Cocoa Production, Chemistry, and Use [PDF]

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Cocoa: Production, Chemistry, and Use A Caligiani, A Marseglia, and G Palla, University of Parma, Parma, Italy ã 2016 Elsevier Ltd. All rights reserved.



Cocoa Tree and Beans Cocoa beans represent the seeds of the fruits of cocoa tree (Theobroma cacao L., order Sterculiacae), which is a native species of tropical humid forests on the lower eastern equatorial slopes of the Andes in South America. Cocoa was domesticated and consumed for the first time by the Mayas and Aztecs. The growth of the cocoa tree requires warm-humid climates with temperatures between 20 and 30
C and high and constant humidity, conditions found in areas about 20
latitude north and south of the Equator. Abundant and welldistributed rainfalls are essential because the cocoa tree tolerates a dry season of up to 3 months a year. The cocoa tree is a rather delicate plant that does not tolerate direct strong winds and direct sunlight. In fact, it is generally grown in the shade of other tall trees (banana trees and coconut palms). Trees can reach up to 20 m in height, but are usually kept below 5 m. The fruit is 10–30 cm long and 7–10 cm wide and weighs 400–1000 g. It is an indehiscent drupe called a pod or ‘cabosside.’ It can be spherical, cylindrical, pointed or blunt, smooth, or wrinkled. The pericarp has a thickness of 10–15 mm and can be of different colors depending on the ripeness and variety, turning from green to yellow, from red to orange. The optimum ripeness of the fruit varies according to the variety and generally lasts from 4.5 to 7 months. The fruit is harvested twice a year (in February/March and April/July). The summer harvest usually produces fruit of better quality. The seeds, in the number of 20–60 per fruit, are arranged in regular rows and immersed in a mucilaginous acidic pulp containing glucose and fructose and are called beans. Cocoa beans are the only economically valuable part of cocoa tree because they represent the raw material for the production of cocoa-based products. Each cocoa bean consists of two cotyledons (nibs) and a small embryo, all enclosed in a skin (shell). The cotyledons contain two types of cells: storage or parenchyma cells, containing fat globules, protein and starch granules, and pigmented cells, containing polyphenols and methylxanthines.



and have an optimum taste. Therefore they are considered an excellent quality cocoa. The Criollo is rarely used alone; most frequently it is used to fortify other mixtures having a weak and not persistent aroma. It can be subdivided into Central American Criollo and Venezuelan Criollo. The Forastero cacao (foreigner) corresponds to the subspecies ‘sphaerocarpum’ and resulted from dissemination toward the Amazon Valley in Northern Brazil and the Guyanas. In the nineteenth century, Forastero cocoa seeds were taken from South America to the islands of Sao Tome´ of West Africa, then to Ghana. From Ghana, Forastero spread to other African countries, the most important of which are the Ivory Coast, Cameroon, and Nigeria. In these countries, there was an immediate increase in cultivated area, and they are now the largest producers of cocoa in the world. Forastero represents about 85% of the world’s cocoa production because it is very strong, resistant to disease, and easily cultivated, especially in Africa. The seeds have a strong flavor, not very aromatic and of poor quality, and are generally used in a mixture with other more valuable varieties. Forastero cocoa is now a group very differentiated in several subspecies and hybrids. The best-known Forasteros are the ‘Amelonados’ with pods resembling melon, which were the predominant types traditionally cultivated in West African countries. The Amazonian subgroups show a wide genetic variability. Some Forastero plants growing in particular areas give cocoa of excellent quality (cru) such as Arriba, the national cocoa of Ecuador. Natural hybridization between Criollo and Forastero led to the origin of a third variety of cocoa named ‘Trinitario,’ not found in the wild. It has been reported that the Criollo population from Venezuela and the Amelonado-type Forastero from Guyana could have been involved in hybridization leading to the production of Trinitario. It is difficult to specify the characters of Trinitarios as they may have pod and bean characters ranging from those typical of Criollos to those of Forasteros.



