lessons in viscosity
through thick and thin, chocolate is a beautiful marriage of fat and fiber
~~Before we start, a few words on science. I’m not a scientist, though I wanted to be as a child (yes, I was that sixth-grader who dreamed of pathology). My mom majored in chemistry then went into medicine; she indulged my desire to understand how things work. The ventricles in a chicken’s heart, the leg muscles of a frog. None of it grossed me out—my apologies if this assertion, here as we’re about to discuss food, grosses you out. The thing is, we don’t have to be a scientist to gain understanding. We begin to “understand” chemistry every time we temper. We begin to understand aromatic volatiles when we roast, or when we open a new sack of beans.
This is why I believe the most important skill in chocolate isn’t a skill or technique at all: it’s the desire to make sense of something. Data on a page is useful, but only if we know the context, and definitely less so when there is no relatable context. My hope here, in all my chocolate writing and hand-waving, is to help bring a chocolate context into focus. Again: not a scientist. Chocolate maker, endlessly curious about how all this comes together, welcoming a question-driven community, yes. xxoo
Let’s start with a science-y explanation of the composition of cacao:
The physics and chemistry of cocoa beans are very complex and change throughout the life of the bean, mainly depending on the processing it receives and on geographical origin. The main component of cocoa beans is lipid fraction, approximately 50%, mainly constituted by neutral lipids, with a predominant fraction of triglyceride molecules. Protein fraction constitutes 10–15% of the dry weight of cocoa seeds, and it is composed of 52% and 43% of albumin and globulin fractions, respectively. Other proteins, such as glutelins and prolamins, are present in lower concentrations. Cocoa beans contain stimulant substances, such as theobromine, caffeine, and theophylline, named purinic alkaloids, which affect the central nervous system. Various bioactive compounds with vasoactive effects have also been reported in cocoa beans. ~~Info link here
What we need to understand: Lipid fraction = the cocoa fat part, protein fraction (and fiber) = the solids. 50% of a cacao bean is cocoa fat (the butter), and the other roughly 50% is solids.
It’s worth noting that European chocolate was not originally made the way we bean to bar makers do it today. Before chocolate bars there was drinking chocolate (with an unpleasant fat content that floated to the surface and made a smooth product difficult to achieve), which lead to pressed cocoa powder (called cakes) to remove most of the fat, which lead to “eating chocolate.” Eating chocolate was invented in 1847 by taking the powdered remnants, milling with sugar, then adding back in the fat removed from making cocoa powder. Lol, chocolate bars are a by-product.
If we want to talk about chocolate making (hello, yes) and we want to talk about cocoa butter’s role (and yes, we definitely need to), we first need to understand what chocolate is.
Let’s say we want to make a 100% dark chocolate: all cacao, no sugar. We have a bowl of nibs; if we pour the nibs into our bar moulds, do they turn into chocolate? If we pour the nibs onto our work table, will they spread and drip off the side? If we stir a spatula into them, will “chocolate” drip off? nope.
But when we take those nibs and crush them with enough force (the tool/machine we use isn’t what matters here) we’re getting a step closer. By crushing the nibs the cocoa fat they contain is released. How much is released depends on how we crush the nibs, the amount of friction used, and depending on the friction—and if our tool/machine generates its own source—how much heat is applied in the process of the crushing, and the origin we’re crushing.
Probably also what the amount of fat depends on is tied to post-harvest + fermentation, maybe drying approach, age of the cacao, how it was roasted or if it was roasted. But for our purposes here #context we’re focusing on the basics of what chocolate is: crush nibs and fat is released, chocolate is created. Given the global perception of what chocolate is “supposed” to be, we craft makers take this further, by refining to reduce the grittiness, conching to round out flavor and create creaminess, tempering to create shine, snap, and uniformity.
You may think, “I know what chocolate is.”
And you may answer, if asked, that it’s cacao + cocoa butter + sugar. Or, cacao + sugar. Or, just cacao, nothing else.
If you’re a maker delving into milk chocolate, then chocolate includes batches made with cacao + cocoa butter + sugar + milk powder (cow or goat or buffalo, or alt-milk options like soy or coconut or oat or cassava, etc etc etc).
If you make white chocolate, your “I know what chocolate is” answer is cocoa butter + sugar + milk powder (see all the options above).
(And yes: sugar can be cane, maple, coconut, monkfruit, mulberries dried + ground, date sugar, on and on.)
Chocolate is a suspension of solid particles in fat.
