Sour vs. Sweet juices

[Charlesthewino]

Do sour grapes make sweet wine? It seems the more recent wines I've made with sweet grapes have ended up as sour wines. Last fall my sour grapes seemed to make sweet wine. Is there any rationale to this?


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[Turock]

Not sure I understand what you're saying. Describe these wines--what kind are we talking about?

 

[DoctorCAD]

All of the sugars ferment taking any sweetness out, assuming a full ferment.

 

[salcoco]

I would guess that you are not testing for sugar or acid. the sour wines were to acidic the sweet wines did not finish fermentation. I would suggest getting some literature on wine making and learn how to test for sugar, acid and proper yeast nutrition.

 

[Charlesthewino]

I guess what I am asking is...assume all factors are equal except for the type of grapes. I have home grown seeded white grapes (not sure exactly what grape as they were planted by the previous homeowner). When ripe, these grapes are very sour when picked fresh off the vine. I made wine from these sour grapes and the end result was a semi-sweet wine. In contrast, I recently made wine from sweet Concord grape juice and the end wine seems sour. So if you assume a starting SG of 1.090, Ph levels are equal and approximately the same amount of sugar added to both juices...will sour grapes produce a more sweet wine? The alcohol is produced from the sugar both natural and added. If sour grapes have less natural sugar that assumes the alcohol content produced is also less. So would the sour grapes just have less alcohol or would they taste sweeter also?


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[Charlesthewino]

Also assume full fermentation to say an SG of .995.


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[blackspanish777]

I think you need to check the acidity of the grapes before just to see if they will even ferment.

 

[sour_grapes]

So if you assume a starting SG of 1.090, Ph levels are equal and approximately the same amount of sugar added to both juices...will sour grapes produce a more sweet wine? The alcohol is produced from the sugar both natural and added. If sour grapes have less natural sugar that assumes (sic) the alcohol content produced is also less. So would the sour grapes just have less alcohol or would they taste sweeter also?

There are a lot of contradictions in your assumptions. If you assume that both have the same starting SG, and ferment to the same level, then they will have the same alcohol content. They will also have the same sweetness. If you assume they have the same pH, then they will probably have the same level of sourness.

 

[Charlesthewino]

I guess I am no closer to an answer. Sour juice or sweet juice ends with the same wine? Certainly the natural sugars in the fruit has some effect here.


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[sour_grapes]

Sugar is sugar. The yeast don't care whether they are "natural" (whatever that means) or derived from other sources (unnatural sources?)

 

[salcoco]

what are the measurements you made for the two wines. the only way wine will differ in the end is due to acid or poor fermentation. the sourness or sweetness of the grapes to start are modified by the addition of sugar and addition or removal of acid. In the end done properly the grape should come out with the same profile.
back to original question did you add sugar or acid to any of the wines. what are the measurement values.

 

[Turock]

I'm just really confused by this question. When you take your initial SG (brix) reading of the must, the highest brix we've ever found is 6. Add sugar to bring it to a brix of whatever potential alcohol content you desire, then ferment to dry. If you're having wines that have a sweetness to them at the end, then the ferment did not go to dry--usually because of poor nutrient management.

You should always be taking PH readings and make adjustment of your musts before you begin the ferment. This produces balanced wines.

It seems to me that you may have a couple issues going on here---lack of PH adjustment, as most fruits need SOME adjustment, and possibly not using nutrient correctly. Maybe you can fill us in on how you are doing your ferments--that may give some more clues as to your difficulty. Concord is more like a fruit than a grape and almost always needs PH adjustment.

 

[Charlesthewino]

Thanks for the input. I think a I have a better idea of what happened. There are a few issues here. The assumptions are that both wines are equal when they were not. I was trying to get information on a hypothesis. The first batch using the sour grapes was made prior to getting any real measurement equipment (hydrometer, Ph meter, and acid adjustment mixes). I don't know what the initial readings would have been. It is entirely possible that the sweetness is a result of incomplete fermentation.

Secondly, my Ph reading and adjustments have all come post fermentation as I have only recently obtained the Ph meter and the ability to adjust the must. All adjustments were made to existing batches. Going forward, I will make Ph adjustments at the initial process.

As it pertains to nutrient management...I have not done any. Not sure where to start. What am I to measure and how do I make adjustments? From what I've read, the nutirents are added at the beginning of the fermentation process. Are there adjustments that can be made post fermentation? Again, I appreciate the input.

 

[Turock]

Charles---Making pre-ferment PH adjustments is the way to go. Adjustments get integrated better and on some ferments where you are starting with very acidic fruits, you'll find that if you don't adjust pre-ferment you may not be able to fix it in the post ferment. You'll avoid a lot of problems and time expense if you work at the primary instead of the secondary.

When you are feeding nutrient, the main component you are providing the yeast is nitrogen. Yeast needs it in the correct amounts and at the correct time during the ferment to keep the yeast healthy and unstressed. When yeast gets stressed, the ferment can be sluggish, stuck and/or produce H2S. Nitrogen also increases the yeast's tolerance to alcohol.

Always step-feed nutrient. If you're using regular nutrient which is DAP, calculate the full dose for the gallons of wine you're making and split it in half. First dose goes in when the yeast takes off, and second dose at 50% sugar depletion. This way, your ferments will always go to completion.

 

[Charlesthewino]

Turock - Thanks for the input. I have a pending supply order. Do you have any suggestions for the nitrogen additive that I should order? Any preferred brand?


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[Turock]

Well, DAP is DAP. You can use Fermaid K if you want to. If you use Fermaid K, you should use Go-Ferm to rehydrate your yeast. You can read all about Fermaid products at www.scottlab.com