Cocoa Beans Harvesting, Fermentation, and Drying Cocoa Varieties and Geographical Diffusion Two major botanical groups of cocoa are currently recognized: Criollo and Forastero. Criollo (native) corresponds to the subspecies ‘cacao’ and represents the original cocoa, previously consumed by pre-Columbian people. Its diffusion resulted from the dissemination through the Andes toward the lowlands of Venezuela, Colombia, and Ecuador and northward to Central America and Mexico, and to a large number of Caribbean Islands. Today the subspecies Criollo is found in Mexico, Colombia, and Venezuela. It represents only 5% of the world’s production due to its great susceptibility to disease; making it difficult to cultivate. Criollo pods are green to red; the seeds are pale, ferment easily, have a pleasant and penetrating aroma,



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These steps of the process are carried out in the countries of origin. Fresh cocoa seeds undergo fermentation and a drying process to be ready and stable for transport to the countries in which they will be processed to chocolate and related products. Local or regional variations in cocoa plant materials, fermentation procedures, and drying processes lead to a traded good typical of the country of origin; therefore, the composition of the fermented cocoa beans, which is one of the most important factors influencing taste and flavor of the cocoa products, depends not only on the cocoa variety but also on the geographic origin. Cocoa bean fermentation can be considered the first key stage in cocoa products and chocolate production because



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Cocoa: Production, Chemistry, and Use



the series of biochemical reactions occurring in the beans is necessary for inducing the pleasant characteristics of cocoabased products. The fully ripe cocoa pods are carefully cut from the trees, are gathered into heaps, and can be stored for 2–5 days. This enhances prefermentation activity inside the pods. The harvested pods are broken by hitting against a hard surface, and the seeds are extracted from the fruit together with the surrounding sugary mucilaginous pulp (wet beans) and kept for fermentation immediately. The fresh bean is bitter and is not suitable for manufacture of cocoa products because it does not have any flavor, aroma, or taste of cocoa products. All the standard methods of fermentation essentially involve keeping together in heaps, baskets, boxes, or perforated barrels a mass of a reasonable quantity of wet beans for periods ranging from 4 to 6 days and mixing the mass of beans on alternate days. The natural beans’ fermentations are generally carried out according to a traditional process. Among the various methods adopted for fermentation in the different cocoa-producing countries, the heap, tray, and box methods are considered the standard, widely adopted methods. The real substrate of the fermentation is not the bean, but the surrounding pulp that contains about 84.5% water, 10% glucose and fructose, 2.7% pentosan, 0.7% sucrose, 0.6% protein, 0.7% acids, and 0.8% inorganic acids and therefore it is a good substrate where a wide range of microorganisms can develop. Wild yeasts (Kloeckera and Saccharomyces spp.) and bacteria of genera such as Lactobacillus, Bacillus, Pediococcus, Acetobacter, and Gluconobacter, are involved in cocoa fermentation, determining alcoholic, lactic acid, and acetic acid fermentations. The first consequence of fermentation is the loss of most of the pulp around the beans because the pulp substrates are broken down through microbial action; however, more important are the biochemical changes inside the cocoa beans that contribute to a reduction of their bitterness and astringency and improve their color and flavor. In the first stage of the fermentation, yeasts proliferate and convert sugars to alcohol, then the development of lactic acid bacteria occurs, which contributes to sugar breakdown producing lactic acid. After the pulp has run off, the conditions become more aerobic, and the presence of oxygen allows acetic acid bacteria to take over from the yeasts and convert alcohol to acetic acid. Acids that are synthesized from pulp sugars move into the beans and lower the internal pH. The acetic acid diffusing through the beans causes a breakdown of the polyphenol and lipid membranes of the vacuoles of the cell, and the cell contents become mixed, allowing various enzymatic reactions to take place. One of the most important consequences is the oxidation of polyphenols and their conversion to insoluble forms due to the reactions with proteins; these reactions are responsible not only for the removal of the bitter taste from the beans but also for the strong reduction of total polyphenol content, thus affecting the antioxidant and health properties of cocoa. Oxidation of polyphenols is also responsible for the change of bean color, from violet to brown. During and after fermentation, another fundamental biochemical change occurs: internal beans’ autolytic enzymes, in particular carboxypeptidase and aspartic endoprotease, are activated by the low pH; the proteins in the cotyledons undergo hydrolysis, giving rise to amino acids and