When we crush “just nibs” to make a 100% dark bar: cocoa fat released from the cacao melts, the cacao solids (fiber) are reduced down to teensy imperceptible (on our tongue at 15 microns) particles, and these particles float amidst the melted fat.
If we make a two-ingredient 70% dark bar with cane sugar: nibs are crushed, fat is released, solids (cacao fiber + sugar crystals) are refined and reduced, and float in the melted fat.
If it’s a three-ingredient bar, same thing as the other two examples, but with added fat.
Refining cacao + any other ingredients is how we release the inherent fat (what’s inside the nib), reduce particle size of any/all solids so our tongues can’t sense their presence (fiber/proteins in the nibs, sugar if we add it, and milk powder, oat flour, etc etc etc) in order to create this suspension, aka, chocolate.
No matter what type of chocolate we craft, cocoa butter is how we create everything about chocolate that matters. It’s responsible for flow (in the melanger, and in industrial manufacturing, it keeps the flow going through the pipes), unlocking or maintaining aromatic volatiles (fat locks volatiles onto/into the solids), transporting flavor (as the cb melts on our tongue), smooth texture vs sticky (as the particles are refined the cocoa fat surrounds the particles), tempering (it’s the fat that crystalizes and locks in the suspension), shine + snap (cocoa butter crystals), and makes chocolate stable at room temperature: cocoa fat has zero AW (water availability), and doesn’t spoil or go rancid. This is why chocolate bars don’t require the refrigeration that ganache-filled bonbons need in order to stay fresh. Cocoa fat is a solid at “room temperature,” = why, after we make our liquidy, molten, drip-every-where, splatter sky-high batches, once the heat is removed and the batch cools the chocolate solidifies.
Recognize any of these?
“This origin is low in fat.”
“This batch of dark milk is too thin”
“This batch of dark milk is like concrete”
“My tempering failed”
“My batch is very thick.”
“This dark batch is gummy.”
“I added fruit powder but can’t taste it.”
These statements are 100% about the role of cocoa fat. Here are my answers.
“This origin is low in fat.” The maker was unhappy the batch came out very thick and blamed it on the origin. They added more cocoa butter but it still seemed very viscous, sludge-like. Things to consider: how long did you refine? Over-grinding causes the particles to get smaller, which increases the SURFACE AREA for cocoa butter to coat/surround, and leads to gummy/thick chocolate (see below: “This batch is gummy”) If the refining time (and use of tension) was within reason, how clean was the winnow? Husk/shell in any amount (1) adds fiber/solids and (2) does not add flavor and (3) does not add enough fat to balance the fiber it adds.
But, yes, definitely some origins “seem” more viscous, no matter what. And in this case the tell-tale sign is that adding cocoa butter (up to 10%, which is standard in couverture) didn’t make it any less thick. This can be used as a hint of low fat content. But for our small batch pursposes (yes, we could “test” each origin we use by pressing cocoa butter with a small press and comparing), what matters is What does this mean for the chocolate?
It means it’s an origin that might be tricky to deposit in our moulds, will take forever to cool during tempering, not ideal for enrobing (selling as couverture), but! delightful as drinking chocolate: a product that works best without high fat. Also, an origin for use in nut spreads, which will add their own needed fat for spreadability.
More importantly: it goes to why a “one sized 70% to fit all origins” approach isn’t useful. Or even valid! The higher the % the higher the inherent cocoa fat. If the origin seems like it has “less fact,” make a batch at a higher %.
“This batch of dark milk is too thin” The maker did not take into account the three sources of fat when they created the formulation: fat from the cacao nibs + fat from the added cocoa butter + fat from the milk powder. See next issue:
“This batch of dark milk is like concrete” The maker did not take into account the three sources of solids when they created their formulation: fiber from the cacao nibs + solids from the sugar + solids from the milk powder. They thought by just adding milk powder to a dark batch they’d be making a dark milk chocolate. Um, no. Yes, they did make concrete: they needed to increase the amount of cb AND decrease the amount of cacao nibs to make room for the extra solids but have enough cocoa fat for flow.
“My tempering failed” Staring at 20 kgs of melted chocolate it’s easy to think when we temper it’s this whole shebang we’re “tempering.” Yes and no. The cocoa fat is what’s polymorphic and crystalizes. It’s the cocoa fat the tiny particles of cacao and sugar (and anything else we’ve refined into the batch) are suspended in: tempering is what we do to cocoa fat. The other ingredients in this suspended state are (when done correctly) locked into place inside the cocoa fat.
