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Wine Fermentation

Wine fermentation is the process by which yeast turns grape juice (must) into wine. It relies on many complex biological pathways which all contribute to the final taste and quality of the wine. Through better understanding of these pathways wine makers are able to make critical adjustments to direct the outcome of the fermentation and ultimately improve the taste and consistency of the wine.

Use of in-line sensors to monitor critical process conditions like pH, ORP, dissolved oxygen, conductivity, and yeast activity are on the rise. These sensors provide continuous readings and the opportunity to make small adjustment 24 hours a day with minimal manual intervention.

Wine Chemistry

The vast majority of wines are composed of the same two primary ingredients: water and ethanol. What sets different wines apart is the small fraction of each bottle that contains acids, sugars, and tannins as well as a variety of compounds that influence smell and color. Wine chemistry is the practice of controlling these other components through a wide range of techniques, all of which depend greatly on measurement capabilities such as ORP, pH, and conductivity.

Sensors for Sulfate and Sulfite in Wine Making

ORP is a valuable indicator of hydrogen sulfide (H₂S) formation in wine fermentation. Online measurement can be used to precisely control initiation and duration of pumpover.

Sensors to Monitor the Stability of Microbes

Measurement of pH in wine fermentation can reveal the stability of microbes within the wine. A range of pH 3-4 should be maintained for most fermentations.

Sensors to Determine Cold Stability

Conductivity measurements are commonly used in wine fermentation to determine the cold stability of the wine product based on a correlation to the likelihood of potassium bitartrate (KHT) formation.

Dissolved Oxygen in Wine

In addition to ORP, pH, and conductivity, it is also crucial to measure and control the levels of dissolved oxygen (DO) in wine. While high levels of DO have detrimental effects on taste and shelf life, carefully controlled levels of DO during fermentation improve the flavor, texture, and complexities of wine.

DO increases as wine is exposed to air. In addition, temperature and atmospheric pressure both affect the levels of DO. Wine making in warmer, low-pressure environments is less susceptible to increased DO, while colder, high pressure settings are ripe for higher levels of DO.

The primary concern related to elevated DO is the potential for oxidation. As DO increases, antioxidants like sulfur dioxide become less effective and the wine will begin to degrade in color and lose flavor.

Measuring dissolved oxygen in wine can be done with either polarographic or optical dissolved oxygen sensors.

Dissolved Oxygen in Wine

The Importance of Yeast in Winemaking

During fermentation, yeasts metabolize sugars present in the juice into ethanol and carbon dioxide. As a process reliant on the activity and growth of Yeasts for success, controls should be implemented during the fermentation stage to ensure success. Total Cell Density (TCD) measurements are indicators of yeast activity and growth in the fermenter (by extension, the favorability of conditions within the Fermenter) and can be correlated to production yield. In-line measurements with Hamilton’s Dencytee TCD sensor enable the accurate determination of yeast growth during fermentation processes in real-time.

Interested in a demo of Hamilton's sensors?

Sometimes the only way to definitely know the value a product of a product is to try it out. That's why Hamilton offers a demo program where new and existing customers can try sensor products before committing to a purchase. Using a conditional purchase order, Hamilton will send sensors to customers for installation and trial. If the sensors work as desired, Hamilton executes the purchase order and payment. But if the sensors do not perform as expected, and the purchase order is discarded.

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