oligopeptides, essential precursors for the development of cocoa aroma, arising from the reaction of amino acids with sugars (Maillard reactions) during the subsequent step of roasting. The duration of fermentation ranges from 1.5 to 10 days, depending on the cocoa variety, climate, volume of cocoa mass, and the method adopted. Criollo ferments in a relatively shorter period of 2–3 days, whereas Forastero takes 5–7 days. For the manufacturer of chocolate or cocoa powders the degree of fermentation of the beans is a major quality criterion. Fully fermented cocoa beans have a brown color. It has been shown that too high contents of nonfermented (slaty color) or partly fermented (violet color) beans result in a lack of cocoa flavor in the end product. The slaty beans cause a very acid and astringent flavor profile, whereas the violet beans cause a bitter and harsh flavor. The fermented beans have a moisture content of about 55%, too high to permit the storage of the beans. The moisture content has to be lowered to about 6% for safe storage and transportation. Immediately after fermentation, cocoa beans are sun-dried or dried utilizing hot air. Depending on climatic conditions, the beans are exposed to the sun for about 12–20 days. This method generally gives good-quality beans in traditional areas of cocoa production where the weather is sufficiently sunny, as in West Africa. In the areas where the climate remains unsuitable for drying, artificial drying methods became necessary, utilizing hot air with a maximum temperature of about 60
C. The humidity % after drying is 5–8%, with a weight loss of two-thirds with respect to the fresh bean. The dried beans are packed in jute bags of about 60 kg capacity and traded to transformation countries, where all the following steps (Figure 1) for production of chocolate and cocoa products will take place.



Processing of Fermented Cocoa Beans: Roasting and Production of Cocoa Liquor A key step of chocolate production is roasting. Roasting is performed in the transformation countries, and flavor is formed during this step from the precursors developed during fermentation and drying of cocoa beans. The aroma precursors in cocoa beans, which include free amino acids, low-molecular-weight peptides, and reducing sugars, develop into the cocoa specific aroma through Maillard reactions during roasting. Before roasting, cocoa beans are cleaned to remove stones, metals, and other extraneous materials. Beans are cleaned by passing through a series of screens and magnets. In some cases a preroasting process is applied. The roasting can be performed on whole cocoa beans or on cocoa nibs. In most cases the traditional roasting is performed on whole cocoa beans by hot air treatment, and cocoa shells are removed by aspiration (winnowing). Temperatures of roasting are generally lower that 150
C and for times of from 30 to 120 min. Roasted cocoa beans are then lightly crushed to avoid dust formation, obtaining cocoa nibs. Roasted cocoa nibs are milled to break down the cell walls and expose the cocoa butter. The resulting product is a homogeneous flowing cocoa paste called cocoa liquor containing



Cocoa: Production, Chemistry, and Use



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FERMENTED DRIED BEANS Cleaning Roasting Winnowing



COCOA SHELLS



Grinding COCOA NIBS Milling COCOA LIQUOR



Alkalinization



Mixing



Pressing COCOA CAKE



Sugar, milk etc.



Refining COCOA BUTTER



Mixing



Grinding



Conching



COCOA POWDER



Tempering CHOCOLATE



Figure 1 An overview on cocoa bean processing.



about 55% fats. To produce cocoa liquor with improved dispersibility, the cocoa nibs can be subjected to an alkalinization process (Dutch cocoa process): roasted nibs are treated with a diluted alkali solution at 75–100
C, then neutralized and dried. This treatment causes starch swelling and the formation of porous cell structure of cocoa mass that prevents the formation of sediments in cocoa drinks.



