Ever Wonder? How Does Temperature Affect Wine Fermentation

There’s a lot of chemistry that goes into making wine. And we learn from basic chemistry that heat is a catalyst. When heat is applied to a chemical reaction, it speeds things up. So, temperature plays a role in the fermentation of wine.

The higher the fermentation temperature the faster the yeast will convert the grape’s natural sugars to alcohol. But, winemaking is a slow process. From the growing of the grapes to the aging of the wine. And, fermentation is no exception. Winemakers don’t want to rush this process. So, they actually take steps to cool-down, the thus slow-down, the fermentation process.

If a wine is fermented at too high a temperature, it can lack character as well as remove any terroir that the winemaker was hoping to capture. By fermenting a lower temperatures, a winemaker preserves the fruit flavors and helps preserve the subtle elements that terroir can add.

Red wines are typically fermented between 70 and 85 degrees F (20-30 degrees C). This temperature range results is richer colors, good tannin levels and richer fruit flavors. Fermentation temperatures that approach 90 degrees F can result in “cooked” flavors making the wine taste stewed, prune-like or raisin-y.

White wines are typically fermented even cooler than red wines at temperatures between 45 and 60 degrees F (7-16 degrees C). This helps preserve a white wine’s bright fruit aromas and flavors while providing balanced acidity levels.

Why Three Bottles of California Merlot Can Taste So Different

I just had the opportunity blind taste three bottles of California red wine. To start the blind tasting, I did not know the varietal type but was told it was a single varietal wine. And, I was informed that one bottle was from the California Central Coast, one was from Paso Robles and the other was from Napa. It turned out that they were all California Merlot. But, each of the three bottles tasted very different. So, why is this?

One simple answer is - Terroir (p. Te-war). This is a French word that’s derived from their word for earth which is “terre.” It describes the interaction of soil, climate, terrain and grape variety in a specific site, and how they each imprint the wine, making each wine from a specific site distinct.

Here’s an overview of the various components that define a terroir:

Varietal Type

There are multiple types of Merlot grapes, often referred to as various clones. And a quick survey says there 12 certified clones of Merlot in France, approximately 30 registered clones in California and hundreds of clones of Merlot throughout the world. So, there is great variety within the Merlot family of grapes.

Soil

Throughout the world, there is tremendous differences in the types of soil, rock and minerals. Soil definitely affects the flavor of wine while the jury is still out on the topic of rocks and minerals affecting a grape’s flavor. But, many believe that minerals play a defining role.

Terrain

The geological features of a wine-growing region (e.g., mountains, valleys) as well as surrounding plants and large bodies of water (e.g., rivers, lakes and oceans) affect how a wine tastes.

Climate

Wine regions can vary significantly in climate from cool and foggy to hot and sunny. Warmer climates typically generate higher sugar levels whereas cooler climate wine grapes generally have lower sugar levels and higher acidity.

Other Factors

There are also a host of different winemaking techniques that affect how a wine tastes. We’ll get into those next. Until then, Cheers!

How Vegan Wine is Made

Last time we learned that wine makers use clarifying agents in the ‘fining’ process to remove small natural particles that exist in wines. These particles includes microscopic protein particles from grape skins, seeds and dead yeast. And, the most common agents used in clarify or fining a wine are gelatin (an animal protein), albumin (egg whites), casein (animal milk protein) and isinglass (fish bladder). While these agents do a very good job of clinging to particles and then being removed from the wine, they disqualify a wine from being considered vegan.

So, what does someone who is a vegan do? Well, as the market for vegan wines grows, wine makers are learning to make wines without the use of animal products.

Wine makers can choose to either leave the particles in the tank or barrel and allow them to sink naturally to the bottom (a slower, more costly, but completely natural method), or use non-animal based fining products.

Today many winemakers use clay-based fining agents such as betonite, an unusual form of clay, or carbon (activated charcoal). There is even a man-made plastic substance called poly vinyl poly pyrrolidone (PVPP) that is an effective synthetic water-soluble polymer fining agent. There are even vegetable-based gelatins, and other protein fining agents that are being derived from peas and potatoes.

