Ask the Alchemist #103


Almost everything I’ve read both here on the site and in books ranging from hobbyist to professional industry books, roasting and fermentation seem to be a black-box of “flavor development”. There doesn’t appear to be any real hard information either topic. First, for fermentation, traditionally this is just open air fermented with available local bacteria and yeasts and forced to spontaneously ferment until the fermenters think it’s done. As a result of this process, the beans are unsanitary and require roasting/cleaning just to kill off the bad bugs. Is there no research into isolating what strains of what bacteria do what for flavor development? Any research on finding out if a long and slow controlled fermentation may be advantageous for flavor development vs a high temp fast and vigorous fermentation? Think the difference between a Lager and an Ale or going further on the extremes a Lager and a Steam Beer.

With roasting, it seems that almost all of the information is just a trial and error process that you just learn. What are the goals? Is there a specific temp that produces x result. Is just achieving the temperature the goal or is how that temperature is achieved something to think about as well? i.e. is there a difference of throwing a batch of beans in an oven at 500F until the beans reach a desired temp vs starting at 100F and slowly ramping up to the desired temp?

Yep. That about sums it up. But as always, I’ll try to address as many items as I can.

Just because it caught my eye, I wanted to correct one misconception. Fermented cocoa is not made ‘unsanitary’ because it is fermented. It’s made bio-active, but unsanitary connotes unhealthy and/or the presence of pathogens. Much of the ‘unsanitary’ nature is technically contamination, usually from feces. Very generally speaking, native and spontaneous fermentation (sourdough, sauerkraut certain ‘ripe’ cheeses come to mind immediately) naturally produce conditions that inhibit pathogen growth. In most all cases that condition is the production of acids. Cocoa is no different. It’s exactly why you smell vinegar in raw, fermented beans. The microbes produce acetic acid, also known as vinegar. It’s only when the beans are dried out in the open that trouble can occur. Birds, animals, insects, etc. Cross contamination in other words.

Continuing on, fermentations most certainly don’t continue ‘until they think they are done’. That, from our perspective, would give you an over fermented bean, and is WAY past the 3-5 days most fermentations take. It’s totally up to the fermenter (the person) to determine when to stop the fermentation. How they do that is up in the air. Sometimes it’s just ‘3 days’ and is usually just ‘because that’s how I was told to do it’. Hopefully it’s a bit more regimented and it goes until it smells and tastes a certain way. And sometimes, it’s a real art and done until the fermenter, based on a myriad of sensory inputs, says ‘that’s it, they are done’. There is lots of research into what happens during fermentation. Don’t for one moment think there isn’t. But these are complex bio-systems, and teasing that apart into anything meaningful is much harder than you might think. And dangerous if your target or goal isn’t firm. And not dangerous in the safety sense, but in the boring sense. Story time.

I have baked bread for years. Even professionally for a while. And I have to say I am a pretty good baker. But much of the bread I made had a sameness to it. Why? I firmly believe it is we (the American culture) decided to determine the strains of microbes responsible for doing what we saw being done in natural levans (what is often called sourdough now). That lead to isolating a monoculture that allowed us to quickly and reliably make bread rise (instant dried yeast). And my bread did that. It rose. It looked great. It tasted pretty good. But to my tastes it was lacking something. Some spark. Some depth of flavor. A ton of research later I recalled a beautiful book I had across months earlier. Tartine. He (Chad Robertson) talked all about fermentation and that search for the perfect loaf and how he was not finding it with commercial yeasts. My daughter and I started our own culture ala Tartine, and started to learn how to bake bread all over again, and oh the flavors! What had changed? Well, tons of things really, but the largest item was that I was no longer baking with a mono-culture. I was creating with an entire healthy bio-system. I similarly read Cooked by Michael Pollan (thank you Root Chocolate). There are two sections on fermentation (one referencing heavily on Tartine as coincidence would have it), and that same theme of complex transformation is addressed. And now I am working my way through The Art of Fermentation by Sandor Katz (which was also referenced in Cooked, but was on my shelf already before Cooked). And what I consider TRULY amazing (to me) is I didn’t search out any of these books. They all came into my life from three separate, unrelated sources, who all thought they were right for me. And all without having heard these discussions above. Life is just too scary mysterious some days.

