Wine Turbidity (Fining & Protein Stability)
At various stages during maturation, wine is treated with fining agents, since unrefined wine is quite turbid and hazy. The turbidity is due to suspended solids produced during fermentation. This cloudiness is what winemakers refer to as protein haze, or haze for short. Thaumatin-like proteins and chitinases are the primary grape proteins responsible for haze formation. These positively charged proteins degenerate and stick together, resulting in undesirable flocculent clouds and visible haziness.
Bentonite clay is commonly used as a fining agent in wine. Fining, or clarifying, is the process of removing substances that contribute to haze by binding them through adsorption. Bentonite is negatively charged and incorporated into the wine as a colloid (fine powder mixed with water). The negatively charged clay binds to the positively charged protein molecules. After treating the wine, the particulates settle out, transforming the beverage to a desired color and clarity. This process also makes the wine more stable, meaning the wine’s signature taste, aroma and appearance won’t change appreciably while in storage.
It is common to perform a protein stability test in addition to fining trials to understand if fining is required and how much bentonite would be appropriate for the addition. It is important to know exactly the amount of bentonite to add to your wine because if added in excess it may strip the stock of color and flavor.
A selection of portable and benchtop turbidity meters are available and include a version made specifically for wine.
Below are the most common conductivity products for measuring tartrate stability during the wine making process.
For the Winemaker we offer a precision benchtop turbidity meter that can measure turbidity from 0.00 to 4000 NTU. Turbidity meters are available based on EPA or ISO methodologies. The ISO method is suitable for red wines due to it using an infrared LED as a light source. The infrared light is outside the visible spectrum and has less interference to samples that are colored.
A variety of portable meters are available to measure turbidity. For the Winemaker we offer a portable turbidity meter supplied with reagents and equipment necessary to measure bentonite.
In this category are the calibration standards used to calibrate the turbidity meters.
Accessories include cuvette cleaning solutions and cloths used to keep the cuvettes clean along with replacement cuvettes as needed.