Tempering machine advice

Hello :)

We are a small handmade raw chocolate business ( www.liefje.com.au )in Melbourne Australia,looking to transition from tank melting and stone-top tempering by hand to fully automated or semi-automated tempering.

We make slim 55gram bars of couverture raw chocolate in polycarbonate moulds. On the tempering front the 'raw' part just means we need to remain under 42 degrees celsius at all times, which is probably just a matter of setting the temperature on any device (?).

Looking through past forums we found Clay's detailed advice to Stu Jordan which led us to the Selmi One as an option. The capacity is small at 10kg, but it appears we could temper 3 batches in one day, which would be ample and the built in volumetric dispenser and vibrating table would be ideal.

The challenge for us is that we're making bars with nut chips and cacao nibs mixed into the chocolate itself (think Toblerone-style but beautiful ingredients). Is there a tempering machine that can accommodate 'bits'?

We're baby artisans finding we need to increase capacity to meet demand. Any/all advice would be very welcome.

Thank you,

Nikki.

Nikki -

First off, why 42C? Most of the people I know who are working in the raw world here in the US use 47C (118F) as the max temperature. 42 is only 107F and that may not be high enough to thoroughly (and quickly) melt out crystals that have been formed in the couverture you are using (even if it is untempered).

Continuous tempering machines (Selmi, FBM) may not be the right answer for you as they work on the difference between a melting temperature and a working temperature. If your max working temp is 42C then you might not have enough temperature differential to form crystals - especially if the room you're working in is about 20-22C. I would certainly run tests through a Color to make sure before buying one.

You are also mistaken about the way continuous temperers operate - they do not work in batches. The hourly throughput of a continuous tempering machine is between 3-5x the bowl capacity, assuming that you can keep the working bowl "topped up" as you work. Thus, a 10kg machine is capable of producing 30-50kg of tempered chocolate per hour, not 30kg per day.

From experience, I can tell you that most continuous tempering machines are very bad at working with chocolate that has a higher viscosity than commercial couverture chocolate. This is because of the geometry of the auger in the tempering pipe. If the auger has a thin core and wide wings then it's going to be even more difficult to temper the chocolate properly - you will get uneven crystallization and it will be difficult to keep the tempering cycle intact during the working day especially when you are using the depositor. I've been working with FBM to address some of these issues for bean-to-bar chocolate makers and it took us a while to come up with the changes to the basic machines to make it work (it helps - a lot - if you can adjust the speed of the auger).

As for inclusions. The limit for continuous tempering machines (Selmi, FBM, whoever) is going to be pieces that are no more than 3-4mm in their widest point, and somewhere between 10-25% by weight. If you need larger pieces than this, or more pieces by weight, you're going to need to find another technique to fill the molds as the depositor is likely to clog easily.

Hello Clay,

Thank you for your detailed reply to our cry for help. Much appreciated.

We're working with 42C as the max working temperature as this is the guide we have been given by the raw chocolate experts we have learned the craft of raw chocolate making from. People like Amy Levin (ooosha.co.uk).

We have now grasped how a continuous-tempering machine works - thanks to a chat yesterday with the importer of Selmi in Australia. As we understand it, we would continue to work with a melting tank, adding 10kg of melted chocolate at 42C to the Selmi hopper to begin the tempering process, topping up as needed through the day.

The importer tells me there is an Australian raw chocolate maker working with the Selmi, but we don't know what max temperature they are working with. I will ask. Thank you for that advice.

On the inclusions front, after learning a little about the tempering devices,we have accepted that we will probably need to 'sprinkle' the bits like nuts and cacao nibs (they are under 3mm but the Selmi which can accommodate inclusions is the New Plus X which, at A$25,000, is beyond our budget). That's OK as the vibrating table will ensure the inclusions sink into the chocolate - whereas hand-banging the moulds (as we do at present) doesn't sink them in sufficiently.

If we find we need to stay under 42C to qualify as truly 'raw' chocolate by European and Australian standards, what would be your suggested method to automate or at least semi-automate the tempering process? We can only stone-temper so much by hand in a day! As we make the couverture from raw cacao butter and raw cacao powder a process that relies on the seeding method isn't really an option for us.

Thanks a million for sharing your knowledge and expertise with us.

Clay,

Could you please expand on the point about "...as they work on the difference between a melting temperature and a working temperature. If your max working temp is 42C then you might not have enough temperature differential to form crystals...."

