Ask the Alchemist #145

I tried different roast profiles ranging from 250-325F 4-28 minutes. I am trying not waste many beans by putting only a cup full of beans in at a time. I realize that the roast wouldn't be representative of a full oven, but my goal was to try to find a good dwell temperature and time. Once I found my dwell time and temp I would increase total roast time to account for the increased ramp time of a loaded oven. Do you think this approach is acceptable or should I always experiment with what will be my typical roasting weight?

Roasting. Some of you will love this. Some of you will hate it. Some will eat it up and suddenly everything will make sense. Some will fall into despair that you will never get it and you are doomed to wander the wasteland of uncontrolled roasting. I really hope the former outweigh the later.

I understand your reasoning about roasting just a cup. Unfortunately, the reality is that to effectively use that technique you will probably end up using more beans in the long run as you scale up. The reason is this. You learn best from an experiment by changing one variable at a time. Otherwise the permutations get too great and you can't tell really what effect your changes had. You are changing two (or possible three things) as you progress up in weight. Weight, time and temperature/profile. It's possible to glean information from this but it actually takes more runs and more cocoa unless you get lucky. I know you said your plan was to increase roast time. Experience tells me that won’t work. Fundamentally because by changing the time, you are changing the roast profile which means you are in the apples and oranges situation. They are not comparable. More on profiles in a little bit.

The main problem is that by roasting only a cup of beans, the data you get isn't transferable to a larger load expect to say you will know you will need some combination of more time and heat. But you already know that, right? In essence you used a cup of beans and have no more useful information that you did before. If your 1 cup of beans took 8 minutes at 325 F you have nowhere to go with that information if you try and roast 2 cups. It's not linear. It won't take 16 minutes @ 325 F, nor will it take 8 minutes at 650 F. It will be somewhere in the middle....which you already knew most likely.

On the other hand, if you roast 1 lb for 16 minutes @ 300 F, and determine they are under roasted, you have somewhere to go. You should either increase the roast temperature (my first choice) OR time. If 1 lb is still under roasted at 16 @ 350 F, then for your next roast you increase the temperature to 350 F for 16 minutes. If that is still under roasted, you can start to increase time as you don’t want the oven much hotter, generally speaking. In short, yes, it will take a few runs, but you will get useful data from the methodical approach.

So to directly answer your question, I think you should test roast the weight what you will be roasting in your standard batches. Here is what I hope is a good analogy.

You will never master baking a 2 lb loaf of artisan bread by baking 2 oz bread rolls. Rolls need a cooler temperature or you will burn them. And they need a shorter time. 350-400 for 10-12 minutes will do the trick. A 2 lb loaf could well take 60 minutes at 350 F. To compensate for that large mass, you can put it in at 500 F for 15 minutes. It won't burn since there is so much there that has to heat up and soak in. But you can't keep it there or is will burn. After 15 minutes, you turn it down to 425-450 for another 15-20 minutes and it continues to cook without burning the outside. Sounding a little familiar?

In short, you have to learn your over for a given batch size of beans. You have to actually load the oven enough so it's doing some work. And you have to find the sweet spot, batch size wise, for your oven. All ovens have a setting for 350 F. But they all don't apply the heat at the same rate. Some might take 5 minutes to get an empty oven up to temperature, and another might take 15 minutes because it is lower wattage or has less BTU/hr (electric vs gas). That right there is the crux why I don't and simply can't give people exact temperature 'profiles' to roast in an oven. We have zero knowledge that your oven matches my oven and without that, a temperature is useless.

I'm going to keep repeating this different ways. Let's say you need to go 1 mile in your car. 1 mile is well roasted beans. How am I to tell you (without an odometer) how long to push on the gas pedal to the floor when you only have a speedometer? I should make the note that we can't talk about partly pushing it down. We have to push it to the floor as that is how ovens work. They apply full power until they hit temperature, then turn off until the oven cools some amount below temperature. In short, I think you can see I can't give you that information.

My car might make it to 60 mph in 5 seconds. If that is the case I need somewhere around 55 seconds to go 1 mile. But if your takes 25 seconds, you clearly are going to take well over a minute total to get there. And without that exact data, and pulling out some algebra equations, I can't tell you how long it will take.

But let us assume we have that data for both cars. What can we predict if we hook up a 1 ton full trailer to the cars (i.e. roasting more beans). I think you can see that the answer is nothing at all. Maybe my car is light and can accelerate well under a light load but has no extra capacity so takes 60 seconds to get to speed under load. Yours on the other hand is huge and that is why it took so long to get to speed the first time. Yours, because it has plenty of extra capacity hardly notices the extra load and takes only an additional 5 seconds and you are up to speed in 30 seconds. Clearly yours will make the mile in just about the same time, whereas mine will take 50% longer.

