Welcome to the wine lab
MADRID – Winemaking involves as much chemistry as it does art.
That’s why a wine laboratory is as essential in a winery as a fermentation vat or a bottling line.
“It’s important to have a good lab at your location,” said Dr. Murli Dharmadhikari, an Iowa State University Extension enologist and director of the Midwest Grape and Wine Industry Institute. “Testing your wine helps you measure how your wine is evolving, plus it helps you focus on consistency of production, while ensuring that you meet established regulatory standards.”
Dharmadhikari provided hands-on examples during a Nov. 13 wine analysis workshop at Snus Hill Winery near Madrid. He covered three lab procedures every winemaker should know and use, such as measuring pH, titratable acidity and free-sulfur dioxide.
The pH value is a fundamental element of winemaking, Dharmadhikari said.It strongly influences wine properties such as color, oxidation, biological stability and chemical stability.
The pH level reflects the strength of the acids that are present.
“Lower pH values are better if you’re a winemaker,” Dharmadhikari said.
Acids not only contribute to the pH of wine, but provide wine’s crisp, tart taste, he said.
If there is too little acid, a wine will be flat or flabby, while too much acid makes the wine sour tasting.
When acids are properly countered by other ingredients – alcohol, sugars and trace minerals – the wine is said to be in balance, which is the desired end result of all winemakers.
The largest percentage of acidity in wine comes from three primary types of acids, including tartaric acid, malic acid and citric acid.
Cold-hardy grapes like those grown in Iowa have much higher levels of malic acid, followed by tartaric acid and citric acid. It’s important to measure acid levels in wine and check titratable acidity, said Dharmadhikari.
Attending the workshop was a wide range of skill levels, from long-time commercial winemakers, experienced hobbyists and beginners like the Phillips family from Lake View.
“There’s a lot to learn about winemaking,” said Marsha Phillips, whose son, Andrew, is working with her and her husband, Norm, to open Rustic River Winery in Sac County. “This was a good opportunity to gain some hands-on experience with wine testing.”
One of the most challenging aspects of winemaking is ensuring the integrity of the final packaged product.
Sulfur dioxide is important in the winemaking process, Dharmadhikari said, since it aids in preventing microbial growth and oxidation.
He outlined the various forms of sulfur dioxide and demonstrated how to measure sulfur dioxide.
“Now you can take a good night’s rest, knowing that your wine is protected,” he said.
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