This is why we need cocoa fat in order to temper. That bowl of nibs from the beginning of this post? It can’t be tempered, though the nibs contain cocoa butter. Another example is cocoa powder, which is what’s left of the cacao after the cocoa fat is removed. We can’t temper it either. We can temper cocoa butter (this is cocoa butter seed), and we can temper chocolate. We can’t temper milk powder, cane sugar, oats. Just cocoa butter.
It’s why, when someone asks me Why won’t my olive oil white chocolate temper? and they tell me they used olive oil plus milk powder (or etc) plus sugar, I tell them it won’t temper because (wait for it…) it’s not chocolate. No cocoa fat released = not chocolate.
Fats that inhibit cocoa butter crystalization is another common reason. Rule of thumb: if it has fat (milk powder, soy, seeds, nuts, coconut, etc etc) and it was refined in the melanger (ground down with everything else) it WILL fight against the cocoa butter crystals during tempering. Cocoa butter seed is the miracle child of this issue, because seed = pure/nearly pure type 5 crystals, so when it’s used as a tempering method or helper, it counteracts any disruptive fats. Meaning, it won’t take no for an answer.
This points to another question: “If I stir in nuts as an inclusion will it effect tempering?” no. Only when the fat is released into the batch via refining is this something that needs our attention during tempering.
That said: inclusions that contain fat (chopped nuts, toasted seeds, etc)or were created with fat (say, a brown butter brittle or praline, brownie crumbs from brownie bits made with any type of fat), can cause fat marks on the outside of a bar. If there are little dots or speckles on the outside of an inclusion bar that’s an inclusion issue, not a tempering issue.
What to watch for: if it doesn’t bloom it’s not fat migration; meaning, the temper has broken. A weak temper (few type 5 crystals) of a bar containing fat other than cocoa butter, in an unfriendly tempering environment (high humidity, warm room) can lose temper and bloom (fat migration). Untempered chocolate shows bloom, because the crystals are forming willy-nilly as the batch cools.
Rule of thumb: tempering environment needs to be cool, with air circulating if high humidity is present, and after the bars are moulded if (a) speed-cooled they must be placed in a very cool area to finish setting, or (b) if not speed-cooled must be placed in a cooler area after tempering.
Remember: crystals form at specific temperatures. When we temper we’re trying to create the temperature + time so this can happen. If our room is too warm, how can the chocolate drop to the needed temp? If there’s a lot of humidity (warm air holds more moisture than cold air), picture the moisture droplets blocking the heat escaping from the bars as they cool (cooling = heat transfer), so having air circulation (air conditioning or a fan) is needed. In Oregon, even in winter/cool temps, because we have so much rain I temper with the A/C on.
A fix for fat-containing inclusions: cocoa butter seed + speed-cooling, plus making sure chocolate is stored in a cool setting. The slower the “set” the more likely the fat marks will appear. It’s not “held” in suspension the way a fat that was in the refiner is, so by using seed (consider increasing amount of seed ) and blast-cooling, the tempered chocolate seals in the fat on the inclusion. There’s a lot of science about hard fats vs soft fats, but for our purposes: temper the heck of it.
“My batch is very thick.” Cocoa fat is the source of flow. It’s what makes chocolate liquidy when melted. If a maker tries to minimize cb in an oat milk white batch, they can end up with too little liquid (the cb) and too much solid (oats, sugar). Balancing the fat (liquid) with the solids is key.
“This dark batch is gummy.” Over-grinding causes the particles to get smaller, which increases the surface area for cocoa butter to coat/surround, and leads to gummy/thick chocolate. Adding cocoa butter won’t correct it. But having the particles coated in cb makes them slide past each other, ie, creates a silky texture. This is why conching was invented: a method of coating the particles with cocoa butter without further increasing the surface area. Conching requires reducing the friction, but maintaining motion + heat + time.
“I added fruit powder but can’t taste it.” Cocoa butter has aroma but faint flavor because our tongues sense “fat” and move onto the next thing predominant flavor or taste. Cane sugar = faint aroma, no flavor, but sweet taste. Anything else in the batch? oats, milk powder, etc also have faint-ish flavor. The flavor boost coming from the fruit powder needs to be a high enough amount in relation to the other ingredients to have an intentional impact. Some fruit powders (peach, mango) often require a copious amount. But how does this fit into a cb discussion? Too much fat affects our flavor perception by coating our tongue. This is why tasting chocolate to assess the flavor is best done with a warm mouth, and why (another topic for another day) tasting straight from the melanger when the cocoa butter is melted is not the most accurate way to judge if we’ve reached our flavor goals.
Happy making,
Mackenzie