Ask Wine Wizard

Importing Juice vs. Fresh Grapes

TroubleShooting

Ralph Obernauf — Bridgewater, New Jersey asks,
Q

I have been making wine at an “urban vintner” in New Jersey for about 15 years. I have always ordered grapes and crushed/pressed them using their equipment. Last week I bought a barrel of Chilean Merlot and they advised me to buy juice rather than grapes. They said if you crush soon(er) after picking you get a better wine. What is your opinion?

A
Well, it seems to me that Chile to New Jersey is an awfully long haul. I often, in my blog and in this column, advocate that the distance from vineyard to crushpad be as short as possible. Your friends are right; distance and, especially, time, can cause a degradation of quality. When a grape cluster is removed from the vine, no matter how carefully, there is some jostling and juicing that happens. Once juice is exposed to the air it begins to oxidize and begins to be degraded (read: eaten) by ambient yeast and bacteria. This all contributes to a possible increase of microbial and oxidative by-products including aldehyde production, bloom of unwanted bacteria species, and most commonly, volatile acidity (acetic acid) production. Though of course the cold storage shipping conditions help to slow these reactions down, they will still take place to some extent. When you unpack your grapes, smell critically for any off odors and see if there’s much juice in the bottom of the containers. If so, I would strongly recommend juice or concentrate. All that being
Response by Alison Crowe.