The Extraction of Condensed Tannins in Red Wine Production

A commercial scale maceration trial was set up with two wineries, Wente Brothers and Sebastiani Vineyards. Cabernet Sauvignon grapes were harvested from four vineyards, two lots going to each of the wineries. In each case, five wines were made in 20 ton fermentations. The fruit was distributed between all fermentors. The treatments were a control, delayed fermentation, extended maceration, an oak tannin treatment, color extracting enzymes and rotary fermentors. The phenolic composition of the wines was tested using the Folin Ciocalteau, spectral tests, and both reverse and normal phase HPLC procedures. In general, the differences between vineyards were greater than those of the treatments. One of the most notable features was that many of the treatments did not cause consistent changes. The delayed fermentation increased phenol levels slightly, the extended maceration had very little effect on total phenol except for one vineyard which increased significantly, while the rotary and color extraction procedures had little effect. Only the oak tannin treatment significantly decreased the total phenols. Treatments did have trends for specific components. The extended maceration did increase catechin and epicatechin while it decreased unbleached anthocyanins as well as monomelic anthocyanins in most but not all wines. Catechin and epicatechin levels were very low in the wines with short maceration time, those in the oak tannin and color enzyme treatments, although the short but intensive rotary treatment had mixed results. The ratio of small to large tannin was not affected by any of the treatments. In conclusion, none of the treatments significantly altered any of the wines total phenol content consistently except to decrease when short contact times were used, and some individual compounds did respond to treatments.