You pose a question that is as much about skill and convenience as it is in comparing which juice to which grape.
Let me first qualify my response by stating that with directions that can be found in the related articles section of this article, anyone - including a novice - can make wine from fresh grapes.
As a devout "fresh graper", I personally view Juice as filling one of three needs:
a) a means for getting new people making wine without great stress - especially when they set about doing it on their own.
b) a means for more advanced wine-makers to extend their interest beyond what for us at juicegrape.com and M&M produce is becoming a two-season year.
c) a means for making some wines of types that are generally not locally available in fresh grape form. For example, grape juice sourced from Italy.
Juice versus Fresh Grape - Quality Standpoint
Either a juice or a must made from fresh grapes can ultimately be made to have the same Brix (measure of sugar), pH, and Acid readings. Juices have been "pre-adjusted" according to the manufacturer's preference, which includes ensuring pre-fermentation stability.
Fresh Grapes do not come adjusted. Some receive some topical treatment of sulfite to inhibit degradation during the trip to the market, but once crushed and destemmed, it is the role of the winemaker to ensure the readings are as they should be.
Juices of white varieties must be highly sulfited to prevent oxidation during storage. Expeditious processing of white varieties during a winemaking process using fresh grapes could eliminate the need for such high sulfiting.
When looking at red varieties it is important to recall that in fresh grape fermentation, color is extracted during the primary fermentation phase. Because red juices do not follow this process sufficient color needs to be added into the juice such that the winemaking outcome would yield a similar product as to that produced from the fresh grape process.
This is really where the important differentiation should be noted. Wine made from fresh grapes leaves the decision making process to the winemaker. Realistically, more decisions equates to a greater potential for winemaker error. Conversely with directions or accumulated experience and the skill that comes from it, increased control over the decisions will allow the winemaker to craft a wine that is uniquely his or her own.
Some practical reasons to use juice...
Here is a list of reasons juice might be preferential:
1. You are interested in quickly (6 - 8 weeks) making a batch of wine just so you can get a general feel for the winemaking process.
2. You do not own or have access to crushing, destemming, and pressing equipment. M&M does offer the crushing, destemming, and pressing services if so desired. *** Remember that ideally reds will ferment first before pressing, which with fresh grapes would mean needing access to some type of press ***
3. You cannot get fresh grape for the type of wine you wish to make and it is available only in juice form.
Now, the specific questions that were asked...
1. Is there a significant difference between the two? Assuming both the juice and grape came from the same vineyard - meaning we are talking equal grape quality; the significance would only be in your absolute control over the winemaking process and proper color extraction for reds.
2. Is one more stable than the other? Well, juices are packaged to be stable. This is more like a fresh or frozen argument...frozen is certainly more convenient. If you’re planning on making wine on the day of your purchase, how stable does it need to be?
3. Do I have a better chance of getting a better finished product from one or the other? I'd argue that your potential for the best finished product would come from the fresh grape. However, given the additional variables that weigh heavily on winemaker skill, one could argue that juices provide a repeatable formula for getting consistently decent and increasingly good wines.
Nick Coppola
Juicegrape.com Support