Study in collaboration with the University of Turin
DISAFA Enology, Alba site

CLARIFICATION OF WHITE WINES

THE IMPACT ON PHENOLIC COMPOUNDS

State of the art

Clarification is one of the fundamental stages in the processing of musts and wines and makes it possible to achieve outcomes that strongly influence wine quality. Different fining agents can affect different wine components; therefore, it is essential to select the most suitable product to meet the objectives defined for producing a high-quality wine.

To better describe chromatic effects, harmony, structure, and antioxidant capacity, the impact of clarification was investigated using different types of fining agents on Arneis (macerated) and Favorita (non-macerated) white wines, with a focus on phenolic compounds, color, antioxidant power, and resistance to oxidation.

Study structure

This study evaluated clarification in two wines (Arneis and Favorita) treated with eleven AEB products plus an untreated control, for a total of 72 samples. Each treatment was performed in triplicate, using 80% of the maximum dosage indicated in the technical data sheet.

After agitation and storage at 10 °C for 5 days, the samples were analyzed. The products tested included bentonites (BENTOGRAN and BENTOGRAN Rapid), gelatin (GELASIL), potassium caseinate (MICRON 96), PVPP (POLYCLAR V and POLYGEL W), decolorizing carbon (DECORAN), vegetable proteins (VE-Gel and VEGA-Gel), and complex formulations such as MICROCEL AF Plus and CATALASI Vega.

The analytical plan investigated total polyphenol index (TPI); color using the CIELab method and absorbance at 420 nm; antioxidant power (DPPH); precipitable tannins (methylcellulose method); flavan-3-ols and flavonols content (HPLC); and redox potential through a hydrogen peroxide test.

Observations

Clarification reduced the phenolic fraction and color to varying degrees, depending on the fining agent used. Notable results emerged from the CIELab analyses, which make it possible to model clarification by selecting the most appropriate clarifier to obtain a chromatic profile consistent with the desired wine style.

Bentonites (BENTOGRAN and BENTOGRAN Rapid) ensured effective clarification, while vegetable proteins (VE-Gel and VEGA-Gel) provided the best balance between chromatic stability and phenolic reduction. Carbon (DECORAN) particularly at the applied dosage stood out from all other treatments, markedly reducing all the parameters evaluated. POLYCLAR V and POLYGEL W effectively purified the wines but weakened antioxidant power, unlike MICRON 96, which proved to be the most effective in preserving antioxidant capacity while balancing nucleophilic catechins. Future LC-MS data will further clarify the impact on secondary phenolic compounds.

DISCOVER THE AEB LINE OF CLARIFYING PRODUCTS

Study in collaboration with the University of TurinDISAFA Enology, Alba site