Tannins cocoa

Although flavor precursors in the unroasted cocoa bean have no significant chocolate flavor themselves, they react to form highly flavored compounds. These flavor precursors include various chemical compounds such as proteins, amino acids, reducing sugars, tannins, organic acids, and many unidentified compounds. 

The natural moisture of the cocoa bean combined with the heat of roasting cause many chemical reactions other than flavor changes. Some of these reactions remove unpleasant volatile acids and astringent compounds, partially break down sugars, modify tannins and other nonvolatile compounds with a reduction in bitterness, and convert proteins to amino acids that react with sugars to form flavor compounds, particularly pyrazines (4). To date, over 300 different compounds, many of them formed during roasting, have been identified in the chocolate flavor (5). 

The cacao plant, Theobroma cacao, is the source of chocolate which is well known and highly prized in international commerce. The cacao pods contain beans which are fermented and pressed to provide a brown liquid which is the raw material for chocolate. The press cake is ground and sold as cocoa and it also provides a brown colorant. The pods, beans, shells, husks and stems have also been suggested as colorants. They contain a very complex mixture of acyl acids, leucoanthocyanins, flavonoid polymers, tannins, and catechin-type polymers.33... 

Cocoa seeds contain 35-50% of oil (cocoa butter or theobroma oil), 1-4% theobromine and 0.2-0.5% caffeine, plus tannins and volatile oils. During fermentation and roasting, most of the theobromine from the kernel passes into the husk, which thus provides a convenient source of the alkaloid. Theobroma oil or cocoa butter is obtained by hot expression from the ground seeds as a whitish solid with a mild chocolate taste. It is a valuable formulation aid in pharmacy where it is used as a suppository base. It contains glycerides of oleic (35%), stearic (35%), palmitic (26%), and linoleic (3%) acids (see page 44). 

Hallas, C. A., The Anthocyanin and Tannin Content of Cocoa, BFMIRA Research Rept. 13... 

Loew says, the process of fermentation depends especially on yeast cells which increase rapidly in the syrup of the cocoa bean, with the formation of alcohol and C02. Also bacteria take part in the fermentation, oxidizing the alcohol to AcOH. A rise in temperature takes place and the slimy tissue surrounding the seeds comes off and collects on the bottom of the vat. The removal of this tissue is the chief end of the fermentation. It causes the seeds to be more easily dried. An oxidation of the tannin takes place which causes the brown color of the bean. The taste and the aroma depend on the fermentation as well as on the roasting. ... 

The major analytes of coffee include caffeine, chlorogenic acids, and flavor and volatile aromatic components. The major analytes in cocoa are me-thylxanthines, mainly theobromine and trace amounts of caffeine, cocoa fat, and lipids. Other analytes of interest in cocoa are tannins, pigments, and aroma components. The major analytes of tea are the methylxanthine alkaloids, including caffeine and theophylline, polyphenols (catechins, tannins, and related flavanols), and volatile and aromatic components. Analysis of black tea would also include theaflavins and thearubigens, which are oxidation and condensation products of polyphenols. 

Hermann found in coffee a resin (Harzstoff) and a soapy principle (Seifen-stoff). Chenevix found a bitter principle in coffee but did not isolate it. Cadet, who mentions Chenevix and Paysse, found what he thought was gallic acid and a peculiar acid, which Paysse had called acide cafeique. Thomson, who mentions Hermann and Cadet, says Paysse tried to show that Chenevix s bitter principle is a peculiar acid, cofEc acid which, says Thomson, reddens vegetable blues, but in other respects does not seem better entitled to the name of acid than tannin. Caffeine was perhaps first satisfactorily established and named by F. F. Runge in 1821, and independently by Pelletier and Caventou and Robiquet. The bitter principle (thein) of tea was isolated by Oudry (no initials are given). Berzelius s suggestion that theine and caffeine are identical was confirmed by Mulder and by Jobst. Theobromine was discovered in cocoa by Woskressensky. ... 

Tannins (proanlhocyanidins) Cranberries, cranberry products, cocoa, chocolate Improve urinary tract health. Reduce risk of cardiovascular disease... 

De Brito ES, Garcia NHP, Amancio AC (2002) Effect of polyphenol oxidase (PPG) and treatments on total phenol and tannin content of cocoa nibs. Ciencia e Tecnol de Aliment, Camp 22 45 ... 

Flavanol monomers and proanthocyanidins (syn. condensed tannins) are polyphe-nolic compounds derived from plant secondary metabolism being present in a wide variety of plants and plant-derived foods such as fruits, cereals, seeds, wines, ciders, teas, beers, and cocoa [1-7]. 

Theobromine (3,7-dimethylxanthine), which is 1.2% in cocoa, provides a stimulating effect, which is less than that of caffeine in coffee. Therefore, it is of physiological importance. Caffeine is also present, but in much lower amounts (average 0.2%). A cup of cocoa contains 0.1 g of theobromine and 0.01 g of caffeine. Theobromine crystallizes in the form of small rhombic prisms which sublime at 290 °C without decomposition. In cocoa beans theobromine is often weakly bound to tannins and is released by the acetic acid formed during fermentation of the beans. Part of this theobromine then diffuses into the shell. 

In addition to alkaloids (mainly theobromine), tannins, and other constituents, cocoa husk contains a pigment that is a polyflavone glucoside with a molecular weight of over 1500. This pigment is claimed to be heat and light resistant, highly stable at pH 3-11, and useful as a food colorant it was isolated at a 7.9% yield.2°... 

Guarana has stimulant and astringent properties due to its caffeine and tannins contents (also see coffee and cocoa). 

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