I ordered 70% dark chocolate from an online store but they sent me 99% chocolate. I've been trying to find measurements on the Internet on how to turn it into 70% dark chocolate, but most of the sites don't say a specific amount. As Christmas comes closer, I'm starting to panic.
Any help would be much appreciated.
If it's any help the precise conversion for any two concentrations is
C1xV1 = C2xV2
where C = concentratiion and V = volume or weight.
So, for 1 unit of 70% from 99%:
70 x 1 = 99 x V2
rearrange to make V2 the subject:
V2 = 70/99 = 0.707
So, if you took .707 g or 0.707 oz of 99% and added it to something to make up to 1 g or 1 oz, technically you would have 70%. However, adding sugar or milk won't make you chocolate that will set like a block. For that you need to add cocoa butter and likely some sugar. How much sugar would depend on the style of block you aim to make.
If you take your favourite brand of 70% chocolate and look at the dietary information on the back (assuming you are in a country with this information provided), then it will tell you how much of your 70% block is sugar, though if you are in the USA, you may need to do a little conversion from servings to percent.
The popular brand Lindt, has, according to this website 12 g sugar per 40 g serving (4 squares) in their 70% block; so 12/40 = 30%, so almost all of the remaining 30% is sugar. I don't know how much of this is natural sugars present in the cocoa to start with. However, if it is any help, the same site has the 90% as 3 g sugar/40 g = 7.5%, so less than the 10% you might expect if the sugar makes up all the additional mass.
Cook's Illustrated says you can replace 1 ounce bittersweet/semisweet (70%) chocolate with 2/3 ounce unsweetened (99-100%) chocolate + 2 teaspoons of sugar.
However, they note this will only work well for baked good like brownies. Unsweetened chocolate has more starch than sweet chocolate so it may not work as well for a cake.
Chocolate "percentages" (for "pure" dark chocolate, anyway) work as pretty much as follows:
70% chocolate is 70% cocoa, 30% sugar, and (yes, more than 100% total) a percentage of cacao butter, at least if it's the real thing.
For the real thing, the fat ratio is fairly consistent, though it may vary slightly with the raw ingredients. Two examples from a chocholic's stash.
Callebaut 70/30/38
Schokinag 75/25/40
Both are listing cacao solids / sugar / fat percentage, where cacao solids and sugar add to 100% for "chocolate percentage", and the fat relation to cacao solids is 53-54% for those examples (40/75 and 38/70)
So, assuming the cacao butter has not largely been siphoned off to the cosmetics industry, the weight of your 99% chocolate is actually 152-153% of the weight of the cacao solids in it. Further math says the cacao solids are about 65% of the combined cacao solids and cocoa butter mass, pretty much.
So if you have 100 grams of 99% chocolate, it's got 64-65 grams of cacao solids, and 26-27 grams of sugar added to that would make 126-7 grams of 70% chocolate.
It's mostly confusing because of the special way the chocolate industry uses "percentage" which is not intuitive.
You can't just add sugar to chocolate and change the % of chocolate that way. If you have a melanger and want to integrate new suger you can, but it's not ideal, and the consistency won't be the same. Also keep in mind that the % chocolate is going to be a mix of solids and cocoa butter, and there's no way to know how much of each was used. For one thing, different beans have different percentages of cocoa butter (usually just above 50%), and also because most manufacturers add additional cocoa butter to their chocolate. Some also add lecithin and other ingredients. The best way to add sugar to this would be to find a chocolate that is much lower and combine the two and then re-temper it. You can then very easily calculate how much of the second chocolate to use based on what percent chocolate you're using to add sugar to the final blend.
