Color of Seyval blanc Juice and Wine as Affected by Juice Fining and Bentonite Fining During Fermentation

¹ Department of Food Science, University of Arkansas, Fayetteville, AR 72704.

Two experiments were conducted to examine the effects of fining agents applied prior to and/or during fermentation on the color of Seyval blanc wine. In experiment one, kieselsol (Ke) at 719 mg/L; polyvinylpolypyrrolidone (PVPP) at 719 mg/L; bentonite (Bn) at 960 mg/L; combinations of these levels of Ke, PVPP, and Bn; sulfur dioxide (SO₂) at 100 mg/L; and a control were applied to the juice. The juice was analyzed and then fermented. Wine was analyzed initially and after two months of storage at 37°C. The Bn + PVPP and Bn + Ke + PVPP treatments improved juice and wine color (Color Difference Meter and absorbance at 420 nm) as compared to the control and provided results similar to those for the 100 mg SO₂/L treatment. The Ke treatment adversely affected color. In experiment two, Bn was applied to juice and/or during fermentation. All Bn applications improved juice and wine color as compared to the control. Bentonite added both to juice and during fermentation reduced browning to the same extent as did SO₂. Storage for two months at 37°C increased browning of all treatments except the SO₂ treatment in both studies, showing a need for an antioxidant at bottling.

Key words: bentonite, kieselsol, juice, polyvinylpolypyrrolidone, sulfur dioxide, wine color, phenolics, catechol oxidase

Submitted on October 22, 1993

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