Production of Cocoa Powder and Cocoa Butter Cocoa powder is widely used in the manufacturing of cocoabased products as drinks, cake fillings, ice cream, and so on. To convert cocoa liquor (generally alkalinized cocoa liquor) to cocoa powder, a defatting process is performed by pressing liquor in a mechanical or hydraulic press at 400–500 bar and a temperature of 90–100
C. In this way part of the fat (cocoa butter) is removed, and cocoa cake (compressed cocoa powder) is produced. Cocoa powder is obtained by grinding cocoa cake. Generally the fat content of cocoa powder is 10–24%. Cocoa butter obtained from pressing is separated, filtered, and reused as an ingredient for chocolate and many cocoa-derived products.



Production of Chocolate Chocolate is obtained from nonalkalinized cocoa liquor mixed with sucrose, cocoa butter, emulsifying agents (lecithins), flavoring compounds (vanillin), and eventually other ingredients (milk, hazelnuts, almonds, etc.). Ingredients are mixed to obtain a homogeneous chocolate paste that is then refined to obtain finer particles of < 30–40 mm. The refining step is



performed by single or multiple refining rollers. Further key steps in chocolate production are conching and tempering. Refined chocolate paste is powdery and has a harsh and sour flavor, and conching is necessary to obtain fine chocolate of optimal flavor, smoothness, and texture. Conching is performed in round or oblong rotary conche pots in which the chocolate mass is mixed, ground, and kneaded at temperatures of 65–75
C. Conching times vary from a few hours to many days, depending on the desired final chocolate quality. Generally during conching steps, flavors, emulsifier, and cocoa butter are added. The effect of conching on chocolate paste is a reduction of acidity due to the loss from evaporation of acetic acid and other volatile compounds, loss of moisture, and a more uniform distribution of fats that form a film around each cocoa particle. Tempering is one of the most critical steps to obtain a product with a stable crystalline form of cocoa butter responsible of the good melting properties and the glossy surface of good-quality chocolate. Tempering is performed by cooling under stirring the cocoa mass derived from conching (from 40–50 to 18–28
C). Cocoa is maintained at this low temperature for about 10 min, and then is heated to 32
C. In this way the polymorphic form V of cocoa butter is obtained, with a melting point of 34
C, close to the human body temperature. Different chocolate typologies are produced (Table 1) and can be classified according to the different percentages of cocoa liquor and cocoa butter in the final products or according to the addition of ingredients different from cocoa. Today much of the chocolate consumed is in the form of sweet chocolate, with the addition of sugars (sucrose). Milk chocolate is sweet chocolate that in addition contains milk powder. White chocolate contains cocoa butter, sugar, and milk, but no cocoa liquor.



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Cocoa: Production, Chemistry, and Use



Table 1 (g/100 g)



Examples of formulations for different kind of chocolate



Ingredient Cocoa liquor Added cocoa butter Sugar Whole milk powder



Chocolate Chocolate Milk (50% cocoa) (70% cocoa) chocolate



White chocolate



35 15



70 –



12 22



– 30



50 –



30 –



51 15



50 20



Chemical Composition Lipids Cocoa fat (cocoa butter) represents about 50–58% of the cocoa beans, and its triacylglycerols (97–98% of cocoa butter) mainly consist of palmitic acid (25% of total fatty acids), stearic acid (37%), and oleic acid (34%), with a low amount of linoleic acid (3%). Oleic acid is primarily esterified at the 2-position of glycerol, so the main triacylglycerols are 1,3-dipalmito-2-olein, 1-palmito-3-stearo-2-olein, and 1,3-distearo-2-olein. Cocoa butter is solid at room temperature and melts at temperatures between 30 and 40
C, depending on the polymorphic form. The amount of cocoa butter in chocolate is 21–35%, depending on the addition of cocoa butter to the cocoa liquor.



