Loss of Pinot noir Wine Color and Polymeric Pigment after Malolactic Fermentation and Potential Causes

Abstract

Loss of Pinot noir wine color and polymeric pigment due to malolactic fermentation (MLF) and potential causes for these losses were studied. Delaying MLF was investigated as a method to minimize loss of color and polymeric pigment. Pinot noir wines were held at 13°C for 0, 14, 28, 100, and 200 days before inoculation with Oenococcus oeni strain Viniflora Oenos to induce MLF. Delaying MLF did not affect loss of color, but delaying MLF for increasing times reduced the loss of polymeric pigment and after 200 days no losses compared to the control were noted. The role of acetaldehyde and/or pyruvic acid degradation by O. oeni during MLF was investigated as a cause for reduced polymeric pigment formation. Wines that had undergone MLF were supplemented with acetaldehyde and/or pyruvic acid to the levels measured in control wines that did not undergo MLF. Wines made with added acetaldehyde had more color and polymeric pigment than MLF wines with no additions, and those made with added pyruvic acid had no change in color or concentration of polymeric pigment. However, addition of acetaldehyde did not completely prevent loss of color after MLF, and color loss due to fining by O. oeni was explored. Wines that did not undergo MLF that were exposed to inactivated O. oeni cells showed no difference in color, polymeric pigment concentration, or monomeric anthocyanin concentration compared to the control wines, suggesting that loss of color during MLF was not due to fining by O. oeni cells.