So, vegans, don’t despair. There are wine makers looking out for you. Now, you need to look out for them. Check the label. If it’s vegan, they want you to know and will prominently feature it on the label. Cheers!

The Four Styles of Valpolicella Wine

Valpolicella (val-polla-chellah) is an Italian wine region that covers 95 square miles across the western part of the Veneto region.

There are four primary styles of Valpolicella. In the order from least to most intensity they are: Valpolicella, Valpolicella Ripasso, Amarone della Valpolicella and Recioto della Valpolicella. These wines are all made with the same grapes (Corvina, Corvinone, Rondinella and Molinara) but the wine-making techniques is what differentiates them.

So, here’s a brief overview of each style.

Valpolicella - This wine is fresh and fruity and the lightest style. It typically has bright aromas and sour cherry flavor that is so typical of many northern Italian red wines. It should be slightly chilled and enjoyed with lighter fare or simply as a refreshing fruity wine on a warm afternoon. Wines labelled as Valpolicella Classico come from the original Valpolicella zone. To be labelled as Valpolicella Superiore, the wine must be aged a minimum of one year in wood and have a minimum alcohol level of 12%

Ripasso - This style is just a bigger version of Valpolicella. It gains it added flavor because it is produced using the Ripasso method of wine making. It starts with the basics used in making the Valpolicella wine, but adds a second fermentation that takes advantage of the pomace - the leftover grape skins that remain after the grapes are pressed for the Amarone and Recioto styles that are described below. By doing this second fermentation with the dried pomace, this style of wine has raisin-like notes that give it a fuller, richer flavor.

Amarone - Amarone may translate to “big bitter” but don’t let that fool you. This style has concentrated flavors of dark fruit and raisins. This is achieved by drying the grapes on mats, racks (see photo) or hanging them from rafters for extended periods (weeks or months) after harvest. Known as the appassimento process, the dried fruit concentrates the flavors and sugars. The result is a wine with big flavor and alcohol levels that can reach up to 17% ABV.

Recioto - This is a dessert wine made from dried grapes. Similar to the process for used for Amarone, this fruit is dried for up to 200 days. This further concentrates the flavors and sugars. The dried grapes are then used to produce this wine but the fermentation is halted before all of the sugar is converted to alcohol. This results in a very sweet wine that still retains its natural acidity.

Wine Fun Fact: Blanc de Blanc versus Blanc de Noir

Having just wrapped up the holiday season when a lot of Champagne and sparkling wines are enjoyed, I came across a Blanc de Blanc Champagne. At first it seems that ‘Blanc de Blanc” is just a fancy name for a French Champagne. But, this is just another example of something in the wine world that is seemly complex or confusing that is really rather simple.

If you took high school French, which I didn’t, you’d know that ‘Blanc de Blanc’ literately translates as ‘White from White.” Okay, you might ask, but what does that have to do with Champagne? The answer to that question requires a very quick review of how Champagne is produced. French Champagne is traditionally produced from three grapes - Chardonnay, Pinot Noir and Pinot Meunier (Pee-noh Mehr-n'yay). The Chardonnay is a white grape, while the Pinot Noir and Pinot Meunier grapes are black.

So, you may have already gotten ahead of me. A ‘Blanc de Blanc’ or ‘White from White’ means that this type of Champagne is made solely from white grapes, namely Chardonnay.

Conversely, a ‘Blanc de Noir’ simple translates as ‘White from Black.’ Thus, it is a Champagne made from black grapes - Pinot Noir and Pinot Meunier. And, as we’ve learned, the juice from all grapes is clear - it’s the grape skins that give it the red color. So, in a ‘Blanc de Noir’ the Pinot Noir and Pinot Meunier grapes are pressed but the juice is not given any time in contact with the dark grape skins and therefore remain ‘white.’

So, in summary, you can have Champagne in three different styles:

• Traditional Champagne - Produced with Chardonnay, Pinot Noir and Pinot Meunier

• Blanc de Blanc Champagne - Produced with Chardonnay

• Blanc de Noir Champagne - Produced with Pinot Noir and Pinot Meunier