Read Time: 10 Minutes
Level: Apprentice
When I silk temper, I usually grate the silk (to have very fine flakes), keep it in my room with an AC (temp is generally 20°C/68 F), and once the chocolate temp has reached 34°C/93.2 F I add the silk inside and stir, so the silk is still "cold". Sometimes when I break a piece of chocolate, I see white spots inside which I think is little pieces of silk which hasn't melt (although I stir for like 1min and let it set for another 1min before molding). Am I right or it's something else I see ? Maybe I should let the silk warm a little bit without melting (of course) and add it to the chocolate?
Those white spots you see are indeed the silk. You have a few rather subtle things going on. The feel I get is that you don’t really know what is going on and so you can’t troubleshoot it yourself. Let’s go through my mental process of what I just read and how you could have solved this yourself.
First off your main issue is that you are adding the silk to your chocolate at the wrong temperature. 34 C/93.2 F is too low. It should be 35 C/95 F. That may not sound like a lot but the key here is that you need to add the silk at a temperature that when the whole mass equilibrates, the final temperature will melt the silk. Since we make silk at 92.5 F, that is your final temperature goal.
If you had added the silk at 34 C/95 F, and you are adding it at the right amount (0.5 – 1%) then the final temperature should be 33.6 C / 92.5 F and at that temperature the silk will melt.
Aside from adding the silk at the wrong temperature, it does not appear you checked the temperature of the chocolate before you molded it. I can guarantee it was under 33.6 C / 92.5 F by the fact that you have unmelted silk in your bar. I suspect you glossed over that I say the resulting temperature should be 33.6 C / 92.5 F and I’ll own that I didn’t tell you why it should be there. It is there so you melt the silk.
I give pretty specific directions that account for most of these variables and I could give even more detailed directions but much of the point of using silk is that it is easy and not fussy…but you still need to know what is going on and account for your own conditions.
Silk isn’t magic. You can’t just go through the motions (grate some in, stir a minute, wait a minute, pour up) and expect it to work 100% of the time if you are not paying attention to the details.
There is a phrase I really love by Constantin Brancusi.
“Simplicity is Complexity Resolved”
The truth of the matter is the tempering in any fashion is complex. Armed with knowledge, it becomes simple. So let’s dig into the nitty gritty of some of the complexities and show how it really is pretty simple.
I’m going to start with the simplest directions that really tell you everything you need to know but that are also not incredibly helpful…but also are not wrong.
Add as much or little silk to your melted chocolate so that the final pour up temperature has melted the silk but not untampered it and the resulting bars are perfectly tempered and show no unmelted silk.
That is not super helpful as I’ve given you no temperatures. I’ve left it up to you to know that that final temperature should be 33.6 C / 92.5 F. I’ve also left it to you whether to add the silk in a solid form or in its opaque thickened form. I’ve also not told you how much to add. Dark chocolates require very little silk. 0.5% In my experience is more than enough. Milk chocolates depending upon the recipe can take 1.5%. If you are doing a high coconut oil milk chocolate you might need upwards to 5%. If you notice, that is an order of magnitude difference in the amount of silk you could use.
If you are grating your silk it is literally impossible for me to tell you what temperature your chocolate needs to be unless I also tell you what temperature your silk has to be. Without running through the literal thermal balance equations (which I might do, I’m undecided as I write this) I can’t tell you those temperatures. But what I can tell you, as it is just pure logic, is this.
The more silk you add, assuming it is in solid form and therefore colder than your chocolate, the warmer your chocolate needs to be so that when the whole chocolate/silk mixtures comes to a stable temperature (the silk warms up and cools the chocolate in the process), that temperature is 33.6 C / 92.5 F.
And we can follow that up with more.
The colder your silk is, the warmer your chocolate needs to be so that when the whole chocolate/silk mixtures comes to a stable temperature, that temperature is 33.6 C / 92.5 F.
There is nothing surprising there. It is no different from adding ice to water with the goal of having an icy drink at the end. The hotter the water, the more ice you need or the colder the ice needs to be.
What this might look like is that if you are adding 2% silk at 15 C/59 F, your chocolate might need to be 36 C/97 F for the final temperature to be 33.6 C / 92.5 F. (note, I’m making these numbers up as an example, I am NOT saying your chocolate has to be at 97F if you are adding 2% silk at 59 F)
But there are a couple places you can run afoul even following those directions. Let me give you an outer case example. Either through thermal balance calculations or because you have just tested it, you have determined that when adding 5% silk at 10C/50 F your chocolate must be 40 C/ 104 F. You, having done your measuring and temperature checking boldly go off and temper your chocolate….and it blooms horribly. What the hell went wrong? In short you forgot that silk is a special form of Type V (V’ pronounced 5 prime) tempered cocoa butter and if you heat it up too much while equilibrating you can destroy it. How hot Is too hot? That is the rub. I don’t know. There are just too many variables. That pat and unhelpful answer is that if your chocolate bloomed, it was probably too hot.
