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Reductive Resolutions


Jeff Griffin — Felton, California asks,

For the last two vintages, my Chardonnay, fully dry and through partial MLF (stopped with SO2) went into the bottles after a few months of settling and a couple of rackings. I Add inert gas while aging as well as keeping it topped up in the carboys and now my new variable volume tank. At bottling it always smells fine, but in about 3 months, it develops swampy, reductive odors. A day sitting in open air resolves the smell, but it’s awkward to give a bottle away and have to tell the recipient why it smells bad and how to fix it. Any advice on how to prevent this next year?

Your question about how to avoid a swampy, reductive odor in your Chardonnay after bottling is an interesting one. For readers who may not be aware, “reductive” is a non-exact sensory term often used to signal rotten egg or hydrogen sulfide-type aromas. Hydrogen sulfide in wine can be caused by a few different things but is most often produced by Saccharomyces cerevisiae during fermentation, usually due to a nutrient or amino acid deficiency. Since you don’t specifically mention rotten eggs here, and because you say your wine smells fine right before bottlings, I’ll assume we’re not talking about a classic “rotten egg” hydrogen sulfide problem. Ruling out hydrogen sulfide and the related mercaptan and sulfide-containing compounds that are corollary defects, I’m assuming you’re talking “swampy and reductive” in a more general sense. Not knowing more particulars is tough, but since the defect seems to be catalyzed when you bottle your wine, let’s investigate a few areas. First, don’t bottle your wine too soon. Sometimes, right after harvest, I go to the winery and want to take a 750 mL bottle
Response by Alison Crowe.