At the end, what I am trying to get across is that AMBIENT oven temperature (i.e. the dial setting) is a terrible gauge to describe roasting profiles....but it is all we have!! By preference I would like to say this to describe a roasting profile.

For 6 lbs of beans, apply 2000 watts of power for 12 minutes. Then apply 1200 watts of power for 3 minutes. Finally, apply 1000 watts of power until the beans either smell done or the beans are at 265 F. Why? Because it is scalable! If you have 2 lbs of beans, then you need to apply 1000 watts for 12 minutes, 600 watts for 3 minutes and 500 watts until you hit 265 F. Half the beans, half the power. Because THAT is a roasting profile. Energy input in a given time. Not temperature settings.

And just so I don't skip the detail, that is for a well insulated system, neglecting heat loss. The reality (based off a given roaster's insulation - see, more variables again) is that I may need only 900 watts for the 2 lbs of beans in the first leg of the profile, or I might need 1100 watts. And how do you know which it is? NOW temperature comes into play. Because we are getting to how I roast day to day. For the above profile, for me, this is what is actually going on.

Apply enough energy so my surface bean temperature goes from room temperature to 210 F in 12 minutes. For MY ROASTER this is 2000 watts.

Turn down the energy input so the bean temperature goes to 245 F in 3 minutes. For my roaster this is 1200 watts.

Turn down the energy again so I reach final target temperature of 265 F (which I have predetermined by SMELL and TASTE of previous roasts) in 3 minutes.

That now is an honest to goodness roasting profile that anyone can take and apply to their own roasting situation and with any amount of beans. Assuming they have a way to control the power (energy input) of the roaster AND know the bean temperatures at different stages along the way. Without all three of those items, my profile is useless to you. Which is why I don’t offer them up as a matter of rote. It is also why I give the very generic ‘profiles’ I do give.

From my Roasting page:

In general, if you try oven roasting, you will start hot (350-400) for a short amount of time and slowly lower it to you target temperature (300-320 F). The more you are roasting, the higher your initial temperature can and has to be.

Remember, you want to roast the cocoa beans, not bake them. This is how this looks: Whole cocoa beans 375-400 5 minutes 350 5 minutes 325 5 minutes 300 until done. Look for the aroma of baking brownies and/or pops. Both are good indicators you are there.

I’ve tried the best I could to give something usable based on what I know and what the limitations are to oven roasting.

So, there. What does that get you? Hopefully a peak into my thought processes about roasting, profiles, what they are and what they are not. Hopefully there is a nugget or two in there on what you need to develop your own profiles, or at least an understanding the limitations of your tools (your oven). And why I’m not being obstinate about sharing my profiles. To rift off of A Few Good Men, “You want the truth? You can’t handle the truth!”. 

I’m not withholding the truth because you can’t handle it. Or maybe I am. I’m withholding it because in most of the cases out there, it’s useless information because you don’t have the background and equipment to use it.

This is my first concerted effort to get you the background so you can handle the truth.

Ask the Alchemist #144

I am using a sous vide cooker to regulate my temps but I have yet to be able to temper a chocolate (55% dark milk) without the same problem this gentleman photographed in his chocolate. Small dark dots clustered together.

http://seattlefoodgeek.com/2010/12/the-strange-effects-of-tempering-chocolate-with-a-sous-vide-machine/

I tried three different routines in my sous vide for tempering. All with temps going from 119 degrees to 81 to 87-90. Tried with constant mixing by hand on bag with short soak time (5 minutes at each stage), constant mixing with long time soaking between temps (20 minutes at each stage), and no mixing with long soaks (30 minutes at each stage). All the chocolate looks like in the link above. The funny thing is when I was done filling molds (all perfectly dry at room temperature and 25% humidity room) I took the extra and put in one of those solo cups and that chocolate had the least of the black spots.

I am at a loss. Not sure what could be going wrong. Any idea? I am experimenting with various levels of mixing and various soak times at each temperature but still getting the same effect.

It funny. I love the idea and tech of a sous vide. And there are some amazing looking circulating immersion heater that I think would allow you to make your own version of the EZTemper, ala water bath. But the same thing that makes it great for that application is (I think) the same item that is causing grief with tempering.

In short, kneading or no kneading, it is really hard to get an even distribution of thick material inside a bag. If you don’t believe me, try taking a cup of shortening (butter is ok but what a waste) put it In a bag, put a drop of food coloring in it, and then try and knead the color in evenly. Maybe you can do it, but I bet you end up using your eyes a lot. Working the areas that are uneven, etc. Doing it with your eyes closed you will end up with a whole bunch of rather attractive swirls I’m willing to wager.

