University of Vermont Extension 
Department of Plant and Soil Science

Anytime News Article


A SWEET PLANT

Dr. Leonard Perry, Extension Professor
University of Vermont


Chocolate has to be one of the all-time favorite foods, especially on holidays such as Valentine’s Day, birthdays, and anniversaries. Of course it is widely used from flavorings for cakes to hot cocoa. As with many of our foods, chocolate has a direct origin from plants.

Chocolate begins life as seeds in pods clinging to trunks of the cacao (pronounced kah KOW) tree (Theobroma). This small tree naturally grows in the understories (under taller trees) in lower elevation rainforests where it requires regular rainfall, steady warm temperatures, constant high humidity, and a rich well-drained soil. First found growing over 2000 years ago in Central and South America, it is now grown in tropical climates globally.

Most cacao is now produced on small farm plantations, often in sunny fields where tree life is shorter but yields higher. This cultivation often relies on chemicals, and is less sustainable than culture along the edges of rainforests, or in rainforest corridors.

Cacao production supports economies in many countries. For example, the lives of about half the 14 million population of the Ivory Coast are estimated tied to cacao production.

The unique pods are produced year round, but are harvested usually twice a year by hand. The large pods then are cut open with a machete, a skilled worker opening 500 pods an hour! The pulpy seeds are scooped out, covered with banana leaves, and allowed to ferment for three to nine days. It is this fermentation that gives seeds their chocolate flavor and rich deep brown color. Seeds are dried on trays or bamboo mats before being shipped to manufacturers.

The process of making chocolate, cocoa powder, and cocoa butter from cacao seeds is complex and may take several days. Seeds first are cleaned, weighed and sorted so they can be blended by each company’s formula. Depending on variety of seed, they are roasted from a half hour to two hours in large rotating roasting ovens at 250 degrees F or higher. This roasting is the key to the best chocolate flavor.

Roasted seeds actually have a husk that must be removed, and this is done by machines with knives that break this outer layer. The seed bits, called “nibs”, then are sorted by size in sieves—a process called “winnowing.” But the process still involves more.

The seed bits, or nibs, are made of about 53% cocoa butter and the rest pure cocoa solids which must be separated. This process begins by “milling”—crushing the seed bits by heavy steel discs and producing a thick paste called “chocolate liquor”. Some of this liquor is then subjected to yet more pressure, this time 25 tons from a hydraulic press. The fatty, yellow substance that is squeezed out is the cocoa butter. It is used in chocolates, cosmetics, and medicines.

Some of the chocolate liquor, however, is not pressed but blended with condensed milk, sugar, and a bit of cocoa butter to form a raw mixture called “crumb”—a coarse, brown powder. The solid part of liquor left after pressing is dried and pulverized into cocoa powder, known for its use in beverages, cooking, and baking.

Yet there’s still more to making that chocolate candy or bar! The raw powder mixture, or crumb, is broken down or “refined” through a series of rollers. Too much and the resulting chocolate becomes a paste, too little and it will be coarse and grainy. In general, Swiss and German chocolate is refined longer than that of England and America, so is smoother. The refined paste next enters vats where heavy rollers knead and blend it, a process called “conching”, which may take six days. Whether this paste is agitated or aerated during conching will affect its final flavor and texture.

The final process before shipping liquid chocolate to manufacturers is “tempering.” This involves warming and cooling the refined chocolate repeatedly, and is used to give chocolate its shiny appearance and to ensure it melts properly. Once at the factory, the assembly-line process is as we might envision, the liquid chocolate rapidly being squirted into molds.

The next time you encounter chocolate, don’t take it for granted. Remember it started in seed pods on cacao trees in the tropics, and went through many processes over many days and in many forms before reaching you. You can learn much more about this wonderful food and its history online at websites such as those of manufacturers, retailers, and the Field Museum of Chicago (www.fieldmuseum.org).

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