Specific Gravity of Fruit

[Chris Pittock]

This is a technique type question and something that I have been wondering about for a while.

When I make wines from juices, tinned fruit or packaged fruit, the sugar content is listed on the labels so I can work out how much sugar to add to get the results I want. If I am using just juices I can take a hydrometer reading to check I have the S.G. I want.

However, if I use picked or loose fruit I don't know how much sugar is contained so I have to guess. If I add this fruit to juices and/or water in a fermentation bin, using a hydrometer right at the start won't tell me how much sugar is still in the fruit as it won't have been released. Therefore I risk adding too much or too little sugar. In fact last year I did add too much sugar and ended up with an extremely sweet wine. I ended up blending with another very dry wine, which happily worked very well.

Is there a way I can do better than just guess the sugar content of a given fruit?

 

[dralarms]

Freeze the fruit and thaw or steam juice the fruit. Wine makers take a sampling by taking a few grapes and squeezing the juice out and measuring the sugar content using a refractometer

 

[Stressbaby]

Luc's wine blog has some experiments on this you might find helpful. I don't think he posts on this blog much any longer but it is still up.

Here he compares different methods. Steam juicing (not surprisingly) fares poorly: http://wijnmaker.blogspot.com/2008/09/appeltje-voor-de-dorst-apple-day.html

Here his experiment shows you have most of the sugar out by 48 hours: http://wijnmaker.blogspot.com/2011/01/

 

[mainshipfred]

I'd buy the refractormeter, they are really cheap and will make the testing much easier.

 

[Rice_Guy]

This is a technique type question and something that I have been wondering about for a while.

When I make wines from juices, tinned fruit or packaged fruit, the sugar content is listed on the labels so I can work out how much sugar to add to get the results I want. If I am using just juices I can take a hydrometer reading to check I have the S.G. I want.

However, if I use picked or loose fruit I don't know how much sugar is contained so I have to guess. If I add this fruit to juices and/or water in a fermentation bin, using a hydrometer right at the start won't tell me how much sugar is still in the fruit as it won't have been released. Therefore I risk adding too much or too little sugar. In fact last year I did add too much sugar and ended up with an extremely sweet wine. I ended up blending with another very dry wine, which happily worked very well.

Is there a way I can do better than just guess the sugar content of a given fruit?

There are tables of what is typical / average. , , In the US I could pull out a hard copy of “USDA hand book 8” or for less extensive info go to a nutrition textbook / CD nutrient calculator program / weight watchers web site. The EU should have similar available.
Crops will vary and generally speaking be higher sugar the longer they are on the plant. I will juice at least 50 ml of any ingredient I debate using, to find an actual value.
For tinned/ packaged foods the nutrient info should equal handbook 8.

 

[salcoco]

https://winemaking.jackkeller.net/index.asp this is right url

 

[salcoco]

I believe Jack Keller has a list of potential sugar levels on his web site https://winemaking.jackkeller.net/index.asp

 

[Chris Pittock]

Thanks guys, that's been very helpful. Are those refractormeters I've seen on eBay any good and easy to use?

 

[mainshipfred]

I'm sure some are better then others but mine was $25.00 I think and works just fine.

 

[salcoco]

there are digital and analog versions . the should be temperature compensating. Amazon should also have some. they are internally used to measure the sugar of fruits, grape and a wine must. they can also be used to monitor the fermentation although alcohol will cause a distortion of the reading. there are spread sheets on the internet that can be used to calculate the real specific gravity. since they only need a drop of fluid to make a measurement they are a lot more handy than a hydrometer.