The issue is that even though the water surrounding bag of chocolate is an even temperature, there is just no way that the chocolate is that temperature, 100% homogeneous, in the short amount of time you are giving it. That is the first thing that struck me with Scott the Seattle food geek. He was not kneading or mixing at all. It seemed to me he was expecting the system to become homogeneous nearly instantly. He mentioned holding the chocolate at a temperature for 2 minutes. Maybe, just maybe the temperature was even throughout the chocolate. I say it was for the sake of argument (I don’t believe it for an instant). What absolutely was not even throughout was the distribution of Type V crystals.

And that right there is the crux of the entire issue. See if you can follow.

We use temperature as a way to determine if the chocolate seed is evenly distributed because we are mixing chocolate of different temperature. We are stirring the entire time. When the temperature is the same throughout, we can be confident we have distributed the seed evenly. The key here is that what is important is the distribution, NOT the temperature. The temperature is just what me measure.

Now, to be clear, temperatures ARE important. The seed will be destroyed if it gets too hot. I’m just saying it isn’t the only thing that is important.

Wen I was In the lab, and we were mixing up water solutions, the rule of thumb was to invert and swirl them 10 times. That is a lot of mixing. Stirring with a stir plate often took 10 minutes. It too that long for particles to REALLY distribute well. Heck, it is why sous vide circulate. And why what is in that sealed bag in the sous vide can’t be even in 2 minutes – there is no circulation in the bag. If anything, it is inhibiting circulation.

To make a sous vide work for temperature I suspect you would need to hold each temperature for 60-120 minutes to be sure, hand kneading 6-8 times throughout. That seems like a lot of work for something that is supposed to be saving you work.

I want to swing back to both the referenced article and your own experience. In both cases the lower temperatures were the goal. He took his chocolate (in theory) to 84 F. You took yours to 81 F. His was clearly too warm and seed did not form. In your case, it may or may not have formed. But you ‘sin’ was that the temperature was your goal. And that is wrong. The goal is cooling until the chocolate starts to thicken. That is the indicator you are looking for that seed is formed. And for all I know, you did take it to that point and are just reporting the temperature.

The next problem is that he took it to 88 F for only 2 minutes with no mixing. The temperature (if it was true which I can’t believe with a 2 minute hold) is fine, but the lack of mixing means the seed (if it had been formed, which it was not) would not have been distributed evenly.

In your case you took it to 87-90. You pretty much have a no win situation. At 87, even with mixing (remember the colored shortening?) you most likely had cold spots where Type IV crystal were hanging out. Those lead to those spots you see. At 90, since this is milk chocolate, you are way too hot. So you had areas where no seed or crystals of any type existed. Hence the swirls and other spots.

In short, it looks to me you probably didn’t form seed. If you did form it, you either didn’t distribute it well, and/or had hot and cold spots because chocolate is thick compared to water and is damn hard to mix in a bag (corners are brutal).

How can you make it work? I’m honestly not sure. I’ve known a few people to get it to work and generally they take the slow approach. Each stage is 2-3 hours with periodic hand mixing.

At the end of the day, ‘fast sous vide’ which is what you are attempting is sort of an oxymoron. It’s just the wrong tool for the job in my mind.

Ask the Alchemist #143

Oops, I’m reading your post (ATA 142), and I think you misunderstood the question: it’s not a problem. It’s a GOOOOOOD thing that it’s thickening. This recipe results in beautiful magically thick and velvety drinking chocolate. The question is why?

What exactly is thickening it? I want to make sure I understand what’s happening so that when I instruct others to make their drinking chocolate this way I understand what the potential failures are.

I did indeed misunderstand the question. Seems like that pattern that has been established that I fell into is that people write with problems and not pure ‘why’ questions. I did what dislike. I read between the lines – and did it poorly. Which is why I really try and not to do it.

So, why?

The short not helpful answer is that you are creating an emulsion. In layman’s terms this means that the water molecules are being surrounded by fat molecules. When this happens that water can’t act like water. It acts more like a solid. Hence thickness. With enough water, it can also go the other way. Water can surround fat molecules and the result is similar. That flowing warm chocolate stops flowing and gets more solid like because the everything is trying to stick together on a molecular level.

And it gets even more complicated. In neither of those cases does it explain why just a small amount of water causes chocolate to get thick, i.e. seize. In effect it the non-water and non-fat (i.e. cocoa solids) parts of the chocolate are absorbing the water. Sort of like a sponge. And the particles swell up. This basically clogs up the system. It’s harder for things to move around. Think of a pile of sand vs a pile of rocks. Which pour easier? The sand, right? Once the water goes in, the ‘sand’ swells up into ‘rocks’ and they don’t pour, or move easily.

