Estimating PPG for fruit juice

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hezagenius

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My ultimate goal is to estimate how many PPG I can expect from fruit juices like apple, grape, orange, etc. I have not been able to find any data on this. Based on the nutritional data and SG, I can figure out how many grams of sugar are in 1# of juice. What I am wondering is can I estimate the PPG of these juices by scaling the PPG of dextrose?

Example:
According to Palmer, 1# dextrose contributes 46 PPG. I’ve seen other numbers ranging from 37-46 PPG but let’s assume 46 PPG is the correct number.

1# ~= 453g so 1# dextrose ~= 453g dextrose

If 1# dextrose contributes 46 PPG, then it looks like we can infer that, for dextrose, PPG ~= 10% * mass in grams (0.1 * 453 = 45.3 ~= 46).

If 1# of a fruit juice contains 50g sugar and we assume the sugar in the juice is equally as fermentable as dextrose (I don’t know how accurate that assumption is), then it seems to me that the 1# would contribute apprpoximately 0.1 * 50 = 5 PPG.

Does this seem like a good way to estimate PPG?

Is the sugar in fruit juice as fermentable as dextrose?
 
My ultimate goal is to estimate how many PPG I can expect from fruit juices like apple, grape, orange, etc. I have not been able to find any data on this. Based on the nutritional data and SG, I can figure out how many grams of sugar are in 1# of juice. What I am wondering is can I estimate the PPG of these juices by scaling the PPG of dextrose?

Example:
According to Palmer, 1# dextrose contributes 46 PPG. I’ve seen other numbers ranging from 37-46 PPG but let’s assume 46 PPG is the correct number.

1# ~= 453g so 1# dextrose ~= 453g dextrose

If 1# dextrose contributes 46 PPG, then it looks like we can infer that, for dextrose, PPG ~= 10% * mass in grams (0.1 * 453 = 45.3 ~= 46).

If 1# of a fruit juice contains 50g sugar and we assume the sugar in the juice is equally as fermentable as dextrose (I don’t know how accurate that assumption is), then it seems to me that the 1# would contribute apprpoximately 0.1 * 50 = 5 PPG.

Does this seem like a good way to estimate PPG?

Is the sugar in fruit juice as fermentable as dextrose?
Hi. Yes, but unless another type sugar was added to the juice, it should be fructose, which I believe has a slightly lower ppg than dextrose/sucrose, so your formula might be a bit high. Here's a nifty article with tables about sugars in BYO. Ed
:mug:
 
Measure your juice with a hydrometer - that'll tell you for sure how much sugar is in it... nutritional labels tend to incorporate coarse rounding.

I did roughly the same calculations as you when making apple wine from store bought juice, apple juice concentrate, and dextrose.

Also if you have a brix (or plato) hydrometer that the reading is expressed in w/w %. So a 12 plato solution has 12g of sucrose per 100g of solution. You can also do a reasonably accurate conversion of SG to plato/brix. Depends on your accuracy requirements but its close enough for many applications.

There is a difference in density of difference sugars... but unless you know the ratio of them it's going to be difficult to give an exact number, but for a rough calculation you could assume its all dextrose.
 
There is a difference in density of difference sugars... but unless you know the ratio of them it's going to be difficult to give an exact number, but for a rough calculation you could assume its all dextrose.

Actually the densities of the sugars are quite similar but what is even more striking is that the densities of solutions of the same w/w are amazingly similar. This extends not only through the mono, di and trisachharides we usually concern ourselves with but even into the soluble starches. Thus the advice to get a specific gravity reading and convert it to Plato is sound as that will give you the grams of extract per 100 grams of solution. You need not concern yourself with whether 1 gram of extract is actually 1/2 gram of glucose and 1/2 gram of fructose bound up in a sucrose molecule or 1/2 of each hydrolyzed from 1 gram of sucrose or 1 gram of maltose or 1 gram of glucose etc. One gram of extract gives very close to the same amount of alcohol, CO2 and biomass.
 
Thanks for the help. I measured a Brix value of about 10.5 for OJ so that equates to ~48g per pound or roughly 4.8 PPG compared to ~5.1 PPG using the SG and the grams of sugar per serving on the label.
 
Thanks for the help. I measured a Brix value of about 10.5 for OJ so that equates to ~48g per pound or roughly 4.8 PPG compared to ~5.1 PPG using the SG and the grams of sugar per serving on the label.

If its 10.5 °P then its specific gravity is about 1.0421 and its density 0.998203 times that or 1042.3 grams per liter of which 10.5% equal to 109.22 grams is 'extract'. A gallon is 3.785 L so a gallon contains 413.4 grams equal to 413.4/454 = 0.991 ppg. The ppppg then equals 42.1/0.991 = 42.5.

Five pounds of sugar in a gallon of water is approximately
100*5/(5 + 8.3) = 37.6 °P with specific gravity of 1.167
 
I'd be a little wary of hydrometer readings made on OJ because of the pulp.

I used SG to calculate the volume of a pound of OJ.

If its 10.5 °P then its specific gravity is about 1.0421 and its density 0.998203 times that or 1042.3 grams per liter of which 10.5% equal to 109.22 grams is 'extract'. A gallon is 3.785 L so a gallon contains 413.4 grams equal to 413.4/454 = 0.991 ppg. The ppppg then equals 42.1/0.991 = 42.5.

Five pounds of sugar in a gallon of water is approximately
100*5/(5 + 8.3) = 37.6 °P with specific gravity of 1.167

I'm interested in sugar per pound of OJ, not per gallon of OJ.
1# of OJ was about 14.7 liquid oz (based on the SG) so a gallon is approximately 8.7#
8.7 * 4.8 PPG ~= 42 points per gallon of OJ per gallon of wort

I'm making a recipe calculator and using pounds as the input unit so I think I am still good using the 4.8 points per pound of OJ per gallon of wort.

[edited for clarification]
 
Plato/Brix is approximately equal to 1000*(SG-1) / 4... so an SG of 1.042 is equal to 42/4=10.5 Brix/Plato.
 
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