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Grape Seed Extracts Reduce Formaldehyde Levels in Leather Production

by Becca • November 12, 2012 • Comments Off on Grape Seed Extracts Reduce Formaldehyde Levels in Leather Production

I’ve covered the topic of the recycling of wine industry a lot lately on The Academic Wino, as it is it becoming increasing more desired in the wine business to not only decrease the contaminants and potentially toxic chemicals in…

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What IS “Local Wine” Anyway?: A Study on Defining “Local Wine” to Wine Consumers in Ontario

This post highlights and summarizes a new research article on how consumers define local wine.

White Wines with a Different “Dimension”

Mauro Cirilli is the wine director of Perbacco ristorante + bar and the newly opened barbacco eno trattoria. While living in Italy, Mauro attended the three-year Italian Sommelier Association Program and worked as sommelier at the celebrated il Cibreo. He went on to work as assistant sommelier at the renowned La Rivista in the Hotel Ca’ Pisani in Venice, as well as five-star hotels, including Hotel Baglioni and Hotel Danieli. Mauro moved to San Francisco in 2001, and became the lead sommelier at Aqua. In 2006, Perbacco opened with Mauro as the wine director, garnering a number of national wine awards. With the Perbacco team, Mauro opened barbacco eno trattoria in 2010, and continues to oversee both wine programs.

White Wines with a Different “Dimension”

You may be thinking, “What is this all about?”

You may already know that white wines are made slightly differently from red wines. While with red wines the skin and seeds are kept in contact with the juice during the fermentation for a period of time to allow extraction of color and tannins, with white wines usually the skins and seeds are removed immediately before fermenting.

In the last fifteen to twenty years, things have changed. A few producers from Italy, mostly from the northeast regions, have been experimenting with a very old and almost forgotten technique of longer skin maceration for white wines. While in the last century, the market required a more pristine and clean style of whites, which commands more manipulation; these winemakers are going back to how wine used to be made thousands of years ago, when technology did not exist and the product was more natural.

Why are they doing that?

Contact with the grape skins extracts not only color and tannins, but also minerals that bring to the actual wine a different “dimension.” It is best to say that these wine producers are very strong believers in natural winemaking, where wine must represent the unique terroir of the vineyards.

To describe these non-conventional wines, wine journalists around the country started using the term “orange wines,” referring to the color that can vary from a dark yellow-orange to dark-golden brown. For me, the most exciting thing is not the color, but the dimensions of these wines; I’m referring to their texture, mouthfeel, and depth.

This style of white wine is denser and richer, with good weight on your palate. The presence of tannins and minerals add more complexity and a full flavor profile. They have unique aromas that can vary from apple or pear cider to warm spices, from baked fruit to earthy notes. Because of their texture and depth, these wines are very food friendly. They are definitely different compared to many other everyday whites available in the mainstream market.

I grew up in the Veneto region of Italy, where a few producers are following this ancient winemaking method. Here are two most notable ones:

Angiolino Maule, from the town of Gambellara, 25 miles east of Verona, makes one of my favorite whites, Sassaia, which is made with Garganega and Trebbiano grapes. He believes strongly in organic viticulture, where the use of chemicals is totally avoided in the vineyard in order to protect all the micro-organisms present in the soil. The vine roots are therefore able to extract important minerals from the volcanic soil of the vineyards.

After harvest, he macerates the grapes with skins and seeds for 24 hours, and then begins fermenting without using any added yeast except the indigenous one present in the grape. The wine is then aged in large barrels for almost 10 months before it is bottled without any filtration.

Sassaia is so different from any other white wines produced using Garganega and Trebbiano: the color is lightly orange, with aromas of apple cider, orange peel, honey, and nuts; and its texture is quite remarkable, with the presence of light tannins and great minerality.

Alessandro Sgaravatti is the owner Castello di Lispida, located in the same town where I was born, Monselice, just 15 miles south of Padova. Sgaravatti is a disciple of Josko Gravner, the pioneer who revived this old method of vinification. (Gravner, during a trip to Georgia in the former Soviet Union, mastered an ancient winemaking technique that dates back five thousand years, where grapes are placed in large clay amphorae, buried in the soil, and left to ferment in contact with skins and seeds for a very long time.)

Sgaravatti makes a wine named Anfora, using Friulano grapes (previously know as Tocai Friulano) following the technique he learned from Gravner. He puts the grapes in the amphorae so that their juice goes through maceration and fermentation in contact with skins. After six months, the skins are removed and the wine is left to age eight more months.

During this process there is no use of any temperature control, no addition of sulfites, and no filtration. This wine has a dark cloudy orange color, with lots of earthy aromas, warm spices, and resins. The texture is bold, very dense and thick, with tannins and minerals present in good quantity…a wine that truly comes from the soil!

Sgaravatti believes that wine is a natural product and has to be treated in a natural way. He once explained to me his philosophy behind the use of amphorae: “Grapes take nutrients from the soil through their plant. When we put them into an amphora made of clay, we bring them to their natural origin. During the fermentation, the grapes exchange energy with the soil, so the amphora works as a natural link between the two elements.”

Maule and Sgaravatti are just two examples of producers that are going back to the old, traditional winemaking technique that unfortunately had almost been forgotten. It is going back to our original roots; the connection between the man, the vine, and the soil.