This rather leads to why I thought this question was a problem. Because I’ve thought of it as a problem. When I have made drinking chocolate I’ve found it very difficult (impossible) to make an stable liquid one that isn’t too thick or that doesn’t become too thick over time. At somewhere around a 1:1 mixture of chocolate and water it is pretty smooth….but if you wait a little while it thickens up to the point you can’t drink it. If you add more water so it is now 1:2 chocolate to water the same thing happens. It’s smooth and flowing…and then thickens up some time (15-30 minutes?) later. I’ve done this over and over up to something like 1:10 or 1:15. Each time you add water, the cocoa solid sponges start soaking up more water, but it takes time. This is what I thought was being asked about. “Why is my drinking chocolate getting TOO thick?”

So, there. I hope that clarifies a little. The drinking chocolate is getting thick for three reasons. Two types of emulsions (water/oil and oil/water) and what I am calling the sponge effect. Mostly it is the two emulsion, but some is sponge and if you break the emulsions it goes to full blown sponge.  And generally speaking, emulsions tend to be 'velvety' and when they break the mixture gets a bit more clumpy and loses some of it's sheen.

Ask the Alchemist #142

I’ve been making thick drinking chocolate, using the basic milk + chopped chocolate method:

1. heat 1 cup of milk slowly and add chopped chocolate (2.5 oz), whisking thoroughly.

2. once chocolate is incorporated, cool the mixture (at room temp an hour or so, or longer in fridge)

3. when ready to serve: heat, whisking, till the mixture thickens

I am using my own 70% chocolate (only cane sugar and roasted cacao).

My question is, what is happening to make the mixture thicken with the re-heating? It thickens regardless of the type of milk I’m using (even non-fat works). So what is happening with the cacao/butter to cause the thickening? It thickens quite suddenly, when it reaches a certain temperature. It does not thicken with the first heating when initially melting the chocolate. It is quite a lovely texture and flavor, and we won’t make it any other way now. I imagine that the only reason other recipes on the internet include corn starch is to thicken it with the initial heating/melting.

No, no visible oil separation, and no lumps. Before it thickens, I suppose I can sense the very fine grains of my well-melanged chocolate. But that’s barely perceptible, really no different from the texture if I go old-school and make cocoa using gramma’s old-school hershey’s cocoa powder method.

A friend suggested that the milk-fat and the cocoa butter are homogenizing. However, this doesn’t seem accurate to me, since the thickening is exactly the same with non-fat milk.

This kind of problem is difficult to answer without actually seeing your mixture but I suspect it could be a number of things that I’ll just go through. And I will say that I’ve seen this kind of thing myself.

First off I agree it isn’t the milk fat and cocoa butter homogenizing. If anything it would be the opposite. And that may or may not be the case. I agree this isn’t the issue because once something is homogenized, that is it. It means all the oils are wrapped up in water and everything is stable. It’s rather an all or nothing deal. Kind of like pregnancy and death. Once you are one of those, there really isn’t a way to become more pregnant or more dead. And second, the hole goal is to homogenize the chocolate into a liquid. Since that is the goal, it isn’t the problem

Next, I’m going to make a couple observations that may or may not help. When I make hot chocolate from fresh chocolate I make it the other way around. I heat my chocolate and stir in my milk. Just like I do for truffles. I find the emulsion is more stable and does not break as easily. Also, in my experiments I find I use a bit more milk than you are using, and that additional liquid might well be the key. You have a ratio of just over 1:4 chocolate (5:16 technically). My ratio is 1:8 – 1:12. And generally, longer I keep it the more liquid I need which is just what you are seeing.

I see though that it’s thickening for you upon re-heating. That to me points to the culprit being the heating. It may or may not be the temperature itself, but the act. Emulsions are kind of delicate depending on what you do to them. In some cases they are very stable, but in others just break. Generally speaking they are temperature sensitive. They can be stable while hot, but they don’t like agitation. And if you need to stir or shake them, then they need more liquid. So my suspicion is that you are making the perfect storm between heating the mixture and stirring/whisking it too much. I recommend heating in the classic manner of using a double boiler so you don’t have hot spots or a microwave in 15-30 second increments. And stirring VERY gently, not vigorously whisking.

When the emulsion does break (if that is what is happening) I think the reason you are not seeing oil separate is that the chocolate is then immediately seizing and you are seeing it thicken and it is holding the oil in. At that point the chocolate particles start to absorb additional water and the mixture continues to thicken. I’ve seen this a lot in proportions of even 1:10. The only variable is time and the only solution is to continue to add liquid until the chocolate particles are saturated and can start to thin out.

The short of all this is that I can’t give you a 100% effective method for holding hot chocolate. It’s a fresh ‘live ‘ product and best consumed freshly prepared on the spot. Just like many foods like soufflés, rare hamburgers, fresh coffee and innumerable other foods, some things just don’t like to be held and that is just the way it is. And if they are held, it takes a bit of fancy food science and the end result is never quite as good or as special as fresh.