What I am coming to firmly believe is that we are not going to ever be able to 100% understand, let alone control these fermentation processes. The absolute best we can do is learn to manage them. And that is only going to come from trial and error and/or tradition. Why do I think this? The most telling case is in Cooked. It describes a raw cheese maker who wanted to understand the complex dance and transformation occurring in the raw, ripened cheese she made. To do that she went off and got a PhD in microbiology. Talk about dedication. And she did indeed learn a myriad of information. She learned how one culture grows until it has exhausted its food supply and dies. The waste products of that first culture set the stage and conditions for another culture to take hold, until it exhausted its food supply and so forth and so on. Such elegance. And at the end of this journey of learning she discovered that the information she had learned didn’t allow her to improve the cheese or control it really any better. It just validated the processes that she already knew!!

Now I’m not against learning and understanding. But I am against taking what you think you have learned of a complex system and simplifying it to ‘repeatable’ and boring. Bud, Kraft, Wonder, and Oscar Meyer are down that path of thinking. Is that what you REALLY want? I didn’t think so.

The crux of the situation is that we simply cannot know everything that goes on in a spontaneous fermentation. There are just too many unknowns. Nearly everything affects the process. To name just a few: variety, age, pollinator, soil conditions, harvest time, moisture, ripeness. And those affect 1000’s of compounds in the cocoa beans. And each in a different way. At the moment, they have identified over 600 compounds related to the smell of chocolate alone. They think they have the top 25 compounds, none of which smell remotely like chocolate alone. When blended together in a particular ratio, our brain says ‘chocolate’. That does not even begin to touch on taste.

This leads right to roasting. What is the goal? To make it taste and smell like chocolate. Really, that’s it.

And for the reasons I stated above, that is all it’s ever going to be. The permutations are just too mind bogglingly huge. Let’s for sake of argument say there are just a mere 10 compounds that affect flavor and can be adjusted by roasting. And to simplify it to a ludicrous, unrealistic degree, let’s just say each compound can either be there or not be there. That gives 3628800 possible taste combinations. If there are 20, that number climbs to 2.4E+10. And I can’t even wrap my head around if different level combinations taste differently or if we had to evaluate 100’s of compounds. The only possible way to say you will get X flavor if you roast this way is to test the specific combination with a particular roast profile (which in itself is so huge to be further mind boggling) and report the flavor….which you and I may not even perceive the same! And sure, there is no way we could tell even 10,000 chocolates apart, but we won’t know what affects that perception unless each is tested. Impossible.

So even if you had a mystical tri-corder and could tell what the compound levels are, there are just too many to test and give results on. And at the end of the day, by the time you compile all that data, you have to make it accessible and to do that you have to generalize which leads us right back where we started. Roast 12-20 minutes with a final temperature 250-310 F. Longer and lower for more delicate beans, shorter and hotter for more sturdy beans. Roast a longer to reduce acidity. Roast shorter to increase acidity. And ALWAYS remember those are generalities. I roasted a batch last week. 55 minutes to 265 F. The most pleasant roast, aroma wise, I have EVER done. And the chocolate was ok. Not great. Not bad. Maybe it needed 270 or 275 or 110 minutes to be great. I just don’t know. But I do know I preferred the same bean roasted to 265 F in 20 minutes. But I have no idea why.

So as much as you want exact answers, they just are not there to give nor can they ever be. The numbers and permutations are just complex. Life is just too complex. It’s that simple. So you are left with trial and error, using your senses to the best of your ability, building your own personal database of experience and going from there. I really and truly wish I could give you more, but I can’t.

Luckily, nature has a way of taking care of itself. Cocoa beans left in a pile will ferment. Fermentations that have gone too far smell of rot (since that is what they are doing, being digested by microbes), so we stop it before it rots. When we roast, the smell should always be nice. Acrid is bad. Burning is bad. It’s innate to us not to like those flavors and aromas. Keep out of the bad zone and what you make will most likely be good. Maybe not great. Maybe not what you were shooting for. But not bad. Trust in that. Accept that I am only going to offer you beans that have been fermented well. Roast so it smells nice at basically all times. And enjoy the experience and the chocolate that you made with your own hands. To borrow from Michael Pollan, enjoy the hand flavor of what you have made. At the end of the day, that is what means the most to me.

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