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chemicals in cocoa. While there are a number of phytochemicals in cocoa of potentially great interest, there may be others as yet undiscovered or unreported. The main phytochemicals are listed in Tables 8.1, 8.2 and 8.3, together with estimates of concentration where available. A problem with the published information is that starting materials may vary between unfermented beans, fermented beans, beans or cocoa mass after roasting, and, in rare instances, cocoa powder or chocolate. Unfortunately, the materials of greatest interest to health, namely cocoa powder and chocolate, have been subject to the least analysis in respect of phytochemicals.

Table 8.1 Phytochemicals and polyphenolics. Compound

Flavanols Catechins f+)-Gallutaltfüi.n !

t+j-bpigaliocalecnin

Leucocyanidins L1L4

Polymeric leucocyanidins Anthocyanins

After roasting and conching1 (g/100 g)

In milk chocolate2 (mg/100 g)

3-a-L-arabinosidyl cyanidin 3-ß-D-galactosidyl cyanidin

  1. 62.75 0.250.45
  2. 7 2.15.4

0.02

Flavonols Quercetin

Quercetin-3-arabinoside3 Quercetin-3-glucoside3

Total phenolics

Source: Ziegleder and Biehl (16).

2 S. Tarka (personal communication).

13.5

The phytochemicals in cocoa, which are examined below, fall into a number of types. The polyphenolics are quantitatively the largest group (Table 8.1), comprising around 13.5% of the dried unfermented cocoa beans. Most of these are flavanols and flavonols (Fig. 8.1). The former mostly comprise catechins, and of these, by far the greatest single component is ()-epicatechin. The catechins are colourless, while the anthocyanins, present in somewhat lower amounts, give rise to the colour (cocoa purple) in unfermented cocoa beans. As a result of fermentation and drying, much of the anthocyanin is converted to quinonic compounds, giving the beans their characteristic brown colour.

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Table 8.2 Phenolic compounds identified in cocoa and milk chocolate.

Compound

Aesculetin Phloroglucinol

^-Hydroxybenzoic acid Protocatechuic acid

Vanillic acid

Syringic acid Phenylacetic acid o-Hydroxyphenylacetic acid p-Hydroxyphenylacetic acid Phloretic acid p-Coumaric acid

^-Coumaryl quinic acid Caffeic acid

Caffeoyl quinic esters Ferulic acid

Chlorogenic acid Neo-chlorogenic acid Clovamide3 Deoxyclovamide3

1 Ziegleder and Biehl (16).

2 S. Tarka (personal communication).

mg/100 g dry weight1

0.06

0.05

0.32

mg/100 g milk chocolate2

0.05

0.002

0.03

Table 8.3 Phytosterols in cocoa butter.

Phytosterol (g/100 g)

Sterols p-Sitosterol 0.1010.142

Stigmasterol 0.041-0.062

Campesterol 0.0110.022 Di- and triterpenes

Phytol 0.031

Cycloartenol 0.01118.93,4 Aliphatic alcohols

Lignoceryl alcohol 0.0061

Behenyl alcohol 0.0051

Ceryl alcohol 0.0021

3,4 Staphylakis and Gegiou (21, 22).

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Chocolate Aliphatic

Structures of common flavonoid types found in cocoa.

Structures of common flavonoid types found in cocoa.

Quercetin (a flavonol) and two derivatives (a glucoside and an arabinoside) have also been described in cocoa (17) (Table 8.1, Fig. 8.2). The compounds are structurally similar to the simple flavanols.

The leucocyanidins (also termedprocyanidins) are complex polymeric forms

Glycosides Structures

Structure of quercetin and its glycoside derivatives.

Structure of quercetin and its glycoside derivatives.

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