Basically, this is a version of the Spiderman/Uncle Ben mantra. With great power comes great responsibility.
Silk is powerful…but you need to know how to use it….at least if you go off script a little, i.e. changing percentages wildly, not checking your pour temperature, having your silk extra cold.
If you do need to go off script and just are not up for the trial and error and/or the thermal calculations, what do you do? The easiest way is just get rid of all the temperature variables. And really, when I first started talking about silk, that was the fool proof advice and, well, it is fool proof.
Just bring your chocolate to 33.6 C / 92.5 F and keep your silk at 33.6 C / 92.5 F and it no longer matters how much you add. Easy peasy lemon squeezy….but it is arguably a little more fussy and people were asking for us to sell it, so I worked out the out how to do it with solidified silk. We went off script as it were..
That is it really. You can either keep everything one temperature or give it a little extra thought, understand what is going on and adjust accordingly if you want the convenience of being able to grate it.
It is also worth mentioning that taking your solidified silk and melting it can be super tricky if you don’t have a sous vide. It is really easy to fully melt instead of just softening it. Melted (as opposed to opaque and softened silk with a mayo texture) silk is just cocoa butter and is basically ruined as far as tempering goes.
EDIT: So I originally posted the stuff below and both received a reply and realized I made a mistake, so I need to take it back. Those calculations don’t work. For one, I over complicated them (see below). For another I made an error double weighting each component. Don’t worry if that doesn’t make sense. What really matters is that they don’t work even with the equations fixed because there is a major component I left out which accounts for the temperature drop, and that is the energy needed to melt the Silk. State changes (melting for instance) take more energy than you would expect. And at the end of the day, that gets to be a messy calculation as you need to get into standard units, heats of fusion, and stuff like that and by the end, it is easier just to bench test it. Test, record, evaluate, adjust, rinse and repeat. In short interate.
Lastly, two people have told me I needed to tell you to use Kelvin (a version of Celsius often used in this kind of calculation), and I 100% stand by the fact that C or F works in this limited case…well, if it had worked in the first place. What I mean by that is once corrected, whether I use Kelvin, Celsius or Fahrenheit, the example below comes to 94.7 F. And for the curious, the correct formulation (that doesn’t work because of the Heat of Fusion) is:
(C x T1 )+ (S x T2) = T3 * (C + S)
Carry on.
Ok, I decided to continue on with calculations.
For those that want to run the calculations, it really is pretty simple if you are algebra fluent and accept it is a simplified version of some more complicated thermodynamic equations that use specific heat capacities of all the individual ingredients, which for our purposes are just not needed.
If you are not algebra fluent, I probably would not bother. If you are, then you can use this equation.· C = Amount of Chocolate (Imperial or Metric)
· T1 = Temperature of Chocolate (same, F or C is ok)
· S = Amount of Silk (in the same units as the Chocolate)
· T2 = Temperature of Silk (in the same units as T1)
· T3 = Final Temperature of the Chocolate and Silk together (it will be in whatever you choose above)
( C x T1 ) x (C / (C + S) + ( S x T2 ) x (S / (C + S) = T3 x (C + S)
In short, the percent contribution of each part times its temperature, added together, will then tell you the final temperature. There are tons of ways to rearrange that equation algebraically but I’m not going to run you through it as the chances are it will just get too confusing.
But I will give you and example using 1 kg of chocolate (1000 grams) at 95 F and 1 % silk (10 grams) at 65 F, the temperature and percent I use and recommend).
(1000 x 95) x (1000 / (1000 + 10) + (10 x 65) x (10 / 1000 + 10) = T3 x (1000 + 10)
(95000 x 1000 / 1010) + (650 x 10 / 1010) = T3 x 1010
94059 + 6.4 = T3 x 1010
94065.4 / 1010 = T3
T3 = 93.1 F
And by the time you have mixed in the silk in a room cooler than 93.1 F, your chocolate will have further cooled to around the target temperature of 92.5 F. And that is why I recommend mixing in 1% at 95 F to give you a working temperature of 92.5 F and why if you room is significantly warmer or cooler, you might not hit 92.5 F. The same goes for adding in your cold silk when your chocolate is 93.2 F (the original question). You can see it is going to end up around 91 F which is too cool to melt the silk you grated in.