April 15, 2014

Posts Comments

Monitoring sulfur dioxide in the winery

Wine, all on its own, is a fairly good antiseptic. The tartaric acid in wines made from grapes is a relatively strong organic acid that helps keep the pH of the wines low, which in itself is a good way to inhibit microbes. Add to that the antimicrobial properties of alcohol, and you have a beverage that could help you survive through a plague. However, that’s not to say that nothing will survive in wine. Acetic Acid bacteria, Brettanomyces, and other spoilage organisms can literally turn a wine sour and make it generally unpleasant to drink. This is where the use of sulfur dioxide (SO2) in the winery is imperative. In addition to antimicrobial properties, SO2 is also an antioxidant and antioxidasic. It is arguably the most important additive in wines and, except for alcohol, is the only component in wine that requires a warning statement on the label. Thus, it is important that wineries not only ensure that they are correctly dosing and … [Read More...]


Nitrogen in the Winery

  Winemaking begins in the vineyard, and so does nitrogen. Nitrogen is one of the most common elements in the universe. On Earth, in its elemental form, it exists as a gas that forms 80% of our atmosphere. However, it is also a chemical constituent of many important components essential to life. Nitrogen makes up the building blocks of DNA, and it is also an important element in the composition of amino acids. When linked together, amino acids form the enzymes that drive all of life’s biochemical reactions. They are the building blocks to all proteins, hormones, and some plant metabolites that are responsible for wine flavor. Plants draw mineral nitrogen from the soil and convert it to amino acids and other compounds. Animals who consume plants in turn ingest the nitrogen that the plants have drawn from the soil. Even single-cell organisms, such as yeast, need nitrogen for survival.   Many of us are well aware of the effects … [Read More...]

Frontenac Gris lined up for sensory evaluation

“What Yeast Should I Use?”

The title of this post is one of the most common questions asked by winemakers working with cold-hardy grape cultivars. It is a simple question, but one that doesn’t have an easy answer. I have written on this topic in the past, so let me just throw out something that you probably haven't heard yet: your yeast choice probably isn't going to make or break your finished wine. There. I said it. I diminished the importance of yeast choice. To be fair, yeast selection does have an impact on the characteristics of your wine. Poor-quality fruit can be enhanced by choosing the correct yeast, and high-quality fruit can lose some of its potential by choosing the "wrong" yeast. The argument being made here is that your yeast choice isn't going to make the difference between a wine that is worthy of a gold-medal, and one that is worthy of being poured down the drain. When yeast choice REALLY matters, it's when the environment in which the … [Read More...]

CabernetSauvignon 7.1.13 flowering

Predicting Harvest Dates

Yesterday, I took a few pictures in the vineyards at the Horticulture Research Center near Victoria, MN. We are well behind schedule for fruit ripening - which is expected with the late spring we experienced this year. There is some hope that we could catch-up somewhat if the rest of the summer remains warm and sunny. However, years like this highlight the fact that selecting the right grape variety is crucial if you want to plant a vineyard at the extremes of where they will ripen. The following three pictures were all taken on July 1st.  All three of these pictures come from different grape cultivars, although they are planted within steps of each other. In a year as cool as this year is turning out to be, it is easy to see that simply choosing the right grape variety to plant will have a huge impact on whether or not one will see those grapes ripen before the leaves fall off the vine! The first two photos are from Vitis … [Read More...]