Protein, Peptides, Amino Acids, and Amines Proteins make up 10–15% of the dry weight of cocoa seeds, the second most abundant constituent after cocoa fat. Proteins are the cocoa fraction that undergoes the most intensive modification during fermentation, where microbiological and enzymatic reactions lead to extensive breakdown of cocoa seed proteins, yielding peptides and amino acids that are the important flavor precursors. Cocoa beans contain four main proteins, albumin, globulin, prolamin, and glutelin. Albumin and globulin are the most important both quantitatively and qualitatively. Globulins are vicilin-like storage proteins consisting of three subunits with molecular masses of 47, 31, and 15 kDa, which are derived from a common 66-kDa precursor. The albumin fraction was identified as a 21-kDa cocoa seed protein having trypsin inhibitory properties. During fermentation, peptide and free amino acids increase and total protein concentration decreases. The globulin protein fraction is the most degraded during fermentation. Cocoa proteins are cleaved to hydrophilic and hydrophobic peptides as well as amino acids through autolysis by two endogenous enzymes, aspartic endoprotease and carboxypeptidase. Fermentation of cocoa beans is fundamental for the activation of these two enzymes by microbial metabolites (such as acetic acid). Changes in the protein composition of cocoa beans have been noted not only during fermentation but also as a consequence of roasting. A decrease in total protein, free amino acids, and albumin are seen during roasting. Regarding amino acids composition, nonfermented beans contain low levels of free amino acids with a 1:1 ratio between hydrophobic/acidic amino acid, whereas in fermented cocoa seeds this ratio significantly increases to 3:1. The increase in the



concentrations of hydrophobic amino acids, such as leucine, alanine, and phenylalanine, is explained by the activity of carboxypeptidase that releases single hydrophobic amino acids and aspartic endoprotease, which hydrolyzes proteins preferentially at the hydrophobic amino acids sites. The free amino acid content recorded in fermented beans ranges from 500 to 1800 mg/100 g, with a prevalence of the hydrophobic amino acids responsible of the formation of Strecker aldehydes and pyrazines, important compounds for cocoa aroma. Among nonprotein amino acids, relevant contents of gammaaminobutyric acids, ranging from 30 to 100 mg/100 g, were detected in fermented cocoa beans, therefore cocoa can be considered an important natural source of this inhibitory neurotransmitter amino acid. Low amounts (20 mg kg1) of biogenic amines deriving from microbial decarboxylation of amino acids occurring during fermentation, as 2-phenylethylamine, tyramine and tryptamine have been found in cocoa. Biogenic amines can be also originated by thermal decarboxylation of amino acids, so their amount is higher in roasted products.



Carbohydrates and Organic Acids The primary carbohydrates in fermented dried cocoa beans are starch (6%) and cellulose (9%). Soluble carbohydrates include glucose, fructose, sucrose (0.08–1.5%), raffinose, and stachyose. Sucrose is partially hydrolyzed during fermentation, providing reducing sugars precursors of aroma development during roasting. Fiber fraction aside from cellulose contains pentoses (1.5%), galactans, and polymers of galacturonic acid. Fibers are concentrated in cocoa shells. Organic acids (1.2–1.6%) are primarily formed during cocoa bean fermentation, and the most represented are acetic acid (0.2–0.7%), citric acid (0.4–0.7%), and oxalic acid (0.3–0.5%). Acetic acid is partly lost during cocoa processing, in particular during conching.



Methylxanthines Cocoa, as coffee and tea, is generally considered a stimulating food, due to the high levels of alkaloids. Theobromine and caffeine in particular are the principal alkaloids found in cocoa. Theobromine (3,7-dimethylxanthine) represents 1.2–2% of cocoa beans, where it is partially bound to tannins in cotyledon cells. During fermentation, the development of acetic acid permits the release of theobromine that migrates from cotyledons to shells. Cocoa shells in fact contain about 1.5% of theobromine, and generally they are reused to extract this alkaloid.



