University of Vermont
Department of Plant and Soil Science

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CHOCOLATE: FROM CACAO TO COCOA

Dr. Leonard Perry, Horticulture Professor Emeritus
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 for flavorings from cakes to hot cocoa.  As with many of our foods, chocolate has a direct origin from plants, in this case a tropical tree.  It goes through many processes over many days and in many forms before reaching you as that familiar candy bar or sweet.

Chocolate begins life as seeds in pods clinging to trunks of the cacao (pronounced kah KOW) tree.  The scientific name (Theobroma cacao) comes from the Latin “theobroma” or “food of the gods”, and the Aztec words for bitter and water.  Many I know indeed consider chocolate a food of the gods.

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.  It is a spindly tree, growing 15 to 25 feet tall, with shiny and leathery dark green leaves.  First found growing over 2000 years ago in Central America and parts of Mexico, it now is grown in tropical climates globally.  It was first introduced to Europe by the Spanish in the mid-17th century.
   
Flowers are yellowish-white to pale pink, and are found in clusters directly on tree trunks.  In the wild, they are pollinated by small midge insects, with only about five percent of flowers getting enough pollen to form the cocoa pod fruit.  These fruit are egg-shaped, six inches to one foot long, with thick skins starting green and turning to various colors when ripe—often yellow.  Pods contain from 20 to 50 seeds or “beans”, from which cocoa is made, with about 400 dried beans needed for one pound of chocolate.

Most cacao trees are found on small farm plantations, often in sunny fields where tree life is shorter but yields are higher.  Their cultivation often relies on chemicals, and is less sustainable than culture along the edges of rainforests, or in rainforest corridors.  There are three main varieties of the cocoa plant, Forastero being the most grown variety.

Cocoa 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 cocoa production, with this country the top producer (30 percent of the world’s total production).  World production in 2016 was around $98 billion. Although number 10 in cocoa production, the Dominican Republic leads the world in ethical production, with the lead in both environmental sustainability and fair trade.  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 factor on the assembly-line, the liquid chocolate is squirted rapidly into molds.
   
In addition to its edible uses, chocolate is used medicinally.  Several ailments from diabetes to digestive and chest complaints are treated with unfermented cocoa seeds and their seed coats.  Cocoa butter is used to lower cholesterol, and cocoa powder to treat heart disease.  Many heart specialists and sites (e.g. my.clevelandclinic.org) now recommend a small piece (such as one ounce) of dark chocolate (at least 70 percent, without sugary additives) daily, several times a week.  When I learned this I began my “chocolate therapy” in earnest.
   
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 which originally put together a chocolate exhibit (www.fieldmuseum.org). This exhibit travels across the country each year, such as to the Boston Museum of Science from January 29 to May 7, 2017 (www.mos.org).
 

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