Do these machines not 'subcool' the chocolate to trigger crystal formation and then heat back to working temperature? Or do they simply depend upon the temperature difference between the melt and the working temperature? Could agitation be added to the auger to trigger morecrystallization?

I have a similar interest in low temperature operations, not from a 'raw' perspective, but from a kosher perspective. If you keep your equipment below a certain temperature (which varies by supervision authority, in the range of 108-120F) then kosher supervision becomes easier because you are no longer considered to be 'cooking'.

Thanks

Jon

Jonathan:

The majority of continuous tempering machines employ 2 temperatures. They do not cool below a certain point and then warm slightly. There are some 3-zone machines.

I have attached five pages from a draft of a manual I am working on for FBM that describes how continuous tempering works in their machines. It makes reference to specific FBM products so that might be a little confusing to people who don't know the product line. In general the process is the same for all of the continuous tempering machines in this class. This is just a draft and just a few of the pages, and in reading through it I can see several typos and things I want to change that aren't as clear as they need to be.

The scraping of the auger against the interior of the tempering pipe provides the mixing force, so there is agitation. FBM's auger geometry is designed to maximize crystal formation and mixing; the geometry of the augers in other systems don't appear - to me - to be as well designed.

As for the temperature differential thing part of it has to do with the amount of time the process takes. In a Chocovision machine, for example, it might take 30 minutes for the chocolate to cool from 115F to 89F. That's a lot of time for crystal formation. In a continuous tempering machine like the ones from FBM the process happens in well under 20 seconds. In the larger FBM machines (the Unica for example) you can control the speed of the auger which means you can increase the dwell time in the tempering pipe and this allows you to work colder - there's more time for proper crystal formation and, importantly, spreading the crystals through the chocolate.

In my experience the temperatures you need to melt the chocolate to are in the 45-50C range (max 122F). There are some chocolates that need to be heated up much higher and some that don't need to be heated up as much. It all depends on the physical properties of the chocolate. The chocolate is going to dictate the temperatures.

Here in the US among the raw chocolate makers I have worked with, 47.7C (118F) is the accepted max temperature. It's important to note that there are no definitions written into food law - anywhere in the world that I am aware of - that set a standard for what raw is and raw isn't. It's also not clear (to me) that it's a single temperature. Lettuces are far more delicate than nuts and probably shouldn't be subject to anything over 40C for any length of time.

Where are you getting the butter and powder from? Have you personally inspected the production processes? Can you guarantee that the butter and powder are never subjected to temps above 42C? How about the temps of the fermentation pile? They naturally want to get to 50-52C to do the best fermentation. Drying? In full sun the temps on the drying pad can easily reach 60C.

What I (and others) think you need to be more worried about is the microbial load because there has been no kill step (this is one aspect of roasting). Make sure you do a plate test!

On the continuous tempering machine front:

FBM machines from the Prima (7kg working bowl and a list price of under 7,000) on up can handle 3mm inclusions and all machines with working bowls under 45kg come with a vibrating table, measured depositor, and a removable and reversible auger as standard equipment. The FBM Compatta has a 12kg working bowl with the same standard features as the Prima and has a list price of under 10,000 before a ChocolateLife member discount of 10%. (Not including shipping from Italy and any local customs fees).

Thanks for posting your paper.

I am curious about how temperatures above the melting point of the cocoa butter factor in. For 'simple' compounds, once you have heated the material above the melting point there can be no solid phase left. If you have water above 0C with ice floating in it, then the ice itself is still at 0C and time delay for its melting is due to the limits of thermal conductivity.

If I have a stirred fluid bath of chocolate at say 100F, with no macroscopic chunks, then can crystals of cocoa butter still be present? (This is not a rhetorical question; I've been assuming not, but realize that I don't know...I know that the crystallization seems to take time _after_ the chocolate has cooled to the required temperature, so I could imagine that after the chocolate has been heated there is a time delay before crystalline order is lost.)

If chocolate is not heated enough to fully dissolve all of the crystals, then is the only risk one of overtempering? Or can you get the wrong crystal forms?

Thanks again.

Jon

Thank you Clay,

Your advice has been a big help. We will look into the cacao production process in more depth and request a plate test. We'll also test drive potential tempering machines to see if they work effectively with our low temperatures.

Nikki.