Polyphenols Cocoa is a rich source of polyphenols: the defatted unfermented cocoa beans contain about 120–180 g kg1 of polyphenolic compounds, representing one of the most concentrated natural sources. The polyphenols in cocoa beans are stored in the pigment cells of the cotyledons. Depending on the amount of anthocyanins, pigment cells are white to deep purple. Three groups of polyphenols can be distinguished: catechins or flavan3-ols (37%), anthocyanins ( 4%), and proanthocyanidins ( 58%). The main catechin is ()-epicatechin representing up



Cocoa: Production, Chemistry, and Use



to 35% of polyphenol content. In smaller amounts, (þ)-catechin as well as traces of (þ)-gallocatechin and ()-epigallocatechin have been found. Procyanidins in cocoa consist of oligomers and polymers of catechin and epicatechin. Anthocyanins identified in cocoa include cyanidin-3-galactoside and cyanidin-3arabinoside. Small quantities of quercetin, quercetin glycosides, naringenin, luteolin, apigenin, clovamide, and phenolic acids such as caffeic, ferulic, gallic, and p-coumaric acid have also been found in cocoa products. The high level of polyphenols in raw cocoa beans is progressively reduced during cocoa processing. During fermentation polyphenols diffuse with cell liquids from their storage cells and undergo oxidation to condensed high-molecular mostly insoluble tannins. These reactions are both nonenzymatic and enzymatic catalyzed by polyphenol oxidase. It is reported that epicatechin and catechin content, respectively, are reduced to 10–70% during fermentation. Roasting causes a dramatic reduction of some phenolic substances, in particular clovamide, together with an overall decrease of the antiradical and antioxidant properties of cocoa beans/nibs. High temperatures during the cocoa bean roasting process and also the alkali treatments on the cocoa powder induce the epimerization reaction of epicatechin to catechin, reducing its bioavailability. Moreover, some recent works have achieved chiral separations of catechin and epicatechin enantiomers, showing that the prevalent form of catechin in roasted cocoa products is ()-catechin, a nonnatural in cocoa beans with less bioavailability than (þ)-catechin.



Flavor Compounds Chocolate and cocoa flavors reside in their volatile fraction, which is composed of a complex mixture of up to 500 compounds. The aromatic profile of cocoa beans is very complex and is also dependent on the method and duration of fermentation and drying practices applied. Alcohols, aldehydes, and ketones have been reported as the major groups of compounds found in raw cocoa and at the beginning of the fermentation process (1 or 2 days). Alcohols, esters, and acids (acetic acid mainly) were developed in the middle of fermentation (3–5 days), becoming the most important groups of volatile compounds at the end of fermentation (6–8 days). Alcohols, esters, and pyrazines contents increased during the sun-drying process. Cocoa fermentation is crucial not only to the formation of significant volatile fractions but also for the development of cocoa–chocolate flavor precursors as amino acids and reducing sugars. Via Maillard reactions, cocoa roasting converts flavor precursors formed during fermentation to two main classes of odorant compounds: pyrazines and Strecker aldehydes, and three of these had a strong chocolate flavor: 2-ethylpropanal, 2-methylbutanal, and 3-methylbutanal. Pyrazines were recognized as cocoa/nutty notes: 2,3-dimethylpyrazine, trimethylpyrazine, tetramethylpyrazine, 3(or 2),5-dimethyl-2(or 3)-ethylpyrazine, 3,5(or 6)-diethyl-2-methylpyrazine, and furfurylpyrrole. Conching has an effect on cocoa aroma, although no new key odorant is synthesized during the heating process, and levels of 2-phenyl-5-methyl-2-hexenal, furaneol, and branched pyrazines are significantly increased, whereas most Strecker aldehydes are lost by evaporation.



