Cocoa: From Bean to Bar

Cocoa beans of varied botanical origins and characteristics are farmed in a variety of tropical locations. Chocolate manufacturers use their learned expertise to formulate blends of various bean types to create unique flavor profiles. While the flavor of milk chocolate is subtle and differences are relatively easy to detect, the impact of bean selection and blending is probably more obvious in dark chocolate. This is due to its higher cocoa-solids content and the lack of interference, or muting, of the profile that the milk and caramelized characters tend to bring about.

Nib alkalization

Alkalization is typically thought of as an important phase in the manufacture of cocoa powders. The process neutralizes or alkalizes the natural cocoa product, and thereby modifies its color and flavor characteristics.

As the pH of the mass is driven upward, the color darkens and the flavor loses its acid character, taking on a deeper, more fudgelike property. Alkalization is critical to the powder manufacture as it extends the color range from the simple yellow-brown of the natural powder to a broad range of red-brown colors. It can be used to create black powder when carried to the extreme.

Alkalization can be completed at several stages of the manufacturing process, including nib treatment, liquor treatment and press cake treatment. Nib and liquor alkalization are used in preparing liquor for chocolate manufacture. Nib alkalization is thought to produce the highest-quality products. Solutions of one or more of several approved alkalizing agents (potassium carbonate being the most common) are mixed with the nibs and absorbed by the bean tissue. The nibs are then dried or roasted to complete the reaction, and are subsequently ground into liquor. Liquor alkalization is accomplished by adding the solutions of alkali to liquor ground from roasted beans or nibs.

Roasting for flavor

The roasting phase of chocolate manufacturing is considered the most critical in terms of the development of desired flavor profiles, as it is at this point where chocolate flavor, as we define it, is created from hundreds of chemical flavor precursors found within the bean.

Roasting systems are either whole-bean roasts (roasting preceding shelling) or nib roasts (shelling preceding roasting). As with other roasting processes, the desired properties are a result of a time-temperature relationship. While there are relatively unlimited parameters available to the cocoa-bean roaster, we tend to think of degrees of roast in three general categories: low, medium and high roasts. The time and temperature parameters within each of these categories are quite variable. Low roasts tend to maintain the volatility of the flavor profile. This produces more-acidic and aromatic liquors, depending on the type of beans roasted and the roasting conditions. Medium roasts, on the other hand, produce less-acid and more-balanced notes.

High-roast conditions are the least acidic and also the least aromatic. Many of the volatile complexes, which make up the complexity of the chocolate profile, are lost under high-roast conditions. The flavor is intense and tends to be more bitter than the medium-roast product. Low-roast liquors are typically preferred by European manufacturers and their consumers, while medium-roast liquors are more common in the United States.

Formulation and mixing

In addition to the types of beans used and the degree to which they are roasted, the basic product recipe will impact the finished dark chocolates flavor. With comparatively lower chocolate-liquor contents, sweet chocolates are less robust and sweeter than their semisweet counterparts. Including milk solids in sweet chocolate can also tend to make for a much-milder profile. The terms semisweet and bittersweet are synonymous terms for products that bear no less than 35% chocolate liquor. In the United States, semisweet chocolate typically averages around 40% chocolate liquor.

Depending on the end application, viscosity could vary considerably, but one would expect sugar contents ranging from around 35% to 55%. Viscosity is controlled by such factors as particle size, or fineness, and the total fat content, which includes fat contributed by the chocolate liquor, added cocoa butter and added milkfat. Milkfat is used to retard bloom in dark chocolatemilk chocolate is known to have superior bloom resistance. Milkfat also depresses chocolates melting point and, consequently, provides a softer bite and texture.

Processing chocolate involves many steps, and there are many variables that can affect its flavor profile.

RefiningThe reduction of particle size that occurs in the refining process has an impact on both the texture (mouthfeel) and flavor release of the chocolate.

ConchingOne of the final stages of the chocolate-manufacturing process, conching subjects the refined chocolate paste to high temperatures and intense mechanical shearing. A number of physical changes occur in the conching cycle. Some of the most-obvious developments to occur while conching, however, are the changes that take place in the flavor profile. Typically, conching dark chocolate strips volatile acids and aromatic complexes. Virtually little-to-no degree of caramelization occurs due to the lack, or low levels, of milk proteins in the recipe.

Aging and storageLike wine and some other foodstuffs, chocolate flavor will change with age. This is particularly true in the case of dark chocolates, where relatively high liquor contents and low levels of milk solids allow for fairly noticeable differences in flavor profiles between freshly manufactured product and one aged 30 to 60 days. Aging has some of the same effect as conchingvolatile acids and aromatics dissipate, leaving a more-balanced profile with fewer sour and pungent notes.

The effect is dramatic at first, but becomes less noticeable with time. Storage of dark chocolate should be done under the same conditions recommended for chocolate products in generalless than 68°F and less than 50% relative humidity. Dark chocolate is less prone to moisture absorption in storage than its milk-chocolate counterpart. Nonetheless, low humidity is highly recommended. Freezing dark chocolate at -20°F will stop the aging process and its associated changes. The products profile will be maintained if one takes care in bringing the product out of freezer conditions and back to ambient temperature. Staging the warming of frozen chocolate avoids forming condensate on the chocolates surface and its subsequent effects on the products rheological properties.

John Urbanski is vice president of technical sales and services, Cargill Cocoa & Chocolate, Lititz, PA. For more information, contact [email protected] .