Grape seed color has little effect

Winemakers have long held that the changing color of a grape’s seed serves as a harvest signal, that the greener the seed at harvest, the more tannin characteristics and bitter taste imparted to the wine.

However, researchers at Washington State University have found that changes in seed color have less to do with wine tannins than previously thought.

In fact, their results after one year’s study were so different — and opposite — from what was previously thought, they completed a second year of study to confirm the results.

“It’s an interesting one, mostly because we don’t think winemakers should be paying attention to seed browning,” said James Harbertson, associate professor of enology at the Chateau Ste. Michelle WSU Wine Science Center in Richland, Washington. “It just doesn’t really change how much tannin gets extracted in the wine.”

The project was born, Harbertson said, by an argument. He and former WSU doctoral candidate Federico Casassa of Argentina, now an assistant professor of enology at California Polytechnic State University’s wine program, both believed that if winemakers have more green seeds at harvest, they’ll end up with horrible, bitter-tasting wine that no one will want to drink.

The argument centered on whether the theory could be tested.

“He didn’t think we could actually do the study as we designed it. It was a debate about experimental design,” he said. “We came up with three-fourths of the parameters and had discussions about controlling for different things. It was fun, because we really got into it and eventually finished the experimental design.”

Embarking on the research

A previous study in Australia established a color schematic showing the development of wine grape seeds, with the color progressing from an olive green to an almost coffee-colored brown.

The study, however, lacked information about tannin concentration and what happens if wine is made at each of these different color points, Harbertson said.

The researchers selected a typical cultivar in Washington, Merlot, which is one of the earlier-ripening red wine grape varieties in the region, and the Paterson Ranch of Ste. Michelle Wine Estates in Paterson, Washington.

The vineyard, which was planted from 2000 to 2003 with clone 3 and row spacing of 7 feet in a north-south orientation, is drip irrigated.

The grapes first were picked relatively early, Sept. 22, 2011, at a soluble solids of 20°Brix.

Few growers and winemakers would consider picking 20°Brix fruit today, Harbertson said, and the researchers figured that “if you don’t see any difference in tannin extraction and sensory profile at this level, you won’t see it at all.”

They divided the must — the freshly pressed juice that includes the stems, skins and seeds — into two lots. One served as a control lot, while sugar was added to the second lot to push it to 25°Brix and to increase alcohol levels, a process known as chaptalization.

The researchers made wine from both lots twice: after a standard maceration time of 10 days and after an extended maceration time of 30 days.

Maceration is the cold-soaking process by which the grape skins, seeds and stems leach the phenolic materials of the grape — tannins, anthocyanins or pigments, flavor compounds — into the must and, ultimately, the juice. It’s where red wine receives its color.

The researchers harvested fruit again 33 days later on Oct. 25, 2011, when the fruit finally ripened to 25°Brix. They repeated the process, except this time, instead of adding sugar to one lot, they bled the juice and watered it down to reduce it to 20°Brix. This enabled them to work with more mature fruit with lower alcohol levels.

They followed the same process again in 2012, harvesting on Sept. 13 and Oct. 17.

The results

Wines without extended maceration had significantly higher anthocyanin content, saturation and red color component, whereas the extended maceration wines had enhanced tannin extraction from seeds, lower anthocyanin content and lower saturation.

The sugar level and alcohol content showed no significant effect on tannin and anthocyanin extraction, the study found.

In terms of sensory profile of the wine, those made under extended maceration showed higher astringency, lighter and yellower color components and cooked vegetal aromas. Chaptalization of early-harvest fruit to 25°Brix shifted the sensory profile to a sweeter taste, alcoholic, floral, with chocolate/caramel attributes and higher astringency.

The later harvest date, meanwhile, had an even more positive effect on the sensory profile of the wines than maceration length and sugar and alcohol levels: Wines from the late-harvest fruit were defined by viscous mouthfeel (the wine feels heavier, thicker in the mouth), sweet taste and fruit-derived aromas.

Overall, unripe fruit and the application of extended maceration had a negative impact on the sensory profile of the wines, whereas chaptalization of unripe fruit yielded wines with an improved sensory profile.

“Seed tannin extraction didn’t really matter if you had really unripe fruit at 20°Brix versus really ripe fruit at 25°Brix, where the grapes are more likely to be picked nowadays,” he said. “We saw there was a little bit of difference between vintages, but for the most part, it was constant depending on when you picked. When we did the sensory test, we really couldn’t differentiate the astringency.”

Harbertson said some growers might be more concerned about a red variety that is picked even earlier — Pinot Noir. “Those growers say their seeds are really, really green, and the longer they ripen, the less they worry about it,” he said. “My guess is that it takes shorter time to get from 20° to 25°Brix, so you have even less to worry about.”

The research tells winemakers and growers that seed color and tannins aren’t as important a factor at harvest, Harbertson said. Instead, they should place the emphasis on those factors that weigh more heavily and are easier to measure or taste, such as fruit color, flavor and acidity.

“Most of those things you can measure quite easily, and tannins are actually quite hard to measure,” he said. “The message is that you don’t have to spend all this money on analysis of tannins in the vineyard. It’s not as mission critical, especially if the vineyards are trying to do some of that themselves.”

The study was published in the American Journal of Enology and Viticulture in 2013. •