189



World Production and Human Consumption The cocoa-producing countries are all developing countries and localized in Africa, Central America, South America, Asia, and Oceania. World production of cocoa beans is constantly growing: it has increased from 31 000 tons in 1880 to more than 3 000 000 tons in 2002 and about 5 000 000 tons in 2012. Africa is the continent with the highest production (67%). The largest state producer is the Ivory Coast (about 30% of world production). World cocoa production has risen at an average annual growth rate of 3.3% during the period 2002–12. Between 2002 and 2011/2012, primary cocoa processing growth at an average rate of 2.9% per annum was registered. Europe remained by far the largest cocoa-processing region, followed by the United States. However, with an annual growth rate of 5.6%, the largest regional processing increase occurred in Asia and Oceania. Moreover, in the last 10 years processing in the countries of origin has increased, supported, in some countries, by government policies favoring the export of value-added semifinished products rather than raw cocoa beans. European regions are also the largest cocoa consumers, accounting for 48% of total world consumption of cocoa followed by the Americas, at 33%. Growing consumption has been observed in Asia and Africa. Consumption of chocolate confectionery products increased by 10% between 2002 and 2010 in selected countries, including the major European countries, the United States, Brazil, Japan, and Australia, corresponding to an annual growth rate of 1.2%. World per capita consumption of cocoa has also seen a similar pattern of growth over the review period, rising from 0.54 kg in 2002 to 0.61 kg in 2010. Consumer preferences, especially of European and American consumers, has changed over the last 10 years: chocolate aficionados are asking for single-origin premium chocolate and ‘high cocoa content’ products, with their own distinctive flavors. Cocoa industries are driven to use innovation to appeal to consumers in saturated markets: new flavors, new packaging, and new sizes but also chocolates with health-promoting properties for health-conscious consumers. Sustainable sourcing is also growing in importance for consumers: demand for cocoa grown in a responsible manner is rising, as a consequence of the companies’ response to consumer preferences.



See also: Cocoa: Composition and Health Effects.



Further Reading Afoakwa EO, Paterson A, Fowler M, and Ryan A (2008) Flavor formation and character in cocoa and chocolate: a critical review. Critical Reviews in Food Science and Nutrition 48(9): 840–857. Kratzer U, Frank R, Kalbacher H, Biehl B, Wo¨stemeyer J, and Voigt J (2009) Subunit structure of the vicilin-like globular storage protein of cocoa seeds and the origin of cocoa- and chocolate-specific aroma precursors. Food Chemistry 113: 903–913. Lima LJR, Almeida MH, Rob Nout MJ, and Zwietering MH (2011) Theobroma cacao L., “The food of the Gods”: quality determinants of commercial cocoa beans, with particular reference to the impact of fermentation. Critical Reviews in Food Science and Nutrition 51(8): 731–761.



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Prabhakaran Nair KP (2010) Cocoa (Theobroma cacao L.). In: The agronomy and economy of important tree crops of the developing world, pp. 132–180. Boston, MA: Elsevier. Rohsius C, Matissek R, and Lieberei R (2006) Free amino acid amounts in raw cocoas from different origins. European Food Research and Technology 222: 432–438. Schwan RF and Wheals AE (2004) The microbiology of cocoa fermentation and its role in chocolate quality. Critical Reviews in Food Science and Nutrition 44(4): 205–221. Voigt J, Biehl B, Kamaruddin S, and Wazir S (1993) The major seed proteins of Theobroma cacao L. Food Chemistry 47: 145–151. Voigt J, Biehl B, Heinrichs H, Kamaruddin S, Gaim arsoner G, and Hugi A (1994) In-vitro formation of cocoa-specific aroma precursors: aroma-related peptides



generated from cocoa seed protein by co-operation of an aspartic endoprotease and a carboxypeptidase. Food Chemistry 49: 173–180. Wollgast J and Anklam E (2000) Review on polyphenols in Theobroma cacao: changes in composition during the manufacture of chocolate and methodology for identification and quantification. Food Research International 33: 423–447.



Relevant Websites http://faostat.fao.org/ – Food and Agriculture Organization of the United Nations. http://www.icco.org/ – International Cocoa Organization. http://worldcocoafoundation.org – World Cocoa Foundation.