oak, concrete, or steel fermentation vessels transform what we taste in the glass? Sounds like a complicated question, but we promise you it’s not. We even have “Professor” Ryan Render, winemaker/owner at Rendarrio Vineyards to help with the specifics. You’ll do great. You always were teacher’s pet!

From Juice to Alcohol

First things first: Every wine undergoes fermentation, the process that turns fresh grape juice into the beginnings of a delicious alcoholic beverage. In technical terms, fermentation is a metabolic process that converts sugar to alcohol (and boy is it fun to watch those bubbles fermentationappear in the tank). You probably already know this (gold stars for you). However did know that there are often not one but two fermentation processes in some of your favorite wines? Fermentation isn’t a one-size-fits-all process by any means. Your wine might be first fermented in one vessel (say, steel) for bright clarity then fermented a second time in a specific variety of oak, adding just a touch of toastiness on the nose. After that, the wine can be aged in a multitude of materials, adding (or subtracting) from the wine’s overall flavor. Whether you prefer minimalistic wines or a heavy oaky finish, you’ll want to know the what, when, where,and why of fermentation. Trust us.

Ryan Render Rendarrio Vineyards thumbProfessor Render says: “Whether or not a winemaker chooses one type of fermentation vessel over another really comes down to their specific winemaking philosophy.”

Extra Credit: Head out to Rendarrio Vineyards this fall and ask all the questions you desire. Check out the newly expanded tasting room, reserve tastings, and harvest events.

Mapping and Directions:

Oak: A Classic Take

You know oak—it’s one of the most familiar wine descriptors out there, and there’s a reason for that. You can taste it when you sip a big, flavorful Cabernet Sauvignon or a classic Chardonnay that’s seen an oak fermentation or aging process. That’s because oak offers up savory counterpoints to the fruit at hand (this is why
oak is often described as nutty or caramel-esque). Oak may be a common method for both fermentation and aging, but not all oak tastes the same. French oak often produces a stronger floral scent and rich, vanilla flavor, while Hungarian oak offers up a more neutral experience that lets the fruit stand more on its own. Different wood types also boast varying pore sizes, which can impart more or less tannic structure into a particular fermenting wine. If you were to look under a microscope, you’d see that American oak has a higher density and more carbohydrates, which can create sweet, spicy or nutmeg flavors. Moral of the story: Don’t stop at simply “oak.” Always ask, “What kind?” and “why?”

Professor Render says: “A lot of winemakers have gone back to oak Four Lanterns Buy the Winefermentation for red wines to soften the tannins and create more color and stability.”

Extra Credit: Four Lanterns 2014 Firelight Syrah: Can you taste the savory, oaky nose on this luscious red, described by Wine Enthusiast as boasting “strong pepper notes, elderberries, sesame, and smoked meat?”

Mapping and Directions:

To Ferment in Cement?

Ever heard of a cement egg? No? You’re not alone. However, it is true that the trend toward using large, concrete spheres is soaring in popularity again. Why ferment in cement? Well, the material remains cool, and maintains a very consistent temperature. This is great news for delicate whites like Sauvignon Blanc and Viognier that are often picked during the
coolest hours of the day to maintain balance within the fruit. Concrete is also porous, and unlike stainless steel (which does not allow for micro-oxidization) wine that is fermented in cement eggs receive just the right amount of air while transforming from juice to alcohol. The coolest part, according to many winemakers lies in the egg’s ability to get “out of the way” of Mother Nature. Depending on tSculpterra Buy the Winehe wine grape, you may taste more of the fruit’s natural flavor—and, as a result—get closer to the vineyard it once called home.

Extra Credit: 2014 Sculpterra Sauvignon Blanc: Can you taste how this refreshing white holds nothing back when it comes to its citrus, melon, and honeydew fruit appeal?

Mapping and Directions:


Stainless Steel: Not Just for Appliances

Stainless steel tanks aren’t just flashy and beautiful on the crush pad: they’re also incredibly useful workhorses that allow many winemakers to keep fermentation neutral. Greater control over the flavors imparted during fermentation = more fun when it comes to aging. That means fresh fruit flavors shine without added distraction, creating a truly clean slate. Many modern Chardonnay producers, for example, are turning away from oak fermentation to stainless steel fermentation, making for a truly crisp, bright wine uSextant buy the winenmatched in its refreshing drinkability.

Extra Credit: 2014 Sextant CC Chardonnay: Sip this fresh, citrusy Chardonnay and experience why it was fermented din 90 percent stainless steel. Can you taste the two vineyards used—Monterey County and Edna Valley?

Mapping and Directions to Paso Robles tasting room:
Mapping and Directions to SLO tasting room:



This blog was written by Hayley Thomas, food and wine writer for SLO New Times and You can reach her at [email protected] or follow her on instagram @flavorslo.

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