Hi everyone. I know I’ve been a little a lax with getting Ask the Alchemist articles out weekly since having a hole drilled in my head a couple months ago. Really the reason is two fold. 1) I had a hole put in my head and I lost a bit of my rhythm and 2) out of what I guess is consideration people have not been sending in questions. So, please, if you have questions, please send them in. I’m back in fighting form and raring to answer your questions. Before I get to that I have a few announcements.

There is the Roasting Seminar 2019 coming up in September of which there are a few slots open still. In it you will learn all about how to develop and control flavors during a roast. We focus on drum roasting only and you will hands on experience roasting on our antique 1905 Royal #5 roaster. We dive deep into roasting theory, practice and roaster use.

Speaking of roasting, Behmor has come out with their new AB (All Black) Behmor 1600 which features a higher drum speed for better convection (psst, I cover why convection is a great in the drum roasting seminar above).

And while we are at it, the Behmor Brazen is also back in stock. It is the best Brewer on the mark in my opinion for coffee and the only one I know that works on Brewing Cocoa.

Last year I visited for the 1st annual Bean to Bar festival in Sao Paulo Brazil. While there I had the honor to meet so many amazing people. Chocolate makers, growers and farmers. One such person was Pedro Neto of Lajedo do Ouro. He has an incredibly beautiful farm located in the northwest corner of Brazil in the Ihious Region of Bahia. He was also gracious enough to host me for the night during our tours. His farm is very organized and well kept with varietals as segregated as possible. We have these two offerings from his farm.

Brazil Catongo 2019 - First and foremost it is an albino forastero called Catongo. That genetic mutation makes the beans white and has on again off again been mistaken for porcelano and the chocolate is often mistaken for milk chocolate. If you are adventurous and like the unique do not let the bean get away.

Brazil Lajedo do Ouro 2019 This is a blend of varietal from the above farm. There is a distinct citrus pith and cured tobacco. The chocolate level is moderate and has a slight iron rich tang that comes along. It is a moderate Brazil nut flavor (no relation to the country) and hints of dried prune in the finish. Again, this is a unique bean and I only have a little to provide. Sorry, no wholesale for this one.

Ok, back to this week’s hybrid ATA. I recently had a great conversation with someone by email and thought it worth sharing. And that brings up a good point. You are always welcome to write me directly (well through the website interface) and I make it a point to answer all emails and questions. You are not imposing. It is why I’m here and I love talking to you all.

I use my Sous Vide for so many things and am planning on making silk. My question is however have you tempered chocolate using a sous vide. I have seen people do it on the Bon Appétit YouTube channel (The tempering starts at 23:00 ) it looks easier than making silk but seems you could lose a high amount of chocolate with using multiple containers. Any tips or thoughts.

I've tried tempering chocolate with a sous vide and hated it. It took so long, was a mess and frankly didn't work well. The right way to use a sous vide for tempering is to make silk and use it. Silk is just so perfect IMO. You set it for 24 hours and then use it for as long as you need.

What did you think of the video?

That it is a LOT of hands on work, massaging constantly, and only works for small amounts. And granted she heated the tops to soften them, there is really nothing actually proving her initial chocolate was tempered. I'd be really skeptical with only going to 84 and going up to 90. It should be more like 80-82 and 88 F.

She so needs to have a course in tempering or just be introduced to silk. Grate 1% in at 95 F and she would be done. It would also have allowed her to dip the bars instead of trying to pipe them.

I worked in the food service industry for decades. I used a sous-vide back in the day and I still use one today. The concept that what is being heated or cooked won’t take a transfer of heat fully and thoroughly is a popular misconception. I use mine to bring steaks to temp before grilling and I make salt rising bread starter, I even thaw out frozen chicken before cooking. So from solids to liquids frozen to room temperature as long as you don’t have a large amounts of air to insulate the food it works.

