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Conching: Crucial Step in Chocolate’s Flavor and Texture?

by Stephanie Zonis

Traditionally, the manufacture of chocolate includes a stepcalled “conching”, often thought to be important in chocolate’s complex flavor and smooth texture. Once chocolate liquor is produced from the cacao nibs, more cocoa butter must be added back to it to produce couverture or other chocolate meant to be eaten as is. To that mixture is added sugar, milk powder (in the case of milk chocolate) and flavorings, such as vanilla or spices. This mass is heated and undergoes further grinding to reduce particle size, after which conching begins.

Originally, conches were long stone receptacles in which the chocolate mass was pounded, often with stone balls and usually for multiple days (!). The process takes its name from conch shells, which the receptacles resembled in shape. Once mechanization arrived, the chocolate mass was “kneaded” in conches with heavy rollers, which moved back and forth through the chocolate at a regulated speed, making for a far less laborious conching. More modern conches are rotary, with mixing blades that work the mass in a longitudinal motion. Chocolate undergoing conching begins as a doughy or powdery mass, but ends up as a thick fluid. And there are present-day manufacturers who have done away with the conching process altogether, substituting instead an emulsification process that uses a machine resembling an eggbeater.

For how long is chocolate conched? In older equipment, conching periods can range from a few hours up to a few days or longer, and opinions on timing tend to vary widely. Some reports indicate that fine-quality chocolate is conched for up to 96 hours, some insist the conching period is as long as five days, and one article maintained that good chocolate is conched for a minimum of one week. Most chocolate-makers, however, will tell you that chocolate needs to be conched until it’s done. That may seem deliberately vague, but much depends upon what kind of chocolate you’re trying to make, what beans you start with, and many other factors. Mott of Grenada Chocolate states that bulk cocoa beans (often a product of West Africa) need less conching (sometimes, very little conching), because the chocolate liquor produced from them needs to be rid of far fewer strong and “off” flavors. On the other hand, he says, chocolate mass made from fine-flavored cocoa beans usually requires a good deal of conching to bring out the desired taste in the finished chocolate. In any case, modern rotary conches are changing chocolate manufacturing, because they reduce the length of the conching process significantly and can handle enormous quantities of chocolate at one time (in some cases, over 5 tons!), although not all manufacturers will use them. It’s important to remember here that longer conching time doesn’t always mean better chocolate; you have to start the process with good ingredients that have been handled properly, and it is possible to overconch chocolate (one source I’ve seen claims that doing so will result in gummy chocolate; others say the chocolate will just taste flat).

But what does conching accomplish, that it has long been considered so vital a part of chocolate manufacturing? That depends upon your source of information. It is usually said that conching is important to the flavor development of chocolate. Art Pollard, of Amano Chocolate, notes that conching improves the flavor of chocolate by allowing “various volatile flavor components…present in the cocoa bean” to evaporate; these include acetic acid, as well as other acids, by-products of the fermentation of the cocoa bean. Pollard states that many of these components are harsh-tasting; once these are allowed to evaporate, the chocolate flavor can more fully express itself. It’s also been written that the agitation and aeration taking place during conching help to develop the chocolate flavor, perhaps in a manner suggested by Pollard, who believes that the flavor components of chocolate are infused into the cocoa butter and other ingredients during the conching process. Given that chocolate contains at least a few hundred flavor components, not all of which are known or understood well, he may have a point.

Conching may also reduce the size of particles in the chocolate mass (or alternatively, simply smooth the particles out). The importance of this cannot be overstated, as good chocolate should be perfectly smooth on the tongue. In theory, at least, conching accomplishes this via friction. Pollard asserts that the solid particles in the chocolate (including sugar grains and cocoa particles (cocoa particles are made partly out of cellulose, a naturally-occurring plant fiber)) “rub against each other”, causing “the edges on the particle to wear and the particles to become rounder and smoother”, not unlike rocks tumbled repeatedly in a stream. John Nanci, of Chocolate Alchemy, reports that your tongue can no longer determine texture when particles drop below about 50 micron in size, and writes that, ideally, the refining (reduction of particle size) that takes place during conching will reduce the vast majority of particles in the chocolate mass to roughly 18 to 20 micron ( just so we’re all on the same page, 50 micron is a little smaller than 0.002 inches!).

It has also been suggested that conching drives off any excess moisture in the chocolate, which may assist in the evaporation of volatiles. Although the amount of moisture remaining in the chocolate liquor is low (roasting the cocoa beans drives off most of it), conching may help reduce moisture content slightly.

So why the question mark in the title? If everyone knows that conching plays an essential role, what’s the need for speculation? Because not everyone agrees that conching is required for a good-quality product. In the January, 2003 issue of Food Processing Magazine, Managing Editor John Gregerson authored an article in which he questioned what really happens during the conching process. In that article, Gregerson quotes Dr. Gregory Ziegler, an associate professor of food science. Ziegler reported that, in a triangle taste test conducted at Penn State with a panel of twenty members of the confectionery industry, none could tell the difference between conched and unconched milk chocolate. The same thing happened at another taste test held in Munich; industry professionals couldn’t differentiate between conched and unconched chocolates. Over time, Ziegler’s studies have been unable to show a significant reduction in either acid or moisture levels during the conching process. Ziegler believes that chocolate may undergo minute changes during conching, depending upon methodology, temperature, ingredients, and other factors. Other sources have indicated that the addition of the emulsifier soy lecithin to the chocolate mass eliminates much of the need for conching, as that lecithin would coat any sugar/cocoa particles and reduce their rough edges on its own.

So what’s going on here? Have we been hoodwinked by chocolate manufacturers? Is the conching process just a long-term scam of enormous proportions? I don’t think so. My own belief is that conching was originally a necessity for better-quality chocolate. Manufacturing methods were crude, or at least not as sophisticated as they are now. Without conching, a chocolate bar in the late 1800’s or early 1900’s might well have been gritty and harsh in taste. These days, even with far more sophisticated equipment and much-improved knowledge of chocolate chemistry, I believe that what happens in conching might not be entirely understood. It’s possible that any alterations in the physical or chemical composition of chocolate during conching may indeed be subtle. But given chocolate’s sensitivity to its environment in general (chocolate is notorious for being affected by temperature, moisture, proximity to other foods, and more), even small changes may make a big difference in the finished product.

Food manufacturing is no less subject to trends than is any other aspect of life. Unconched chocolate may become all the rage at some point. But until it does, I’ll continue to enjoy my chocolate conched, thankful that a little mystery in its manufacture can help me enjoy it all the more.






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