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Overcompensating With Copper

TroubleShooting

Craig Bedard — Calgary, Alberta asks,
Q

I made about 21 gallons (80 L) of wine with Sangiovese grapes and Lalvin EC-1118 yeast. No other additives were used. I should have used a yeast nutrient. My wine smelled like boiled eggs. I added about nine copper nails and copper pipe tube straps. I let them sit in the wine for about a month. The wine has a slightly less “eggy” smell. It now tastes very metallic/coppery. How would you remedy this?

A
Ah yes, Monday morning quarterbacking is always tough when it comes to wine. Adding a complex yeast nutrient (a mix of nitrogen, amino acids, and other micronutrients) is something I do with every fermentation. I have the luxury of being able to send my musts and juices to a wine lab to measure their amino acid and nitrogen content, but even when the available nitrogen levels are sound (about 300 ppm YAN or yeast assimilable nitrogen) I still add a tiny bit of a DAP-free complex yeast nutrient mix to make up for any deficiencies but not further increase nitrogen levels. Indeed, it’s most often a lack of nutrition that makes a fermentation, and the resulting wine, smell like rotten eggs (hydrogen sulfide). Adding copper is certainly something that can help, but, rather than dumping in bits from the hardware store, next time use measured and metered amounts of a copper sulfate solution (CuSO4). You can buy CuSO4, along with directions for use, from many winemaking suppliers. Because too much copper can be toxic to humans, and because it seems
Response by Alison Crowe.