The Science; Sous-vide means “under vacuum” in French. In physics, the second law of thermodynamics says that heat flows naturally from an object at a higher temperature to an object at a lower temperature (in this case from water to chocolate), and heat doesn’t flow in the opposite direction of its own accord. People make the mistake of using the device without a vacuum and fail most of the time. Liquids work well in a jar, melting solids in a jar will work but takes a longer time.

I too use a sous vide often in my non-chocolate cooking endeavors. As a chemist I'm quite familiar with the 2nd law. The main issue with sous vide still is that heat transfer inside the food is all conduction which means it is really slow. Without convection, the time to equilibrate is longer than I ever find practical for chocolate tempering. It is rather like fitting a square peg in a round hole. People want it to work so bad they convince themselves it is easier when really it isn't.

To that end, what is the appeal of making the bag technique work? I really don't get it when there are other more efficient methods.

For a guide to measure my attempt by, how long does it take you to temper chocolate using a sous-vide and if you don’t use a bag how do you do it?

It was well over an hour. I was doing a kg. I very much disliked it as I had no way to know truly if it was at temperature. The bag reflects too much and gives odd measurements for IR. I also got lots of bloom streaks due to the edge of the bag and I found it a huge waste of bags when after the first time I had to seal it again because the temperature was not right. The whole methods is just fraught with problems given my desire for accuracy, approachable and efficiency. Overall I found it just too fussy for the supposed advantage.

I also tried it in a jar and it was HOURS due to no heat penetration. The center was still not at temperature after 4 hours. Fat insulates really well. Just ask whales and seals.

I love it for making silk because it is hands off and I just let it set for 24 hours. In that case you are giving it the time to penetrate and the slow methodical heat penetration gives the cocoa butter the time to form into a really stable and strong crystal matrix.

Sorry one more question if it is not an imposition. What is the difference between how you temper chocolate and how you make silk in the heating times etc?

I'm here for questions. No worries.

Silk is isothermal for 24 hours at 92.5 F. Chocolate you have to raise and lower. 100 -> 80 -> 88 F as quick as you can.

Okay now I am starting to understand your trepidation. Silk is set it and forget it. During the first 30 to 50 minutes you need fast temperature changes and so you have to massage the packet to get them to take the temp change in the required time. What happens if you don’t make the temp changes as fast? What would happen if someone drops by and you let stage one or two go for say 2 hours? Will it fail completely and need a reboot or could you just continue from that point?

It probably won't hurt anything to allow a slow temperature change. It just uses up time and it seems we are all running around with never quite as much time as we need. She actually had the right idea in the video tossing in ice although I would personally have used two different water baths and probably not ice but cool water. And really that goes for any stage. After it has thickened a bit at 80-82 F, you can bring it back up to 88 F and take as long as you want.

There is a big caveat though. If by chance the particular chocolate you have needs 87.5 F to be stable and you set it at 88 F then the longer it sets at 88 f the greater the chance of failure. In classic tempering taking it to 88 F is ok because you are molding up immediately and stopping the breakdown. Not so in a 2-4 hour sous vide session. And as I write this out the same goes for the initial stage too. If the chocolate only needs 81 F and you set your temperature to 80 you might come back to solid chocolate and while not horrible it just makes life extra difficult since heat transfer really slows down in a solid.

Tempering isn't 100% about the temperature. It is a time/temperature relationship that most of the time you circumvent by eliminating the time variable when you work quickly. But adding it back with a sous vide the whole thing becomes more complicated and unstable instead of easier, which was the presumed goal. Add to that not being able to quickly test temper since you have to open two bags, the whole thing turns into a black box system that is constantly fighting you even if you do have the patience of a monk.

That all said, I can see a use for a sous vide if you are in a kitchen environment and want to hold a silk batch at 92.5 F while you decorate or something. Having a sous vide controlled water bath is handy and because you are using Silk, you know the 92.5 F temperature and not relying on hoping you are in the nebulous 87-89 F range of classic tempering.