The themes for Thursday at the Chocolate Technology course were “coatings”, how fats work, and the fun of panning. Everyone is pretty familiar with fat, and it’s pretty important since it’s the basic structural element of chocolate and how it behaves determines how the chocolate behaves. Coatings and panning are slightly more esoteric, though everyone reading this has probably eaten a lot of coating and a lot of panned chocolate. One’s a little scary, and the other is the route to the goodness that is the malted milk ball and its cousins.
Let’s start with the scary part: coatings. There are times when a food manufacturer is making a product where they want some chocolate attributes, but normal chocolate is either not durable enough to survive the handling, or the manufacturing process is going to cause problems with persnickety cocoa butter. Real chocolate, if you take it over 94F, either in cooking or in handling, is going to lose crystallization, and when it cools, is going to break down and bloom. Visually, people will read bloom as “mold” and you are going to have an unsellable product. (Note that even products with “real” chocolate will modify it a little to make it more shelf stable. Looking at the Archer Farms Cherry-Pistachio-Dark Chocolate Granola bars in our pantry, the chocolate is real, but contains butter oil. Why? The butter oil forms a eutectic mixture with the cocoa butter, and prevents the chocolate from forming waxy Type VI crystals.)
So, how does the food industry solve this problem? Coatings! These are chocolate-like products that either supplement or replace cocoa butter with a more stable fat. The result is “engineered chocolate” that doesn’t break down, and doesn’t require tempering for stability and texture. For example, take a look at the ingredients in Kellogg’s Special K Chocolatey Delight. (The term “chocolatey” should be a clue that we’re not dealing with by-the-book chocolate here.) The FDA mandates that to be called “chocolate”, you can only contain the following ingredients: cocoa, cocoa liquor, sugar, cocoa butter, lecithin, vanilla (or vanillin ester), and dried milk. Looking at the ingredients, Kellogg’s is clearly painting outside the lines here. There is sugar, cocoa, lecithin, and milk, but they are hanging out with some strange neighbors: partially hydrogenated palm kernel oil, cocoa processed with alkali, and artificial flavors. No cocoa butter at all!
Kellogg’s has probably found that chocolate chunks floating around in a cereal box tend to have some serious problems (and that cocoa butter is a very expensive ingredient.) This “chocolatey” compound they are using is classified as a coating. The three non-chocolate ingredients are there for very specific reasons. The partially hydrogenated palm kernel oil is an easy to work with (and cheap) substitute for cocoa butter. It can be refined (fractionated) in such a way that it crystallizes with a very high melt point, so the “chocolatey chunk” doesn’t melt or degrade in a hot warehouse or truck, and it requires no tempering. The partial hydrogenation alters some of the fatty acids in the triglycerides that constitute the fat so that it crystallizes and melts in a way that’s closer to cocoa butter. The cocoa processed with alkali is cocoa that has been treated with potassium carbonate to remove acid (due to cheap beans), and to impart a “dutched chocolate” taste. The artificial flavors are there to help compensate for the sensory qualities lost in this engineering. These kind of engineering feats are very common in chocolatey baked goods, and can be hard to detect because the mouthfeel of crunchy cereal or a cookie can mask the texture difference between chocolate and a coating.
We spent the first part of lab today playing with a number of different coatings, seeing how they set up at various temperatures, and tasting them in their naked form. These coatings come in a lot of different grades, depending on their intended application. They range in taste from pretty nasty to pretty good approximations of real chocolate. The fats used to replace cocoa butter range from simple partially hydrogenated soybean and cottonseed oils to very sophisticated oils that have been fractionated, hydrogenated, and interesterified. The lecture after lab was all about what those terms mean….(in simplified terms, which I’m going to surely mangle and oversimplify even further.)
