Should I ignore sugar content on juice labels and just take a hydrometer reading?

[Grape Expectations]

I got some Cranberry juice and on the label, the sugar content says 9.4g in 100ml, so 94g per Liter.

Measuring with two different hydrometers (that I checked read 1.000 in water at 20°C) the juice measured 1.050 SG which according to the scale and a table I found online, it's more like 136g sugar per Liter. That's a huge difference compared to the label!

I read somewhere, it might be the case that the juice makers are only putting the added sugar on their label. Does it sound likely to be the case?

I think in future I will disregard whatever it says on the label and just go off the SG level, as a basis to work out what sugar needs adding. This latest batch has ended up with so much sugar, it must be bordering on too much (it's at about 380g/L) but let's see what the ABV comes out to, if it gets there! According to the start SG, It's gained 4.1% alcohol in the first 3.5 days and now on day 5, it's still fizzing away nicely. A long way to go yet.

 

[ChuckD]

Yes.

 

[ChuckD]

I might look at labels, but only trust the hydrometer.

 

[distancerunner]

It’s one thing to mess up by trusting someone else’s numbers. It’s a whole ’nother thing to mess up when you can collect the data yourself. In the first instance you can say “Oops.” The second case is loaded with regret.

Trust but verify.

 

[BigDaveK]

Keep in mind that the hydrometer measures density and not sugar content. Sugar usually contributes most to the density but there are other components. Each fruit is different.

 

[Grape Expectations]

This cranberry is almost mocking me compared to the orange juice wine I made previously. Put it this way, the orange juice went from no alcohol at 1.120 SG, to me syphoning it off 6 days later at 0.994 SG and (presumably) at least 15% ABV - whereas this cranberry is a whole other ball game entirely, it's really stubborn, with the same yeast, nutrients, everything. I reckon it's going to take 6 weeks to ferment to 15% ABV, if it ever gets there! I have been throwing bicarbonate of soda in and panicking trying to get the pH level up (apparently cranberry juice is 2.5 pH which is about 1 lower than would be ideal for yeast) but adding the bicarb hasn't made it ferment any more vigorously. I regret adding it now (3.4g in 4.5 liters). One advantage is I'll never get any overflowing with it... because the fermentation is going at a snails pace.

I started an "emergency" batch of orange juice off because I'm not waiting 6 weeks for a drink.

You know what though... based on tasting that cranberry and yes it's really sickly sweet now, but trying to see past that when tasting, I reckon it's going to be far nicer than the orange wine. Just need to get the cranberry down under 0.998 and I'll be happy with it, assuming the bicarb taste isn't noticeable lol

 

[Rice_Guy]

Yes. Cranberry has a low pH. Yes it is likely that it stops early. No yeast will work well at pH 3.2 and crater some place below 2.8. ,,, There are several factors acting as preservative, pH is one but eventually alcohol or lack of nutrients becomes more important.

Potassium bicarbonate can give bitter from the potassium, I don’t use it for more that 0.1 pH unit. Sodium can give a salty flavor. Calcium carbonate (limestone powder) has less flavor impact so I use it for bigger jumps, I’d reacts slowly so needs to be mixed in or reacted with a small portion of the juice which is mixed back in.

 

[Grape Expectations]

Another example where the label isn't accurate:

Aldi orange juice...

This orange juice now has different packaging and it says it's got 12.1g sugar/150ml which equates to 81g/L. The old juice used to say 16g sugar/150ml which comes out to 107g/L.

That's quite a difference and yet the new juice SG reading is almost the same as last time, it's only 0.002 lower now, whereas a shift from 107g/L to 81g/L would be more like 0.009 SG.

If the drop of 0.002 SG is taken into account and if it really did have 107g/L last time (who knows!) that makes it lower from 107g/L to 101g/L. So that's how I'm calculating it, using the 0.002 SG drop, because I know how the last lot fermented so it should have the same end result.

 

[BigDaveK]

Again, the hydrometer measures density not sugar content. It might be close, it might not. SG is only one metric I consider when adding sugar.

 

[Peggy Billingsley]

Again, the hydrometer measures density not sugar content. It might be close, it might not. SG is only one metric I consider when adding sugar.

If you have a very thick must due to fruit pulp, how do you take that into account when you use the hydrometer

 

[ChuckD]

If you have a very thick must due to fruit pulp, how do you take that into account when you use the hydrometer

I push a strainer into the must and scoop some liquid into the testing jar. Of course no method measures the sugars still tied up in the fruit solids.

A refractometer works good in these situations because they only need a drop of must or fruit juice.

 

[BigDaveK]

If you have a very thick must due to fruit pulp, how do you take that into account when you use the hydrometer

I know that problem very well. I've had a few that were like applesauce, one that like a porridge.
I have a couple ideas:

I've lined a bucket with a brew bag, removing liquid for a measurement between the bag and the bucket, the bag acting like a filter.

I've used a strainer like @ChuckD mentioned. If the must isn't too thick it works great. (Sanitized first, of course!)

Thick must is only an issue for the first few days and of course it's important to know where you're starting. What I've been doing lately is researching my ingredients to find out how much sugar they approximately have. And then, also as @ChuckD suggested, I test with a refractometer to get the Brix. (An inexpensive device and it comes in handy.) If my research and the Brix are close, I go with that as a starting point and then add sugar. One pound of sugar raises 1 gallon about .040 approximately. I have had a couple wines where I ignored the SG and Brix because I knew my ingredients didn't have anywhere near that much sugar.

As a reminder the hydrometer and refractometer don't measure sugar content - the hydrometer measures density and the refractomter measures refractive index. Sugar is responsible for the measurement in many/most ingredients but not all. Other things can affect the reading. That's why I research my ingredients - plus it's interesting and I'm having fun.

 

[Rice_Guy]

If you have a very thick must due to fruit pulp, how do you take that into account when you use the hydrometer

The gravity scale is linear, you can dilute the must 50% with distilled water then run a gravity. Original gravity is the fraction (ex. .059 without the “1”) multiplied by two. This is mainly useful with honey or concentrate or syrups