Thalia Hohenthal gave a lecture in the afternoon on basic fat chemistry, and how fats can be manipulated to make better cocoa better replacers or equivalents. Basically (high-school chemistry mode here for a sec) most fat comes as a triglyceride, which is a glycerol backbone that connects to three fatty acids. These fatty acids are carbon chains with acid ends that vary in length (12, 14, and 16 atoms are common), and bond-types (saturated fats have all carbons connecting to two hydrogens, while unsaturated fats have some carbons connected by energy rich double bonds that are less stable.) The type and order of the fatty acids attached to the backbone determines how the fat crystallizes (and determines melting point) and melts (how fast it melts at various temperatures, which determines mouthfeel.) The combination and variety of fatty acid types in chocolate determines how it crystallizes into it’s various forms. Other fats work differently, so engineers mess with them to make them more cocoa-butterish.
The first basic tool is hydrogenation, which eliminates double bonds and adds hydrogen. Generally, this straightens the shape of the fatty acid, which allows for tighter packing, better crystallization, and hence a higher melting point. For example, if you take vegetable oils, which are typically liquid at room temperature, and hydrogenate them, you get Crisco, which is solid at room temperature. Why do this? Liquid oils can’t really hold together structures, but solid ones can. This is why we have tamales, pie crusts, and all the great stuff you can make with butter. However, liquid oils are plentiful and often the byproduct of activities like soap-making. If you are making soap, you can hydrogenate your oil byproducts, get margarine and Crisco, and start “educating” the public about the supposed health threats of butter and lard.
The second tool is fractionation. Oils are very often mixes of fat types, some of which melt at higher temperatures than others. By cooling the oil, you can pour off or otherwise get rid of the liquid oil, and take the higher melting solid oil. This gives you a smaller amount of high meltpoint fat without hydrogenation. Fractionated palm kernel oil (which is different than palm oil) gives a fat with a melt profile that is pretty close to cocoa butter, and is the basis for the most common coating.
The third tool, which must be labelled in European ingredient lists, but not American ones, is interestification. The fatty acid-glycerol bond is an ester bond, and interestification swaps the order that the fatty acids join to the glycerol. So, a fat that might have a kinked oleic fat first on the chain, followed by two straighter saturated fatty acids can be “shuffled” to put the oleic fat in the middle, which yields a molecule that will crystallize much more tightly than the unaltered fat. Interestified coatings are used often in soft baked goods where a plastic, flexible fat is needed to coat without breaking.
This stuff definitely fell into the category of interesting, but not something I think I’ll be applying in any chocolate manufacturing I’m doing. Knowing all this trivia is great for reverse engineering ingredient labels, though! This concludes the mangled high-school science part of the post.
The last part of the day was spend doing panning, which is the process of coating a center like a peanut or malted milk ball with chocolate. Since hand painting chocolate onto individual peanuts with a paintbrush would make for a pretty expensive product, panning was invented. To do this, you use a big, semi-closed bowl (see phto in previous post) with a load of the center. The bowl is rotated continually, and you drizzle untempered chocolate in. The ingredients rotate over each other, and gradually build up a chocolate coating. The trickery comes in preventing the natural consequences of chocolate coated stuff bouncing around in a bowl. You use forced cool air to make the chocolate set up quickly, thus preventing the ingredients from sticking together or to the wall of the bowl. After many slowly drizzled ladles of 110F chocolate, a nice thick coating is achieved. The next steps are to add some starch and corn syrup, which polishes the outside of the candy and provides a protective layer so that you can put another shellac layer on the outside. The shellac armors the candy, and provides a nice shine. Do all this, and you get the world’s tastiest Whopper.
Ed Seguin, one of the lecturers visiting from Guittard, explained why malted milk balls are so fantastic right out of the panner (or up to 24 hours after.) Chocolate at room temperature contains ~20% liquid fat bound up in the solid fat matrix. When you eat chocolate, the solid fat breaks down, and the liquid fat is released quickly, taking chocolate flavor with it. It takes a while to reach the 20% liquid state, though. Fresh chocolate has significantly more liquid fat, and so, when you eat it, releases a boatload more chocolate goodness in that rush of liquid fat onto the tongue. This also makes the chocolate feel “meltier.”